When Hubble stared at nothing for 100 hours (2015)(nationalgeographic.com)
nationalgeographic.com
When Hubble stared at nothing for 100 hours (2015)
https://www.nationalgeographic.com/science/phenomena/2015/04/24/when-hubble-stared-at-nothing-for-100-hours/
230 comments
Thank you. It's incredibly obnoxious when a website says I have 3 free articles left to read this month and 10s later pops up a non-dismissable pop-up that forces registration.
> “With this achievement, the estimated number of galaxies in the universe had multiplied enormously — to 50 billion, five times more than previously expected,”
This numbers is sheer incredible. Each of them contains 50 billion stars. How come some think we’re alone in this universe?
EDIT: yeah, I know speed of light and all... it’s just a stupid fantasy that is fueled by these numbers
This numbers is sheer incredible. Each of them contains 50 billion stars. How come some think we’re alone in this universe?
EDIT: yeah, I know speed of light and all... it’s just a stupid fantasy that is fueled by these numbers
For some reason, something that's always stuck with me is my grandfather asking the priest at my school (it was a church school) "Do you think aliens exist?" and him replying "I'd be naïve to think they don't".
The sheer number of stars seems to make it likely we aren't alone. Whether we're practically alone, and will remain forever separated from our nearest intelligent neighbours, is a more interesting question IMO (though somehow discovering we are completely alone would be fascinating in its own right and raise further questions).
The sheer number of stars seems to make it likely we aren't alone. Whether we're practically alone, and will remain forever separated from our nearest intelligent neighbours, is a more interesting question IMO (though somehow discovering we are completely alone would be fascinating in its own right and raise further questions).
I just had this thought that, say, in prison, or a bad relationship, there could be a person in the room right next to yours, and there could be such a gulf between you that you are in fact completely and utterly alone.
... If there's no communication between you, what else would you call that but "alone"?
Edit: I should say that I think I hear what you're saying, and I further think that there's always hope that you could bridge that gap.
... If there's no communication between you, what else would you call that but "alone"?
Edit: I should say that I think I hear what you're saying, and I further think that there's always hope that you could bridge that gap.
Well they are so far away we are for all practical reasons, alone. Suns will be born, die, reform from the ashes many times before a message at the speed of light could make a round trip. And that is to the ones at only a few billion light years away.
Some galaxies have stars in the trillions. Even the Milky way is at something like quarter of a trillion. It's mind-boggling.
I have this nagging thought that maybe intelligent life really is a coincidence of a grand cosmic scale. Maybe we really really are all alone in this galaxy and among many others. What an incredible opportunity we are given, and how we squander it with our bickering.
Lol, would love to know the thought process of someone that bothered to downvote you.
if you don’t believe aliens exist, you are wronggggg!!!
if you don’t believe aliens exist, you are wronggggg!!!
Yeah, that one surprised me too.
I was looking at the Hubble eXtreme Deep Field photo and in there locked on a galaxy that was just a dot and imagined that out of the billions of stars and trillions of planets in that dot, there could be life on a planet with a variety and richness and vast history that is unfathomable to us. Us and them, two dots unbelievably far away yet parallelly flowing through time. I think the only reason Space doesn't generate a lot more interest than it draws now is because it is truly mind boggling.
Will you reach a limit if you come up with a telescope ten times as big - where is the real limit? Is that an exciting question? I think there is a bit of rhetorics involved at interpeting the result of this experiment.
You can pretty much make a telescope as large as you'd like, depending on your technological level. Hypothetically, you can use gravitational lensing to make a telescope via the sun! It's rather unfeasible at our current level of rocketry, but in time, maybe! Article: https://blogs.scientificamerican.com/observations/using-the-...
You can also use Earth's atmosphere as a lens too! It's an amazing video: https://www.youtube.com/watch?v=jgOTZe07eHA
Going even crazier, I can imagine we could some day use a massive black hole as a giant telescope.
You can also use Earth's atmosphere as a lens too! It's an amazing video: https://www.youtube.com/watch?v=jgOTZe07eHA
Going even crazier, I can imagine we could some day use a massive black hole as a giant telescope.
Such a brave soul.
This and the later XDF (eXtreme Deep Field) surveys still raise the hairs on the back of my neck every time I look at them. It really puts our human scale and importance in perspective.
> It really puts our human scale and importance in perspective.
Speaking of scale a new large structure was discovered a supercluster which has been named "South Pole Wall" it;s 1.5 billion light years in length.
https://www.youtube.com/watch?v=lnUUKJMAmFo
Speaking of scale a new large structure was discovered a supercluster which has been named "South Pole Wall" it;s 1.5 billion light years in length.
https://www.youtube.com/watch?v=lnUUKJMAmFo
https://en.wikipedia.org/wiki/South_Pole_Wall for anyone else who prefers reading to watching videos.
Anton the channel owner puts links to papers relating to what he is discussing.
The paper he linked to is not very long: https://iopscience.iop.org/article/10.3847/1538-4357/ab9952
The paper he linked to is not very long: https://iopscience.iop.org/article/10.3847/1538-4357/ab9952
If you haven't yet, you should read Vonnegut's short story "The Euphio Question", which was written well in advance of deep field, but is eerily complementary.
Just imagining the interstellar space does it for me. Our planet is a marble in a cathedral compared to the solar system, and between stars not even a speck of sand.
It's hard to imagine that the tiniest pixel spec of a galaxy hold hundreds of millions or more of stars like our own which might have planets with people on them. Of course they might also be 12B years gone.
This almost makes me dizzy: https://en.wikipedia.org/wiki/Hubble_Ultra-Deep_Field#/media... (it's a picture of the night sky showing what exactly Hubble was imaging with the Moon for scale)
I never really understood how XDF is only that tiny patch of the sky and yet it has a godzillion of galaxies inside it!
I never really understood how XDF is only that tiny patch of the sky and yet it has a godzillion of galaxies inside it!
The full resolution versions of the public domain images from the article are on that page: https://en.wikipedia.org/wiki/Hubble_Ultra-Deep_Field
Unlike the lower resolution versions National Graphic scoldingly claims are under copyright when you right click to try and view the full image.
Unlike the lower resolution versions National Graphic scoldingly claims are under copyright when you right click to try and view the full image.
TIL: Moon covers 0.5°.
The Sun- also 0.5°
Wow, they're both the same size! What a cool coincidence! Just think what would happen if the moon passed exactly in front of the sun! Has it ever happened? Has anybody looked up at the sky when this happened? I wonder what it looks like.
Yeah full solar eclipses are a lot of fun. I had an experience in Seattle a couple of years ago.
They perfectly align and all you see is a thin ring from the sun flares.
In that perfect eclipse, you can look at the sun with the naked eye and it’s beautiful and humbling. Like the day suddenly turns into a night for a few minutes.
The TV series “Heroes” was all about this eclipse. It’s a fun show if you enjoy this kind of things.
They perfectly align and all you see is a thin ring from the sun flares.
In that perfect eclipse, you can look at the sun with the naked eye and it’s beautiful and humbling. Like the day suddenly turns into a night for a few minutes.
The TV series “Heroes” was all about this eclipse. It’s a fun show if you enjoy this kind of things.
I witnessed the 2017 total solar eclipse in person. Very eery feeling. It's worth noting that you should still not look at the sun during a total eclipse as the corona is still bright enough to do damage, and your pupils are dilated.
> look at the sun with the naked eye
Not recommended.
Not recommended.
Only for the lucky 50million-ish year window we are currently in
https://astronomy.com/magazine/ask-astro/2000/10/why-is-the-...
https://astronomy.com/magazine/ask-astro/2000/10/why-is-the-...
I don't know of anything more awesome (in the literal sense of the word) than these photos. It makes my wonder just how densely packed (ignoring variation in distance) the area is. What will we see when we start looking between those dark spots? What if there's literally something in every direction...
Before our modern understanding of cosmology, a serious question astromers asked is "why is the night sky dark". If there truly were stars/galaxies in every direction you would expect the entire night sky to be bright, as no matter which way you looked you would see a star; and the combined light of all of those stars should illuminate the sky.
As it turns out, empty space isn't dark, but rather illuminated by the cosmic microwave background. This suggests that the space between us and this boundary in space from when photons started to be able to move mostly freely is mostly empty. Otherwise this backround would either be over-shadowed by stars, or obscured by whatever stuff was obscuring said stars.
Of course, it is important to keep in mind the speed of light implications.
As it turns out, empty space isn't dark, but rather illuminated by the cosmic microwave background. This suggests that the space between us and this boundary in space from when photons started to be able to move mostly freely is mostly empty. Otherwise this backround would either be over-shadowed by stars, or obscured by whatever stuff was obscuring said stars.
Of course, it is important to keep in mind the speed of light implications.
For more on this, see Olbers’ paradox - https://en.wikipedia.org/wiki/Olbers%27_paradox
But, Hubble demonstrates that every line of sight is actually ends on surface of a star or an object, so what is your point?
When did Hubble demonstrate that? What the experiment in the article showed is that seemingly empty regions contained stars. If you want to claim that every 1 dimensional line of sight ends on an object, then you need to explain how the cosmic microwave background manages to reach us. Unless, of course, you count quark-gluon plasma as an object; in which case we do pretty much hit a wall in every direction.
It looks like your naked sight is much better than Hubble telescope. Congratulations!
You should read a basic Astronomy book and dont make a fool of yourself here
You mean, I should _write_ a book, right?
See also Olber's Paradox:
https://en.wikipedia.org/wiki/Olbers%27_paradox
https://en.wikipedia.org/wiki/Olbers%27_paradox
For me, those images are a sliver of the Total Perspective Vortex. The more I try to comprehend them the more blown away I am by them.
> In 1995, astronomer Bob Williams wanted to point the Hubble Space Telescope at a patch of sky filled with absolutely nothing remarkable. For 100 hours.
It was a terrible idea, his colleagues told him, and a waste of valuable telescope time. People would kill for that amount of time with the sharpest tool in the shed
And by 'Bob Williams', we mean the director of the Space Telescope Science Institute, which operates Hubble. Williams chose to use some of the predefined Director's Discretionary Time to explore the limits of the telescope and our understanding of the universe.
https://en.wikipedia.org/wiki/Robert_Williams_(astronomer)
It was a terrible idea, his colleagues told him, and a waste of valuable telescope time. People would kill for that amount of time with the sharpest tool in the shed
And by 'Bob Williams', we mean the director of the Space Telescope Science Institute, which operates Hubble. Williams chose to use some of the predefined Director's Discretionary Time to explore the limits of the telescope and our understanding of the universe.
https://en.wikipedia.org/wiki/Robert_Williams_(astronomer)
I adore these images, and deeply respect the reputation risk in getting them.
I also believe that even if we found nothing at all, it would still advance our understanding of the universe as we could confidently say what limits there might be.
I also believe that even if we found nothing at all, it would still advance our understanding of the universe as we could confidently say what limits there might be.
Unfortunately people would not have gotten nearly as excited when seeing nothing, and the nay-sayers would have made this very clear.
These things are always as much science as they are politics, so the reputation damage would have been real.
These things are always as much science as they are politics, so the reputation damage would have been real.
If nothing had been seen, the implications would have been spectacular.
Experiments worth doing are worth doing no matter the result.
Experiments worth doing are worth doing no matter the result.
Right, I suspect that there was much more behind Bob's deep field study than TFA presents.
More importantly, could he have done the same thing in today’s world and political realities that he did then?
While I agree with you about PR and reputation (sadly), it would be valuable for scientists as a Null value. I would put it on the same level as the Aether experiments.
Yes the point I tried to make was explicitly about the political aspects. I agree that from a scientific point of view, the null value is almost as valuable as what we got now.
I think it's not so much that it was a huge gamble. It was more that it was a sensitive time politically, to make that gamble.
I mean, if they found nothing? Sure, that's still a question Hubble should be trying to answer. But right after such a rocky start, the politically obvious choice would have been to go for easy wins.
The timing was as ballsy as anything else, if not more so.
I mean, if they found nothing? Sure, that's still a question Hubble should be trying to answer. But right after such a rocky start, the politically obvious choice would have been to go for easy wins.
The timing was as ballsy as anything else, if not more so.
From the article:
> And, to be honest, it didn’t really matter how much his colleagues protested. As director of the Space Telescope Science Institute, he had a certain amount of Hubble’s time at his personal disposal. “The telescope allocation committee would never have approved such a long, risky project,” he explains. “But as director, I had 10 percent of the telescope time, and I could do what I wanted.”
Also:
> “Scientific discovery requires risk,” Williams says. “And I was at a point in my career where I said, “If it’s that bad, I’ll resign. I‘ll fall on my sword.’”
> And, to be honest, it didn’t really matter how much his colleagues protested. As director of the Space Telescope Science Institute, he had a certain amount of Hubble’s time at his personal disposal. “The telescope allocation committee would never have approved such a long, risky project,” he explains. “But as director, I had 10 percent of the telescope time, and I could do what I wanted.”
Also:
> “Scientific discovery requires risk,” Williams says. “And I was at a point in my career where I said, “If it’s that bad, I’ll resign. I‘ll fall on my sword.’”
Well, my opinion (now) is that it wasn't so huge a gamble and completely unknown. The galaxy luminosity function (# galaxies per brightness, basically for those unfamiliar) is a curve they knew the beginnings of through images to date, and it wasn't unreasonable to suppose it would keep going beyond what had been done.
It's not like you would expect galaxies to suddenly stop being found if you took exposures a little deeper. It was a good (and not outrageous) bet. I would liken it to -- if we built a better microscope and looked deeper into a cell, is it likely we'd find nothing new? Probably not.
It's not like you would expect galaxies to suddenly stop being found if you took exposures a little deeper. It was a good (and not outrageous) bet. I would liken it to -- if we built a better microscope and looked deeper into a cell, is it likely we'd find nothing new? Probably not.
I'm glad you prefaced this with "(now)" ie: hindsight. There's always a considerable chance that tests of the untested / unproven will remain inconclusive, even if there's some evidence we should find something.
It's extremely risky to allocate a huge amount of finite resources to these unknowns, when there are so many areas we KNOW we can help advance with those finite resources. The fact that he was ready to retire, if the picture came back with barely anything in it, gives a sense of how bad that waste of resources would have been.
Future us might not think it is such a gamble to send a probe to look for life in the oceans of Saturn's moon Enceladus. There's evidence of abiogenesis from deep sea vents on Earth, and Enceladus has very similar conditions. But present us knows there are so many unknowns and possibilities of failure even if something is there. And there are so many other useful ways to use the finite resources of our space program.
It took a lot of courage on Bob Williams' part to explore this.
It's extremely risky to allocate a huge amount of finite resources to these unknowns, when there are so many areas we KNOW we can help advance with those finite resources. The fact that he was ready to retire, if the picture came back with barely anything in it, gives a sense of how bad that waste of resources would have been.
Future us might not think it is such a gamble to send a probe to look for life in the oceans of Saturn's moon Enceladus. There's evidence of abiogenesis from deep sea vents on Earth, and Enceladus has very similar conditions. But present us knows there are so many unknowns and possibilities of failure even if something is there. And there are so many other useful ways to use the finite resources of our space program.
It took a lot of courage on Bob Williams' part to explore this.
Except the models they had at the time indicated there should be a lot fewer galaxies than they actually found. Five times fewer. I that’s what the deep field had shown, it would merely have confirmed what people already thought they knew anyway. The reason the actual deep field is so interesting is because it dramatically expanded the scale of the observable universe. If it hadn’t done that, we wouldn’t be talking about it.
10% is a remarkable amount of time. I was astonished when I read that number. I would have expected it to be around 1% at max.
Discretionary time is usually given to projects which otherwise didn't get any time, it's not usually hoarded for the director himself.
I hadn't heard of this concept before, but I find it appealing. It's kind of like an insurance policy against groupthink, or a diversified long bet. More projects should have a small percentage of time dedicated to a drastically different allocation process, with iron-clad protection (like "director's discretion") to prevent manipulation, to help prevent getting stuck.
I find that asymmetric/concentrated power in the appropriate (!) hands can lead to better results for most things. For instance, I'd rather put my money in a company where the CEO has the proper vision and considerable agency over one that is ruled by committee, like most tech titants. I wouldn't advocate for a regression to authoritary regimes, but I think they can stabilize and accelerate progression towards greater objectives as opposed to a segmented and elected political power which rules on a 4 (maybe 8) years "vision" (colored heavily by polls optimization), for example China or ex-Yugoslavia. Linux probably benefited greatly from having Linus. It can obviously go wrong (North Korea, too many kings to count, WeWork, Theranos..).
I think it's a good hedge for NASA to have this policy, they probably selected a good pick in the first place, and if it went wrong they could probably easily replace the position [source needed].
I think it's a good hedge for NASA to have this policy, they probably selected a good pick in the first place, and if it went wrong they could probably easily replace the position [source needed].
Singapore is a fairly good example of a (mostly) benign dictator - built a modern developed city-state out of what was basically a swamp.
Good example is Google vs Amazon/Apple. Google's culture is very much a democracy of sort inside. Apple/Amazon more top down direction.
The problem, of course, is survivorship bias.
Its similar to Monarchy vs Democracy. A great monarch can get a lot more done than a leader in a democracy. They can also do a lot more harm.
If you want to maximize the potential of a company, you must choose a great CEO and give them near-unlimited power. The problem is that most boards aren't qualified/able to find one, which is why founders that survive the filter to growing into a mega-company are the ones you listed- they are the ones who've already got one.
Tim Cook is doing fine, but he doesn't wield near the influence Jobs did- look how long it took him to finesse Joni Ive out of the company, despite his choices causing massive problems for Apple.
Its similar to Monarchy vs Democracy. A great monarch can get a lot more done than a leader in a democracy. They can also do a lot more harm.
If you want to maximize the potential of a company, you must choose a great CEO and give them near-unlimited power. The problem is that most boards aren't qualified/able to find one, which is why founders that survive the filter to growing into a mega-company are the ones you listed- they are the ones who've already got one.
Tim Cook is doing fine, but he doesn't wield near the influence Jobs did- look how long it took him to finesse Joni Ive out of the company, despite his choices causing massive problems for Apple.
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At tech companies, it’s often in the form of hackathons, hackweeks, or 20% time.
Is 20% a real thing anywhere, aside from select google employees?
Googler here. Yes, in my team we have a colleague that is spending one day a week trying to solve a particular problem we have with a completely novel approach. He had an idea after we presented what we are up to in one of our Org summit. Furthermore, it is really a streamlined process, ie you only need your manager approval.
That's not 20% time. That's a project for your primary work area.
When I was at Google (long ago), you were very welcome to do a 20% project. But it was not considered in your performance review.
So you'd better do it outside of your regular job, adding up to a 120% workload.
So you'd better do it outside of your regular job, adding up to a 120% workload.
It is at 3M
The Hubble schedule is planned out roughly a year in advance. If any unexpected astronomical events occur, they use discretionary time to study it.
Wow! The culture sounds very risk averse. I mean 100 hours is not much given how long the telescope remained opertional
HST is in a 96-minute orbit, up to half of which is blocked by the Earth, depending on where in the sky you point it. Getting time on it is an extremely competitive process - the recent cycle had over a thousand proposals, requesting over 24,000 orbits worth of observing time, and they had only 2700 orbits to allocate [1].
This sort of proposal pressure (over 9:1 oversubscription) leads to very conservative proposals, where we request absolute minimums and emphasize that even a non-detection will lead to publishable science in such and such a way.
Getting over 60 orbits to point at a blank field would have been frankly impossible through the regular time allocation process, not because the science wasn't excellent, not because it wouldn't be recognized as excellent, but because it would crowd out other science that could be done with far fewer orbits per project.
The telescope administrators explicitly recognized this problem when they set up the Director's Discretionary Time process (and this is common to all telescopes now) - sometimes you need someone with the authority to just roll the dice on a long shot.
[1] https://www.stsci.edu/contents/newsletters/2019-volume-36-is...
This sort of proposal pressure (over 9:1 oversubscription) leads to very conservative proposals, where we request absolute minimums and emphasize that even a non-detection will lead to publishable science in such and such a way.
Getting over 60 orbits to point at a blank field would have been frankly impossible through the regular time allocation process, not because the science wasn't excellent, not because it wouldn't be recognized as excellent, but because it would crowd out other science that could be done with far fewer orbits per project.
The telescope administrators explicitly recognized this problem when they set up the Director's Discretionary Time process (and this is common to all telescopes now) - sometimes you need someone with the authority to just roll the dice on a long shot.
[1] https://www.stsci.edu/contents/newsletters/2019-volume-36-is...
Exactly, this is exactly why I decided not to pursue academia.
Too many times I heard things along the lines of getting "low hanging fruit" to get "published" and that "don't try that you won't ever graduate". Why is graduating and publishing papers and tenure and theses the goal of academia, instead of trying the highest possible risk things that even companies wouldn't want to risk? Why isn't academia about doing the most utterly crazy things possible in the name of advancing science for civilization?
Too many times I heard things along the lines of getting "low hanging fruit" to get "published" and that "don't try that you won't ever graduate". Why is graduating and publishing papers and tenure and theses the goal of academia, instead of trying the highest possible risk things that even companies wouldn't want to risk? Why isn't academia about doing the most utterly crazy things possible in the name of advancing science for civilization?
You're absolutely right. What's good for civilization is to advance scientific understanding and knowledge. To take risks, because sometimes they pan out! So go on, pour resources into a thousand crazy ideas. Something will work out eventually.
Yet, what's good for the academic? Each effort costs potentially years of your life. A great discovery will catapult you to the stars, a small one will advance your career, and a negative finding does nothing. You're not alone, you have peers competing for the next round of funding, tenured position, or residency. There are literally never enough to go around, and each will judge applicants in part on their record of results.
I think you're describing a conflict between what's valuable for a system at scale and what's valuable for individual actors within it.
Yet, what's good for the academic? Each effort costs potentially years of your life. A great discovery will catapult you to the stars, a small one will advance your career, and a negative finding does nothing. You're not alone, you have peers competing for the next round of funding, tenured position, or residency. There are literally never enough to go around, and each will judge applicants in part on their record of results.
I think you're describing a conflict between what's valuable for a system at scale and what's valuable for individual actors within it.
If you want to find nothing without hurting your career, spend your time reproducing other people's results. Lots of the time you will find what they found, which doesn't help your career much. But sometimes you'll find frauds or mistakes, and that will help your career and our civilization quite a lot.
That's very optimistic. More likely you will be disliked by your peers for, in their view, actively trying to demolish their reputation. There's a lot of politics in academia and it's way better to just try to be friends and never say bad words of other peoples works. Live and let live. Is this good for the public and "Science" in capital letters? No. But it's how it is.
Perhaps it is, but you don't have to reproduce the work of your direct colleagues.
Specialties are usually small worlds where everyone knows everyone, reviews, funding grants recommendations flow between them, as do postdocs and graduate students. Stirring up as little water as possible and playing into the hands of the others is incentivized.
This is highly dependent on the discipline and particular field.
For topics with a large number of practicing labs that make use of relatively accessible tooling you might be able to pull off such an approach.
Other fields require customized, incredibly expensive instrumentation. Physics and certain areas of biomedical research are examples of this. It's not uncommon that fewer than ten labs in the entire world will have the capability to perform a particular highly specialized technique.
Even in the largest fields though, it will be your peers reviewing your grant applications at the end of the day.
For topics with a large number of practicing labs that make use of relatively accessible tooling you might be able to pull off such an approach.
Other fields require customized, incredibly expensive instrumentation. Physics and certain areas of biomedical research are examples of this. It's not uncommon that fewer than ten labs in the entire world will have the capability to perform a particular highly specialized technique.
Even in the largest fields though, it will be your peers reviewing your grant applications at the end of the day.
It’s a question of resource allocation too. To advance science, you want to give more resources and control to people who can potentially make the best discoveries and breakthroughs. How do you find these people? Currently, it seems to be this competition with papers published on the best journals with high citation numbers.
Imagine the world had a single supercomputer, and somebody wanted 100% utilization for those hundred hours to, say, train a neural net to play donkey kong. It's not a huge cost, given the expected lifetime of the resource, but to everybody else waiting in the queue, it would be quite the opportunity cost.
But you don’t sum up all the other things for opportunity cost, you take the single max value. In other words, the opportunity cost doesn’t care about how many other people were waiting, it cares only about how much useful results the best alternative proposal would have gotten with the same amount of hours.
That's an inaccurate picture of resource allocation. 100 hours of a globally unique resource could satisfy 100 1-hour demands. You sum those.
That would be one proposal - give 1 hour to 100 different groups.
What you don’t do is sum the 10000 different requests, nor the 100 requests that also want to use 100 hours each.
What you don’t do is sum the 10000 different requests, nor the 100 requests that also want to use 100 hours each.
This is increasingly common across numerous fields. Certainly in academia, but also in corporate R&D, investing, venture capital, military procurement, etc.
Novel trials are big risks, are institutional (or worse, multi-institutional), and searcch spaces are large, well-picked-over, and huge gains improbabble. Though aversion to novelty is a long-standing behaviour, see "Resistances to the Adoption of Technological Innovations", by Bernhard J. Stern (1937):
https://archive.org/details/technologicaltre1937unitrich/pag...
Markdown https://pastebin.com/raw/Bapu75is
Novel trials are big risks, are institutional (or worse, multi-institutional), and searcch spaces are large, well-picked-over, and huge gains improbabble. Though aversion to novelty is a long-standing behaviour, see "Resistances to the Adoption of Technological Innovations", by Bernhard J. Stern (1937):
https://archive.org/details/technologicaltre1937unitrich/pag...
Markdown https://pastebin.com/raw/Bapu75is
I remember the first time I saw the deep field image. It blew my mind then and still does today. I had no idea it was a controversial experiment at the time.
I have a sense that the article is presenting things in a more dramatic way than how it really occurred:
> So, with his job perhaps on the line, Williams went off, put together a small team of post-docs, and did exactly as he’d planned. For 100 hours, between Dec. 18 and 28, Hubble stared at a patch of sky near the Big Dipper’s handle that was only about 1/30th as wide as the full moon. In total, the telescope took 342 pictures of the region, each of which was exposed for between 25 and 45 minutes. The images were processed and combined, then colored, and 17 days later, released to the public.
I mean, each image was only exposed for 25-45 minutes. If the full hundred hours was such a huge risk, why not take, like, 5-10 photos first to see if you get much of anything? Seems like they would have been able to know pretty early on whether it was going to be worth it.
> So, with his job perhaps on the line, Williams went off, put together a small team of post-docs, and did exactly as he’d planned. For 100 hours, between Dec. 18 and 28, Hubble stared at a patch of sky near the Big Dipper’s handle that was only about 1/30th as wide as the full moon. In total, the telescope took 342 pictures of the region, each of which was exposed for between 25 and 45 minutes. The images were processed and combined, then colored, and 17 days later, released to the public.
I mean, each image was only exposed for 25-45 minutes. If the full hundred hours was such a huge risk, why not take, like, 5-10 photos first to see if you get much of anything? Seems like they would have been able to know pretty early on whether it was going to be worth it.
> If the full hundred hours was such a huge risk, why not take, like, 5-10 photos first to see if you get much of anything? Seems like they would have been able to know pretty early on whether it was going to be worth it.
This has been answered already but just to pull some threads together - the suggestion to take a few exposures first and see what comes out is precisely backwards. They already knew, going into it, that what they were looking for was at the limits of sensitivity, so nothing would show up until they accumulated enough observing time.
In the absence of systematic effects, our signal to noise ratio improves as the square root of integration time. Think of a bucket accumulating photons - the signal accumulates in linear proportion to the integration time, while the RMS fluctuations increase as the square root of the integration time, so the signal to noise ratio improves as T/sqrt(T) = sqrt(T).
So the idea was to accumulate enough exposure that the faint galaxies would become visible at the telescope performance limits - can't get to something scientifically useful by imaging only the first few exposures. It might have made a pretty enough picture, sure, but not an informative one, compared to what we could already do from huge ground-based facilities.
This has been answered already but just to pull some threads together - the suggestion to take a few exposures first and see what comes out is precisely backwards. They already knew, going into it, that what they were looking for was at the limits of sensitivity, so nothing would show up until they accumulated enough observing time.
In the absence of systematic effects, our signal to noise ratio improves as the square root of integration time. Think of a bucket accumulating photons - the signal accumulates in linear proportion to the integration time, while the RMS fluctuations increase as the square root of the integration time, so the signal to noise ratio improves as T/sqrt(T) = sqrt(T).
So the idea was to accumulate enough exposure that the faint galaxies would become visible at the telescope performance limits - can't get to something scientifically useful by imaging only the first few exposures. It might have made a pretty enough picture, sure, but not an informative one, compared to what we could already do from huge ground-based facilities.
This is a decent and sensible question IMO, barkingcat (downthread) provides a reasoned answer that seems to fit, but the question is good .. so why did the person feel the need to use a throwaway, and why is it downvoted. Unlike other questions it doesn't appear to be the sort of thing one ignorant of the answer could readily google for.
I know, we're not supposed to complain about downvotes but it just makes me sad that we - as a community - don't value honest questions.
I know, we're not supposed to complain about downvotes but it just makes me sad that we - as a community - don't value honest questions.
I'm sure they did start stacking as soon as they got the images. From a statistical perspective, 100 hr is roughly 3x better than 10 hr.
If they found nothing in the first 5-10 images, what do you imagine they would do? Telescope scheduling is a very tricky business, not one that lets you change courses too quickly.
Schedule the 5-10 mins, then schedule again for later.
The amount of programming and orbital changes needed for this is not feasible.
For the hubble to point at something, I'd imagine it needed to station-keep and burn some hydrazine.
If you did infinite numbers of 5-10 min studies, you'd burn right out of the fuel store of a spacecraft before you'd get anything done.
From what I hear, hubble telescope times are scoped out, planned out a year or several years in advance - the telescopes and scientific instruments need to be programmed, the spacecraft needed to be moved/pivoted to aim at the right part of space, communications times needs to be booked with receivers/ground stations across the entire Deep Space Network so you can receive the data.
It's nontrivial - if you booked 5-10 min at a time you'd have wasted your most precious resource.
https://eyes.nasa.gov/dsn/dsn.html
For the hubble to point at something, I'd imagine it needed to station-keep and burn some hydrazine.
If you did infinite numbers of 5-10 min studies, you'd burn right out of the fuel store of a spacecraft before you'd get anything done.
From what I hear, hubble telescope times are scoped out, planned out a year or several years in advance - the telescopes and scientific instruments need to be programmed, the spacecraft needed to be moved/pivoted to aim at the right part of space, communications times needs to be booked with receivers/ground stations across the entire Deep Space Network so you can receive the data.
It's nontrivial - if you booked 5-10 min at a time you'd have wasted your most precious resource.
https://eyes.nasa.gov/dsn/dsn.html
Hubble points via gyroscopes, not thrusters! But they are slow, so that's part of why you need to schedule things well. YouTube video explaining how it points: https://www.youtube.com/watch?v=qEZI9DxIQss
Also, I don't think it needs to change orbital parameters at all for its operation. Station-keeping yea, but I don't think it needs to burn more fuel because of pointing at things.
Also, I don't think it needs to change orbital parameters at all for its operation. Station-keeping yea, but I don't think it needs to burn more fuel because of pointing at things.
The Hubble telescope is not a deep space probe being so close to earth and doesn't use the Deep Space Network to communicate.
The sheer scale on these photos is amazing. Seeing galaxies strewn around like marbles is very humbling.
I hope there are more plans for deep space photos. I wonder what a telescope on the other side of the moon could capture.
I hope there are more plans for deep space photos. I wonder what a telescope on the other side of the moon could capture.
Other side of the Moon would impose unnecessary communication complexities without much optical benefit. Earth-Sun L2 point is much better because Earth's shadow blocks most of heat from the Sun, plus the probe needs heat shield only on one side to block remains of heat from Sun, Earth and Moon.
See: https://en.wikipedia.org/wiki/James_Webb_Space_Telescope#Sun...
building on the surface of the moon is not without benefit. as a static location, it would be much easier to build larger sensors with larger mirrors, rather than having to build one giant thing and hope it deploys safely. You could build an arbitrarily large-sized mirror. Or, you could build large radio telescopes that do not need to contest with the noise of the earth's atmosphere.
all spectra are important for astrological observations—there is a serious lack of radio observations made with large telescopes outside of the earth's atmosphere in particular.
NASA has funded an early study into the feasibility of building such a telescope. https://www.nasa.gov/directorates/spacetech/niac/2020_Phase_...
all spectra are important for astrological observations—there is a serious lack of radio observations made with large telescopes outside of the earth's atmosphere in particular.
NASA has funded an early study into the feasibility of building such a telescope. https://www.nasa.gov/directorates/spacetech/niac/2020_Phase_...
Absolutely, but that still is far much more investment into infrastructure. However the Moon surface is still too hot for precise IR observations.
I'm sure it is on the list for JWST. I suspect Spitzer must have already attempted the same thing.
Being on the other side of the Moon, alone, isn't likely to make a huge difference in image depth.
Being on the other side of the Moon, alone, isn't likely to make a huge difference in image depth.
And frightening. Such photos really bring home the Great Silence. All of those specks which are entire galaxies, and not the single slightest sign of intelligent life anywhere, ever. The marbles roll on just as they have for billions and billions of years and will go on rolling for billions to come, dead pieces of inert matter tracing out their gravitational trajectories and burning as predicted.
>All of those specks which are entire galaxies, and not the single slightest sign of intelligent life anywhere, ever.
You say that as if we could tell with any certainty, at that scale. There could be interstellar civilizations spanning several of those galaxies and uncountable intelligent civilizations that simply never pursued space travel or the constant accelerated curve of energy consumption and colonization we assume they would, only because we ourselves would.
We wouldn't know, we don't even really know what we're looking for, and the universe is so vast that even if we did, we'd be all but certain to blink and miss it.
You say that as if we could tell with any certainty, at that scale. There could be interstellar civilizations spanning several of those galaxies and uncountable intelligent civilizations that simply never pursued space travel or the constant accelerated curve of energy consumption and colonization we assume they would, only because we ourselves would.
We wouldn't know, we don't even really know what we're looking for, and the universe is so vast that even if we did, we'd be all but certain to blink and miss it.
It isn't even clear that the pursuit of colonization we want to pursue is even possible. It takes a lot of energy to do those things and there are limits to how much we can safely use. We are already worried about global warming despite not having a colony to support.
Yea, but they would have to blink a significant portion of their galaxy for us to notice.
The top of our capabilities is indirect planet discovery. So alien civilization would need to affect ceartain stars on a scale that a planet does and make it look not natural, like prime number periods or something.
The top of our capabilities is indirect planet discovery. So alien civilization would need to affect ceartain stars on a scale that a planet does and make it look not natural, like prime number periods or something.
This is like being in a plane at cruising altitude, looking down at the ocean, and declaring there's zero signs of life, so the ocean must be dead.
Whales would be visible, along with all the life chemicals, so the analogy isnt that great.
I've flown in planes a handful of times, looked down at the ocean on plenty of opportunities, and never observed any whales. I'd say the analogy is perfectly great.
If the water was as transparent as space, whales and large schools of fish would certainly be apparent.
Space isn't quite transparent, and a closer analogy would be to ask if you can spot bacteria and other microorganisms because something sentient the size of a whale
"scaled up to space" would be unrecognizable as such to us.
> Space isn't quite transparent
On Earth scale it is for all practical purposes.
On Earth scale it is for all practical purposes.
Space whales!
A rather apt analogy, because you can see countless signs of non-equilibrium behavior, chemicals, heat, and other things (you really have never seen any, say, birds while flying?) that tells you you are not on a planet devoid of life.
Assume we are starting with, IIRC, ballpark 14 billion years since the big bang.
Well, to get to life, we have to have chemical elements more than just the hydrogen, helium, and a little lithium that came directly from the big bang. So for carbon, oxygen, ..., iron, have to have some big stars form, burn, and explode.
So those galaxies from 12 billion years ago didn't have much time -- ballpark only 2 billion years -- to form the elements of the periodic table.
Coming at it from our end, IIRC our planet and solar system are about 5 billion years old.
Give it, after the big bang, 4 billion years to the periodic table and another 5 billion years for life. So, that's 9 billion years, 5 billion years ago.
So don't expect much in Little Green Men ET from more than 5 billion years ago.
Since we started 5 billion years ago, we are ballpark only second generation life in this universe.
Net, mostly what's in the Hubble deep field images is too old to have much in life (anything like ours). To have a shot at seeing life, don't look back more than ballpark 5 billion years.
Since stars are burning out and the universe is expanding, are we also about the last generation of life?
Yup, it's amazing to look back 12 billion years, to see galaxies already there, with quasars and, thus, likely supermassive black holes. Amazing to guess how such big black holes formed so soon. Lots more that's amazing. Still for life, only look back about 5 billion years.
Disclosure: I'm not an astronomer!
Well, to get to life, we have to have chemical elements more than just the hydrogen, helium, and a little lithium that came directly from the big bang. So for carbon, oxygen, ..., iron, have to have some big stars form, burn, and explode.
So those galaxies from 12 billion years ago didn't have much time -- ballpark only 2 billion years -- to form the elements of the periodic table.
Coming at it from our end, IIRC our planet and solar system are about 5 billion years old.
Give it, after the big bang, 4 billion years to the periodic table and another 5 billion years for life. So, that's 9 billion years, 5 billion years ago.
So don't expect much in Little Green Men ET from more than 5 billion years ago.
Since we started 5 billion years ago, we are ballpark only second generation life in this universe.
Net, mostly what's in the Hubble deep field images is too old to have much in life (anything like ours). To have a shot at seeing life, don't look back more than ballpark 5 billion years.
Since stars are burning out and the universe is expanding, are we also about the last generation of life?
Yup, it's amazing to look back 12 billion years, to see galaxies already there, with quasars and, thus, likely supermassive black holes. Amazing to guess how such big black holes formed so soon. Lots more that's amazing. Still for life, only look back about 5 billion years.
Disclosure: I'm not an astronomer!
>Since stars are burning out and the universe is expanding, are we also about the last generation of life?
Red dwarfs will still be burning a trillion years from now. The flare stars among them will only become more stable with time. I'm not sure what the prospects for interstellar travel will be by then, though.
Red dwarfs will still be burning a trillion years from now. The flare stars among them will only become more stable with time. I'm not sure what the prospects for interstellar travel will be by then, though.
> Still for life, only look back about 5 billion years.
This contradicts the clue of the article. Sometimes it is worth to step back and try something unordinary, especially in area where our assumptions are so weak - the Universe.
This contradicts the clue of the article. Sometimes it is worth to step back and try something unordinary, especially in area where our assumptions are so weak - the Universe.
Even if we wanted to tell the universe we existed, it would take too much energy to shoot out a strong enough signal. We would have to eat the sun to do that :)
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Best article I've read in a long long time.
> For 100 hours, between Dec. 18 and 28, Hubble stared at a patch of sky near the Big Dipper’s handle that was only about 1/30th as wide as the full moon. In total, the telescope took 342 pictures of the region, each of which was exposed for between 25 and 45 minutes.
How did this work? 342 pictures at 25 minutes each is already well over 100 hours. At 45 minutes, it'd be 256 hours.
How did this work? 342 pictures at 25 minutes each is already well over 100 hours. At 45 minutes, it'd be 256 hours.
The Hubble Telescope has multiple cameras and sensors.
Indeed, the math doesn't pencil out.
I don't know, but I'd hazard a guess that the image is 100 hr deep on multiple tiles.
The dataset spans 10 days, which is 240 hr.
I don't know, but I'd hazard a guess that the image is 100 hr deep on multiple tiles.
The dataset spans 10 days, which is 240 hr.
The telescope's orbital period and the relative positions of the earth and the sun will affect how the exposures are scheduled.
I went looking for more detailed information -- It appears they are open enough with the data that you can see exactly how the exposures were taken. Assuming what I found is right and that someone could make sense of the data. There are postscript files listing activity for each of the 10 days, but I am not exactly sure what we're looking at.
https://www.stsci.edu/ftp/science/hdf/project/project.html
I went looking for more detailed information -- It appears they are open enough with the data that you can see exactly how the exposures were taken. Assuming what I found is right and that someone could make sense of the data. There are postscript files listing activity for each of the 10 days, but I am not exactly sure what we're looking at.
https://www.stsci.edu/ftp/science/hdf/project/project.html
Here you go:
https://www.stsci.edu/ftp/science/hdf/project/scheduling.htm...
Observations run from 352:16 to 362:19.
Filter Nexp hours
F300W 100 48.93
F450W 62 36.52
F606W 77 34.94
F814W 49 34.86
https://www.stsci.edu/ftp/science/hdf/project/scheduling.htm...
Observations run from 352:16 to 362:19.
Filter Nexp hours
F300W 100 48.93
F450W 62 36.52
F606W 77 34.94
F814W 49 34.86
Possibly counting images using different sensors as separate exposures, even if they're taken during overlapping time intervals
Could it be 100hrs of night sky?
That makes no sense for a satellite in orbit around the earth outside of the atmosphere. It would never point at the sun. The only issue is that the earth would periodically occlude the area of observation.
Ha! I just ordered a custom skate deck with these images on the bottom.
I'm sorry, I haven't read the article, maybe it's explained there, but as far as I understand by 100 hours they mean that the telescope was sitting there for 100 hours exposed open like a camera, right? How come the image is so sharp then? Wouldn't all those galaxies be constantly moving and end up blurred in a photo?
So there are two things you do to take very long "exposures" like this for astrophotography:
1. You put the telescope on a motorized mount that rotates the telescope exactly counter to the rotation of the Earth (or I guess its orbit in the case of Hubble). This cancels out most of the blurry star trails you get from the Earth's rotation causing the stars to move across your frame.
2. For particularly long exposures, you take a series of separate photos (each of which is probably done using step 1). Then you "stack" those in software by aligning all of the images to maximize their sharpsness. There is software that will do this for you automatically. Stacking helps correct for thermal noise and other imperfections and non-linearities that photon sensors have when collecting for a really long time.
It's a good question.
1. You put the telescope on a motorized mount that rotates the telescope exactly counter to the rotation of the Earth (or I guess its orbit in the case of Hubble). This cancels out most of the blurry star trails you get from the Earth's rotation causing the stars to move across your frame.
2. For particularly long exposures, you take a series of separate photos (each of which is probably done using step 1). Then you "stack" those in software by aligning all of the images to maximize their sharpsness. There is software that will do this for you automatically. Stacking helps correct for thermal noise and other imperfections and non-linearities that photon sensors have when collecting for a really long time.
It's a good question.
Hubble is in space. They just pointed it somewhere and said “don’t move” (well, multiple times and stacked, but the effect is the same). The galaxies themselves are so far away their own motion is way less than a single pixel.
Yes but isn't Hubble moving? Or is it in a fixed position in space?
There’s no such thing as a fixed position in space.
The motion of Hubble (and basically everything inside the Milky Way) relative to the galaxies in that picture is ~250,000 km/s, or 0.83 c.
At this speed, it would take ~100,000 years for the galaxy to move its own length, and even then the movement would be in a direction which doesn’t cause much blur.
http://www.wolframalpha.com/input/?i=12e9%20light%20years%20...
The motion of Hubble (and basically everything inside the Milky Way) relative to the galaxies in that picture is ~250,000 km/s, or 0.83 c.
At this speed, it would take ~100,000 years for the galaxy to move its own length, and even then the movement would be in a direction which doesn’t cause much blur.
http://www.wolframalpha.com/input/?i=12e9%20light%20years%20...
To be clear I meant is it in a fixed position relative to earth? I know if you’re photographing galaxies, they move so little relative to us that they might as well be stationary. But isn’t Hubble in an orbit?
Motion on the scale of “orbit” is utterly irrelevant on these scales. Rotation around an internal axis is the only thing which matters, and that’s something space telescopes are designed around.
"Bob was right, I was wrong. The use of that discretionary time was a courageous thing,"
This is such a powerful statement from Rob Kirschner. It is science at it's best. Someone (rightfully) opposing an experiment, being incorrect and admitting, without reluctance, shame or regrets that they were wrong.
At the time, Bob's idea was by all available information questionable. But it was right for him to persevere, it was right that he had to face and overcome opposition and it is right that the opposition gracefully admits that Bob was right :)
This is such a powerful statement from Rob Kirschner. It is science at it's best. Someone (rightfully) opposing an experiment, being incorrect and admitting, without reluctance, shame or regrets that they were wrong.
At the time, Bob's idea was by all available information questionable. But it was right for him to persevere, it was right that he had to face and overcome opposition and it is right that the opposition gracefully admits that Bob was right :)
This interview with Kirshner is a good read as well: https://www.aip.org/history-programs/niels-bohr-library/oral... And a reminder that science is not generally moved forward by strokes of brilliance, but by a whole bunch of people grinding at the fuzzy edge until the picture becomes a little more clear.
Spectacularly appropriate metaphor - thanks for that.
Kuhns distinction between normal and revolutionary science might be interesting to you:
https://en.wikipedia.org/wiki/Normal_Science
Great quote. Also unintentionally (I think) humorous, given the manufacturing problem with Hubble referred to in the article was slightly inaccurate grinding of the lens' edges.
"Bob was right" would be a good framed reminder
Is "Praise Bob" still a thing?
Well, now that I’ve literally just now returned to this mess of a planet I would sure hope so!
As an Aussie, this hilariously augments a phrase used commonly here: "Bob's your uncle"
(meaning roughly: "and there it is" / "and there you have it")
Even more hilariously, I have an uncle Bob.
(meaning roughly: "and there it is" / "and there you have it")
Even more hilariously, I have an uncle Bob.
I seem to remember back in the 1990s reading a research paper about a theorem proover that used the phrase "And Bob's your uncle" to indicate success. A query was initiated by typing "Is that a fact".
Also used in the UK. Bob can be an auntie too.
I suppose; it's certainly better than stubbornly holding one's ground after one is proven wrong.
But I think the courage Bob showed in the first place is much more praiseworthy. He actually had to put his butt on the line for this, admitting someone was right after the fact does not usually require that.
But I think the courage Bob showed in the first place is much more praiseworthy. He actually had to put his butt on the line for this, admitting someone was right after the fact does not usually require that.
Reminds me of Malcolm Gladwell's "pull the goalie" podcast. https://medium.com/the-post-grad-survival-guide/lessons-for-...
I think it's a good lesson to learn, in general, that intuition and popular choices are often wrong or at least sub optimal. But I suspect that the popular sub-optimal path is taken for pragmatic reasons. More specifically to teaching, I have recently being putting together lesson plans for coding/robotics workshops and I suspect part of the reason for a less experimental experience is that it is easier to plan than a less on-rails teaching experience. This makes me think that at least part of popular wisdom is simply that the sub-optimal popular choice might be good enough given insufficient resources to implement the truly optimal choice.
Not to make a reddit comment, your comment is insightful but can also be summed up with: "nobody ever got fired for buying IBM".
The path of least resistance is definitely a draw, and there is incredible business value lost pursuing it.
The path of least resistance is definitely a draw, and there is incredible business value lost pursuing it.
Probably it’s a perspective issue, but galaxies look relatively close to each other, is that the case?
I mean they look relatively close compared to their size, in contrast our solar system’s bodies are really far away from each other (of course relatively).
I mean they look relatively close compared to their size, in contrast our solar system’s bodies are really far away from each other (of course relatively).
They are far apart because they are different distances away from us. E.g. two galaxies that look right next to each other in the image could be 5 billion and 6 billion light years away from us, which means 1 billion light years away from each other. Hover over the galaxies in the image here to see the distances (warning: makes sound): https://apod.nasa.gov/apod/ap180305.html
They are. Stars are of the order of thousands of star-diameters apart from each other, while galaxies are of the order tens of galaxy-diameters apart.
> Stars are of the order of thousands of star-diameters apart from each other
no. they're millions of star-diameters apart.
https://en.wikipedia.org/wiki/Solar_radius compare it to a light year. note that the nearest star is 4 something light years away. the average is about 5 ly.
> while galaxies are of the order tens of galaxy-diameters apart.
i think that's low, but harder to define.
no. they're millions of star-diameters apart.
https://en.wikipedia.org/wiki/Solar_radius compare it to a light year. note that the nearest star is 4 something light years away. the average is about 5 ly.
> while galaxies are of the order tens of galaxy-diameters apart.
i think that's low, but harder to define.
You are absolutely right. I was too quick trying to convert between millions of km to lightyears in my head.
Remember it's 3d; they're not arranged on a single plane.
Average distance between galaxies is 10-100 times the diameter of the average galaxies.
Andromeda for naked eye is a smudge six time bigger than the moon (3.0 degrees across).
Andromeda for naked eye is a smudge six time bigger than the moon (3.0 degrees across).
I found it hard to believe that Andromeda would be six times larger in the night sky than the moon, so I searched online and discovered this article showing what the galaxy would look like if it were brighter: https://petapixel.com/2014/12/08/photos-night-sky-look-like-...
Wow. TIL.
Wow. TIL.
You can see it with the naked eye in a very dark place. It looks like a big brighter smudged area, a little off the plane of the milky way. And it does appear a lot bigger than the moon.
Since we seem to have a good discussion here, there's something I've always wanted to know.
If I understand correctly, the universe is approximately 13.8 billion years old. As is mentioned frequently when staring at deep space, we are looking at the universe not as it is, but as it was, since it takes so long for the light to travel to us. Some objects in the Hubble Deep Field are over 9 billion years old, and some within 1 billion years of the beginning of the universe.
My question, as best I am able to ask it, is assuming the big bang theory is true, how can it be that we on Earth can be looking at something simultaneously so old and so far away? If everything originated from the same point, how can it be that we pick an object in the sky and say "that is what the object looked like 12 billion years ago"? Doesn't it beg the question, "well then where were we 12 billion years ago?" As in, how can we be here, observing something close to the beginning of time? Didn't both objects start at the same place?
I hope that makes sense.. Articles and videos much appreciated
If I understand correctly, the universe is approximately 13.8 billion years old. As is mentioned frequently when staring at deep space, we are looking at the universe not as it is, but as it was, since it takes so long for the light to travel to us. Some objects in the Hubble Deep Field are over 9 billion years old, and some within 1 billion years of the beginning of the universe.
My question, as best I am able to ask it, is assuming the big bang theory is true, how can it be that we on Earth can be looking at something simultaneously so old and so far away? If everything originated from the same point, how can it be that we pick an object in the sky and say "that is what the object looked like 12 billion years ago"? Doesn't it beg the question, "well then where were we 12 billion years ago?" As in, how can we be here, observing something close to the beginning of time? Didn't both objects start at the same place?
I hope that makes sense.. Articles and videos much appreciated
What blows my mind even more than that is the fact that the universe is apparently 93 billion light years in diameter despite being only 14 billion years old. Intuitively, I'd think that the radius of the universe would be smaller than the age of the universe. Stuff in the universe would go outward more slowly than light in the universe would go outward, because stuff moves slower than light. Apparently that's not the case. Space and time are weird.
My understanding is that the expansion of space/time can exceed the speed of light because space time is what light travels through. Nothing says that two points can't move apart faster than the speed of light, just that information between them can't be shared faster than the speed of light.
I don't understand what it means for points to move apart faster than the speed of light. I understand speed of a thing to be change with respect to space, so what does speed of space mean? Naively, I'd define it to be zero. If I stretch a ruler out, the 1ft mark hasn't moved with respect to the 1ft mark. I can say otherwise by comparing the ruler to what's around it. If the ruler is literally everything, we can only measure the ruler with respect to itself. I'd define measurement as with respect to the ruler (the ruler is spacetime). I know I'm wrong, but can't figure out why. Any help?
Look up the expanding balloon analogy.
With that analogy, the balloon would be the ruler in my analogy, which leads me back to the original questions. Using the balloon analogy, if you have a normal balloon in 3D euclidean space, you can measure/define the expansion easily. Without that, what can you do?
You could define some physical process on the balloon as distance and time, like light moving and atoms vibrating, and call that our ruler. Then measure intrinsic properties like curvature? If hypothetically the speed of light instantly dropped by 5% (with respect to existing objects' distances, I guess), do you just define those objects as instantly 5% further apart now, or do you you say something like the speed of light changed? Then there'd be similar questions about changes in how we define time. This is fun to think about.
You could define some physical process on the balloon as distance and time, like light moving and atoms vibrating, and call that our ruler. Then measure intrinsic properties like curvature? If hypothetically the speed of light instantly dropped by 5% (with respect to existing objects' distances, I guess), do you just define those objects as instantly 5% further apart now, or do you you say something like the speed of light changed? Then there'd be similar questions about changes in how we define time. This is fun to think about.
When the universe has a size, what is outside of it?
Chicken.
Short answer: We don't know
Longer answer: Maybe nothing. Maybe it's nonsensical to think of something as being outside of the universe - as it expands, it creates space where there was none. Maybe a true vacuum that our universe is floating through. Maybe other universes. Maybe something else.
We might not be able to ever know the answer to this question - the laws of physics might prevent us from being able to decipher it.
Longer answer: Maybe nothing. Maybe it's nonsensical to think of something as being outside of the universe - as it expands, it creates space where there was none. Maybe a true vacuum that our universe is floating through. Maybe other universes. Maybe something else.
We might not be able to ever know the answer to this question - the laws of physics might prevent us from being able to decipher it.
Universe expansion was huge, immediately. That's all.
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Imagine that it is the 17th century. We are both in London, and you tell me that you will be in Mumbai in six months. The same night, I write a letter to you, addressed to Mumbai. Six months later, both you and the letter arrive, and by opening it you are exposed to my mindset as it was six months ago.
Hope that helped a little bit..
Hope that helped a little bit..
I won't pretend to understand the answer well enough to give a clear answer. Instead I'll highly recommend an illustrated version of Stephen Hawking's Brief History of Time to dig deeper into this question. I personally find that big questions like this really do require more than an article or video.
If you run the big bang model far enough into the past, you arrive at a singularity. Near that point, relativity starts to break down, and we don't really know what physics looks like.
For unrelated reasons, we cannot see back past further than about 10^-6 seconds after the big-bang, because the universe prior to that point was so hot and dense that photons would be reabsorbed almost immedietly.
Once you avoid everything being in literally the same place, the problem just becomes having the photon move towards us faster than the expansion of the universe.
For unrelated reasons, we cannot see back past further than about 10^-6 seconds after the big-bang, because the universe prior to that point was so hot and dense that photons would be reabsorbed almost immedietly.
Once you avoid everything being in literally the same place, the problem just becomes having the photon move towards us faster than the expansion of the universe.
Not a physicist or even anything more than a bachelor's in anything - though this is my understanding.
Many depictions of the big bang show the entire universe - something which may not have a finite volume - collapsing to an entire point.
It might be more illustrative if you imagine when you look at one of those drawings that it is in fact "merely" depicting all of the space within a finite volume today collapsing to a particular point in the past corresponds to the big bang. Conversely, things arbitrarily close together in the big bang can be arbitrarily far away now. There is no "center" of the universe, it's more like the shriveled up balloon analogy. Draw a bunch of dots on a blown up balloon and let it deflate, everything gets closer together but no one point is the center. So it doesn't make sense to ask "where were we 12 billion years ago?" The answer is: closer to everything we can see.
This explanation corresponds to a universe whose shape has zero curvature or negative curvature. WMAP and other experiments have suggested the curvature of the universe is very close to zero, but even a slight deviation above or below has dramatically different implications.
Many depictions of the big bang show the entire universe - something which may not have a finite volume - collapsing to an entire point.
It might be more illustrative if you imagine when you look at one of those drawings that it is in fact "merely" depicting all of the space within a finite volume today collapsing to a particular point in the past corresponds to the big bang. Conversely, things arbitrarily close together in the big bang can be arbitrarily far away now. There is no "center" of the universe, it's more like the shriveled up balloon analogy. Draw a bunch of dots on a blown up balloon and let it deflate, everything gets closer together but no one point is the center. So it doesn't make sense to ask "where were we 12 billion years ago?" The answer is: closer to everything we can see.
This explanation corresponds to a universe whose shape has zero curvature or negative curvature. WMAP and other experiments have suggested the curvature of the universe is very close to zero, but even a slight deviation above or below has dramatically different implications.
Our galaxy and that galaxy were already far away from each other 12 billion years ago, even if they started at the same place 13.8 billion years ago.
The photons have spent 12bn years travelling through the universe, and they’re just hitting the Hubble telescope now.
Both objects started moving at the same time but at different speeds and in different directions- on top of this the universe itself is also expanding, so the gaps between galaxies is actually growing, meaning it takes longer for the photons to get here
Both objects started moving at the same time but at different speeds and in different directions- on top of this the universe itself is also expanding, so the gaps between galaxies is actually growing, meaning it takes longer for the photons to get here
Well, let's try to explain general relativity, shall we?
First of all, the universe is expanding. A good visual is to paint stuff on the surface of a balloon. Everything on the balloon started off close together. But as the balloon expands, things on the surface of that ballon get farther apart. So it is with the universe.
Where did this happen? Everywhere, and nowhere. The balloon is an analogy for the structure of the universe. The balloon exists in a 3-D world at a time and place. But all notions of time and place are defined within the structure of the universe. So I'm describing what happened everywhere. All places used to be close. And now they are not.
Now the Big Bang theory is this. If you play that tape backwards, everything that we can see was once really close together. But still had all the same stuff. So the universe was a hot, dense place. Then it began expanding, and got large and cool and fairly empty.
So if everything used to be close, why does light only now reach us from somewhere that wasn't that far away originally? Well look at light as being like an ant crawling on the surface of the balloon. At first your journey doesn't look far, but the balloon starts expanding and the trip gets longer. You keep traveling and it gets longer still. That's exactly the plight of light from the early universe.
Did that help?
First of all, the universe is expanding. A good visual is to paint stuff on the surface of a balloon. Everything on the balloon started off close together. But as the balloon expands, things on the surface of that ballon get farther apart. So it is with the universe.
Where did this happen? Everywhere, and nowhere. The balloon is an analogy for the structure of the universe. The balloon exists in a 3-D world at a time and place. But all notions of time and place are defined within the structure of the universe. So I'm describing what happened everywhere. All places used to be close. And now they are not.
Now the Big Bang theory is this. If you play that tape backwards, everything that we can see was once really close together. But still had all the same stuff. So the universe was a hot, dense place. Then it began expanding, and got large and cool and fairly empty.
So if everything used to be close, why does light only now reach us from somewhere that wasn't that far away originally? Well look at light as being like an ant crawling on the surface of the balloon. At first your journey doesn't look far, but the balloon starts expanding and the trip gets longer. You keep traveling and it gets longer still. That's exactly the plight of light from the early universe.
Did that help?
I have a very naive question: if everything expands, why aren’t planets also expanding and why isn’t any molecular structure expanding as well? In other words, what does expand the universe yet prevents the planets (and us) from also expanding with it?
I'm definitely no physicist or cosmologist, but my understanding is that we can't detect expansion at the scale of molecules, humans, earth, etc. We only know about it at cosmological scales because we can observe redshifted light over huge distances (millions of light-years). Gravity is postulated to bind matter together strongly enough at smaller distances that expansion does not occur. In other words, it pretty much only happens between galaxy clusters, where gravity is too weak to overpower it.
My pet theory is that the universe isn't expanding. Rather, all the objects in the universe are shrinking. If your ruler is shrinking then it looks like space is expanding. /:-)
Maybe I am wrong, but isn't it the same?
I mean, if everything is shrinking (excepted the distances between galaxies), then it is exactly the same as if the galaxies were spreading in the universe... only the point of view changes right?
Expanding consumes energy. Shrinking releases energy. When object is pooled to another object by gravitation, energy is released, so these objects must shrink to obey law of energy conservation!
Because this expansion is so infinitesimal on that scale as to be negligible. It's about 7%/Gyr, or a billion years for an unbound structure's "space" to grow by 7%. Or about 70 picometers (10^-12) per meter every year. Or in other words, about a water molecule per meter every four years.
At that rate nearly every other force (from chemical bonds to gravity) prevent anything but the largest cosmological structures (like galaxies) from being effected. They simply continue with their system as they always have, and the extra space shows up as distance between galaxies.
At that rate nearly every other force (from chemical bonds to gravity) prevent anything but the largest cosmological structures (like galaxies) from being effected. They simply continue with their system as they always have, and the extra space shows up as distance between galaxies.
> Or in other words, about a water molecule per meter every four years.
That still sounds measurable though. Has there been any multiyear experiments that try to measure something like that?
That still sounds measurable though. Has there been any multiyear experiments that try to measure something like that?
How? Gravity will make all such changes impossible to measure except at galactic scales.
Again any "new space" doesn't stick around where it was created. The atomic forces, chemical forces, and gravity maintain the system distances we are used to.
Again any "new space" doesn't stick around where it was created. The atomic forces, chemical forces, and gravity maintain the system distances we are used to.
Where was gravity when the universe was hot and dense ?
Sometime after around 10^-43 seconds apparently is when it started having effects.
https://www.quora.com/When-did-gravity-first-arise-in-the-un...
https://www.quora.com/When-did-gravity-first-arise-in-the-un...
At this time, it was denser and heavier than any black hole. Why it didn't collapse back then?
I am going to preface this by saying I'm no scientist. I think it is because the expansion velocity is so high. It would be nice to get a definitive answer.
Also, how is space expanding in time when space is already intertwined with time. Is the block universe expanding in meta time ?
Gravity and sub-atomic forces are much stronger at short distances.
The ant analogy helped a lot.
Apparently, the universe expanded much quicker than the speed of light during the big bang. So, for us to see something from 12 billions years ago, it would have to be 12 billion light years away from where we are presently.
Since light travels all directions, if something was older than presumed aged of the universe, statistically speaking, we'd be able to see some of it from here.
Since light travels all directions, if something was older than presumed aged of the universe, statistically speaking, we'd be able to see some of it from here.
I think your question is simply explained by the fact that the universe initially expanded much faster than the speed of light. Then it slowed down. The light has had time (12 billion years) to catch up.
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There's an article in Wikipedia about a galaxy and its relative distance that touches on this: https://en.wikipedia.org/wiki/UDF_423
I stared at nothing. I stared at absolutely nothing and it was everything that I thought it could be.
It seems counter to the fundamentals of science culture that the director just kind of gets 10% of the time without need for approval.
Can anyone cast some light on this?
Can anyone cast some light on this?
You can look at it as the process of becoming director is itself approval for those kind of discetionary choices. When an organization works well, it entrusts power to those who have the judgement to use it well.
If someone needs to get ten different kinds of approvals, are they really a "director" for most meaningful senses of the word?
If someone needs to get ten different kinds of approvals, are they really a "director" for most meaningful senses of the word?
I can't imagine you become director of the hubble telescope without having a significant, long-running track record of astronomical science behind you. The odds of such a person picking something interesting to observe are high.
I thought this was an interesting part of the article that wasn't fully explained - how this was negotiated.
There is some explanation for Director's Discretionary's purpose here in the Call for Proposals (although given that this Deep Field project seems now unlikely to qualify, this might have been retconned):
https://wayback.archive-it.org/all/20080527200338/http://www...
There is some explanation for Director's Discretionary's purpose here in the Call for Proposals (although given that this Deep Field project seems now unlikely to qualify, this might have been retconned):
https://wayback.archive-it.org/all/20080527200338/http://www...
Curious how strongly apparent size correlates to youth.
I am guessing that especially in the extreme deep field,
the distant couple-pixel dots correspond to the back of the room i.e. the oldest/most distant galaxies,
so this is in some real if crude sense looking through a core sample of cosmological time?
I am guessing that especially in the extreme deep field,
the distant couple-pixel dots correspond to the back of the room i.e. the oldest/most distant galaxies,
so this is in some real if crude sense looking through a core sample of cosmological time?
Get around "sign up if you wanna read" modal w/ window.bc.jQuery.fancybox.close(); jQuery('.fancybox-lock,body,html').css({overflow:'scroll'})
how do I use this
We learned new words for things. The decade changed.
The first few pictures came back blurred, and I felt ashamed
For all the cheerful engineers, my father and his tribe.
The second time,
The optics jibed. We saw to the edge of all there is—
So brutal and alive it seemed to comprehend us back.
Smith's father worked on the Hubble telescope, and she would be named US Poet Laureate in 2017. I highly recommend reading her poetic account of this photograph :)
[1]: https://www.poetryfoundation.org/poems/55519/my-god-its-full...
So Bob was right, because Bob was right.
Good learning opportunity here.
We shouldn't think to hard whether he was right or why though.
Good learning opportunity here.
We shouldn't think to hard whether he was right or why though.
“With this achievement, the estimated number of galaxies in the universe had multiplied enormously — to 50 billion, five times more than previously expected,”
It seems that current estimates for this are higher, such as 100 billion in a 2020 article I saw. Anyone have an authoritative scientific source for the best current estimates?
50 billion galaxies (or 100) somehow doesn't actually seem so many. Considering that's on the same scale as the number of people on our tiny space rock. Yes each one has billions of stars inside, but still, we're talking about the entire universe.
Somehow, intuition suggests there must be more "stuff" beyond our observable universe.
It seems that current estimates for this are higher, such as 100 billion in a 2020 article I saw. Anyone have an authoritative scientific source for the best current estimates?
50 billion galaxies (or 100) somehow doesn't actually seem so many. Considering that's on the same scale as the number of people on our tiny space rock. Yes each one has billions of stars inside, but still, we're talking about the entire universe.
Somehow, intuition suggests there must be more "stuff" beyond our observable universe.
I agree....
here's https://phys.org/news/2017-01-universe-trillion-galaxies.htm... where it's 2 trillion. Which is 1 galaxy for every dollar in the US Coronovirus stimulus package or 256 galaxies per person. Which makes it also feel like an approachable number for the amount of galaxies in the universe.
here's https://phys.org/news/2017-01-universe-trillion-galaxies.htm... where it's 2 trillion. Which is 1 galaxy for every dollar in the US Coronovirus stimulus package or 256 galaxies per person. Which makes it also feel like an approachable number for the amount of galaxies in the universe.
I find it really sweet that the author of the article illustrates the perspective of our place in the universe as her father is known for just the same rhing :D
I've had a framed poster of the Hubble Deep Field on my wall since the late 90s. I see it every day when I wake up. It's the only wall-art I own that I know I'll never swap out for something else.
Paywall links need to be downvoted
It’s amazing we have a giant telescope outside the planet. We know so much about the universe because of Hubble and friends.
When I was young I truly believed in heaven and hell as some distant planets. Then learning about Hubble, cosmic radiation and the fact that we can see millions of lightyears away which is an incomprehensible distance and the fact that our vision is limited by speed of light that seems super slow relative to those distances.
I really had a paradigm shift. Heaven and hell are probably good ideas but don’t actually physically exist. Took me a while to digest that. If they were actually there, we’d have seen them by now.
I have a lot of respect for Astronomy.