DUNE scientists observe first neutrinos with prototype detector at Fermilab(newscenter.lbl.gov)
newscenter.lbl.gov
DUNE scientists observe first neutrinos with prototype detector at Fermilab
https://newscenter.lbl.gov/2024/08/12/dune-scientists-observe-first-neutrinos-with-prototype-detector-at-fermilab/
132 comments
Fascinating. But I (non-physics person) don’t understand how the neutrinos won’t interact with atoms in the earth’s crust and their trajectory be deviated in the long journey between the 2 sites.
For typical solar neutrino energies, and given Fermilab and South Dakota are about 750 miles apart, around one in 10^15 neutrinos would interact with the ground (more specifically, the nucleus of an atom in the ground).
It would take about 10^14 miles (17 light years) of solid lead to block 50% of neutrinos.
Imagine that you are a tiny, tiny, tiny neutrino. You are a million times smaller than an electron. You are drifting through space, and the only other component of space that you can interact with is the nucleus of atoms. But atoms also have electron shells that repel each other, so the nuclei have to be centered inside electron clouds that refuse to go anywhere near each other. The nucleus of each atom is only 1/25,000 the width of the electron cloud, or the "full width" of the atom.
In other words, travelling through solid lead, for neutrinos, is like flying through mostly empty space.
From the perspective of a neutrino, in solid lead, if each lead atom was centered on a star in the Milky Way galaxy, each lead nucleus would be the diameter of Jupiter's orbit. Everything else would be pure emptiness.
Continuing with this blown-up scale, you would need to fly your spaceship for 10^27 lightyears before you have a 50% chance of flying within the Jupiter orbit distance of a star.
The universe is only 10^11 light years wide, so you would need to fly through 10^16 universes before you have a 50% chance of passing within the Jupiter orbit of a star. And this is assuming the entire universe is as dense as the milky way's disk around us.
It would take about 10^14 miles (17 light years) of solid lead to block 50% of neutrinos.
Imagine that you are a tiny, tiny, tiny neutrino. You are a million times smaller than an electron. You are drifting through space, and the only other component of space that you can interact with is the nucleus of atoms. But atoms also have electron shells that repel each other, so the nuclei have to be centered inside electron clouds that refuse to go anywhere near each other. The nucleus of each atom is only 1/25,000 the width of the electron cloud, or the "full width" of the atom.
In other words, travelling through solid lead, for neutrinos, is like flying through mostly empty space.
From the perspective of a neutrino, in solid lead, if each lead atom was centered on a star in the Milky Way galaxy, each lead nucleus would be the diameter of Jupiter's orbit. Everything else would be pure emptiness.
Continuing with this blown-up scale, you would need to fly your spaceship for 10^27 lightyears before you have a 50% chance of flying within the Jupiter orbit distance of a star.
The universe is only 10^11 light years wide, so you would need to fly through 10^16 universes before you have a 50% chance of passing within the Jupiter orbit of a star. And this is assuming the entire universe is as dense as the milky way's disk around us.
Addendum: 1,000km of neutron star material would block 50% of solar energy neutrinos.
Unfortunately, a neutron star larger than 22km diameter collapses into a black hole.
Unfortunately, a neutron star larger than 22km diameter collapses into a black hole.
Lovely explanation! Thank you! It is simultaneously crazy that neutrinos can pass through so much matter unhindered, yet intuitive that when something is so small and can only interact with such a small fraction of the volume it is passing through - it can indeed pass unhindered.
It's a big part of what makes them hard to detect. They interact with almost nothing. (source: i'm not a physics person either, but i watch a lot of physics videos)
I believe they might, but it's all a question of how large or small the probability is. And in the case of neutrinos, my lay-person understanding is that the probability of interaction is incredibly small.
Anytime I hear about neutrino-related numbers my mind is blown. I have a hard time truly wrapping my head around these numbers... for eg.: "At the surface of the Earth, the flux is about 65 billion (6.5 × 10^10) solar neutrinos, per second per square centimeter." (wiki intro)
Anytime I hear about neutrino-related numbers my mind is blown. I have a hard time truly wrapping my head around these numbers... for eg.: "At the surface of the Earth, the flux is about 65 billion (6.5 × 10^10) solar neutrinos, per second per square centimeter." (wiki intro)
How far away is the far detector?
Fascinating that there's a neutrino beam cutting straight through the earth, in a chord hundreds of miles long, and they expect to be able to measure dozens of events per second (edit: at the closer of the two detectors—not the 800 mile one). If they were to modulate this beam, they could tweet-by-neutrino in near real-time.
- "DUNE is split between two locations hundreds of miles apart: A beam of neutrinos originating at Fermilab, close to Chicago, will pass through a particle detector located on the Fermilab site, then travel 800 miles through the ground to several huge detectors at the Sanford Underground Research Facility (SURF) in South Dakota."
- "The DUNE detector at Fermilab will analyze the neutrino beam close to its origin, where the beam is extremely intense. Collaborators expect this near detector to record about 50 interactions per pulse, which will come every second..."
- "DUNE is split between two locations hundreds of miles apart: A beam of neutrinos originating at Fermilab, close to Chicago, will pass through a particle detector located on the Fermilab site, then travel 800 miles through the ground to several huge detectors at the Sanford Underground Research Facility (SURF) in South Dakota."
- "The DUNE detector at Fermilab will analyze the neutrino beam close to its origin, where the beam is extremely intense. Collaborators expect this near detector to record about 50 interactions per pulse, which will come every second..."
> they could tweet-by-neutrino in near real-time
We demonstrated in 2012 a neutrino-based link which “achieved a decoded data rate of 0.1 bits/sec with a bit error rate of 1% over a distance of 1.035 km, including 240 m of earth” [1].
To put that into perspective, a through-the-core beam would reach its antipode about 24 milliseconds before its circumnavigating partner [2].
[1] https://arxiv.org/abs/1203.2847
[2] assuming a spherical earth with diameter 12 756 km [a] and circumference 40,075 km [b], and thus distance difference of 7 282 km, and a speed of light of 300mm m/s
[a] https://imagine.gsfc.nasa.gov/features/cosmic/earth_info.htm...
[b] https://en.wikipedia.org/wiki/Earth%27s_circumference
We demonstrated in 2012 a neutrino-based link which “achieved a decoded data rate of 0.1 bits/sec with a bit error rate of 1% over a distance of 1.035 km, including 240 m of earth” [1].
To put that into perspective, a through-the-core beam would reach its antipode about 24 milliseconds before its circumnavigating partner [2].
[1] https://arxiv.org/abs/1203.2847
[2] assuming a spherical earth with diameter 12 756 km [a] and circumference 40,075 km [b], and thus distance difference of 7 282 km, and a speed of light of 300mm m/s
[a] https://imagine.gsfc.nasa.gov/features/cosmic/earth_info.htm...
[b] https://en.wikipedia.org/wiki/Earth%27s_circumference
The relevant RFC is from (April 1st) 1991 - Memo from the Consortium for Slow Commotion Research (CSCR) https://www.rfc-editor.org/rfc/rfc1217.html
Section 4 deals with Jam-Resistant Underwater Communication
Section 4 deals with Jam-Resistant Underwater Communication
The ULS system proposed in (2) above has the weakness that it is
readily jammed by simple depth charge explosions or other sources of
acoustic noise (e.g., Analog Equipment Corporation DUCK-TALK voice
synthesizers linked with 3,000 AMP amplifiers). An alternative is to
make use of the ultimate in jam resistance: neutrino transmission.
For all practical purposes, almost nothing (including several light-
years of lead) will stop a neutrino. There is, however, a slight
cross-section which can be exploited provided that a cubic mile of
sea water is available for observing occasional neutrino-chlorine
interactions which produce a detectable photon burst. Thus, we have
the basis for a highly effective, extremely low speed communication
system for communicating with submarines.> make use of the ultimate in jam resistance: neutrino transmission. For all practical purposes, almost nothing (including several light-years of lead) will stop a neutrino
Signals aren't jammed by being blocked but overpowered. If you want to disrupt someone's neutrino comms, you don't start building lead walls. You flood their volume with neutrino noise. (I don't know how feasible that is to continuously do over a large volume.)
Signals aren't jammed by being blocked but overpowered. If you want to disrupt someone's neutrino comms, you don't start building lead walls. You flood their volume with neutrino noise. (I don't know how feasible that is to continuously do over a large volume.)
To jam, presumably you need to know precisely where the receivers are.
> To jam, presumably you need to know precisely where the receivers are
You need to know where you don't want functioning receivers.
You need to know where you don't want functioning receivers.
IANAP (I'm not a physicist)...
Can a neutrino detector estimate the direction from which a neutrino arrived?
I'm wondering if that could help discriminate signal vs. jamming.
Can a neutrino detector estimate the direction from which a neutrino arrived?
I'm wondering if that could help discriminate signal vs. jamming.
Some neutrino detectors can estimate direction, see
https://en.wikipedia.org/wiki/IceCube_Neutrino_Observatory
which should be able to spot a supernova in our galaxy easily.
https://en.wikipedia.org/wiki/IceCube_Neutrino_Observatory
which should be able to spot a supernova in our galaxy easily.
Got me curious if that's enough margin for HFT firms to invest...
24 ms is massive. 0.1 bps makes it tricky to make use of.
It's going to be a lot less than 24ms though because that's the antipode which is worst case for a around-the-globe signal. However, the antipode for probably every single stock market is likely somewhere uninhabited. It's still going to be a huge improvement of course but I'm sure there's encode/decode times to convert to/from an electrical signal. And presumably the 0.1 bps probably means it also takes a long time to receive a single packet (error correction & collecting enough signal in the first place). So we're probably a long ways away from it making sense for that use case.
1 ms would still be a big deal in HFT. The low bitrate pretty much kills it though (and yes, probably whatever lengthy processing is required to get a signal out of the particle soup).
The cord connecting Europe to Australia is almost exactly through the centre of the planet.
Also, the latency difference is a lot higher than 24ms because the current best route is via a circuitous fibre link. Light is slowed down in the glass of the fibre significantly (about 30 to 40%).
Also, the latency difference is a lot higher than 24ms because the current best route is via a circuitous fibre link. Light is slowed down in the glass of the fibre significantly (about 30 to 40%).
With any luck we might work out how to slow it down even more:
https://sf-encyclopedia.com/entry/slow_glass (1966)
Selling picture view windows that sat out in the scenery of Yellowstone for a few years and nano-glass-dust total surveillance are just a few of the exciting possibilities.
https://sf-encyclopedia.com/entry/slow_glass (1966)
Selling picture view windows that sat out in the scenery of Yellowstone for a few years and nano-glass-dust total surveillance are just a few of the exciting possibilities.
Aren't satellite-satellite laser links the new standard for latency-sensitive communication since it's point to point and avoids delays from refraction?
I'm not sure if they have true global connectivity yet, but. . . I'm sure SpaceX is working on it.
I'm not sure if they have true global connectivity yet, but. . . I'm sure SpaceX is working on it.
> cord connecting Europe to Australia
Also Puerto Rico to just off Australia.
Melbourne, the neutrino city!
Also Puerto Rico to just off Australia.
Melbourne, the neutrino city!
[deleted]
To be clear: 24 ms is a massive improvement you mean?
I assume yes considering much of HFT is measured in ns.
Transmit uncertainty by circumference ahead of time, and low bandwidth info that resolves uncertainty through the core?
Maybe they could use a large cluster of beams in parallel? :)
Most of those neutrinos will keep going though.
Imagine aliens come some day and ask us "What's with all the neutrinos?" :-)
They're either going to be very confused or understand it perfectly depending on how their society(ies) work.
Not to mention we'll have to listen to people complaining that they have a headache because of neutrinos..
Imagine aliens come some day and ask us "What's with all the neutrinos?" :-)
They're either going to be very confused or understand it perfectly depending on how their society(ies) work.
Not to mention we'll have to listen to people complaining that they have a headache because of neutrinos..
—I’ve become magnetized by the neutrinos! Look, my keys stick to my arm!
—Ma’m, that’s just because you’re sweaty and sweat makes your skin sticky.
—Ma’m, that’s just because you’re sweaty and sweat makes your skin sticky.
How soon until some high speed trader figures out this would be a faster way to send some data than sending it around the earth?
Kind of makes me want to hook a multi-mode decoding radio to the output of a high efficiency (lol) neutrino detector to see if any of those extrasolar neutrinos are just interstellar packet radio...
I'd like to imagine this as an early step towards omnidirectional point-to-point links blasting through the planet at each other to replace the need for switching/routing.
High frequency traders pay attention please.
> Fascinating that there's a neutrino beam cutting straight through the earth, in a chord hundreds of miles long
This is not the first time! Search about neutrinos from CERN to Gran Sasso.
This is not the first time! Search about neutrinos from CERN to Gran Sasso.
OPERA collaboration!
https://en.wikipedia.org/wiki/OPERA_experiment
https://en.wikipedia.org/wiki/OPERA_experiment
The K2K experiment also sent a beam from KEK to SuperK in Japan. I think there might have been one or two other exeriments like this. If you spend the time and money to create a neutrino detector, doing an experiment like this is a reasonable add on.
>a neutrino beam cutting straight through the earth, in a chord hundreds of miles long
In my copy of this mental image, I wondered if Earths' gravity, and indeed our movement through the cosmos, bends that chord, and what it would sound like ..
In my copy of this mental image, I wondered if Earths' gravity, and indeed our movement through the cosmos, bends that chord, and what it would sound like ..
Earth's gravity certainly does (though not by much); our movement through the cosmos shouldn't appreciably, since the Earth is in freefall. (But tides will affect it.)
The concept of near and far detector for a neutrinos experiment is not new. We already have NOvA which DUNE will be its successor and probably will be able to solve the neutrinos mass hierarchy by then.
[deleted]
Is there any current or potential overlap with gravity wave science like LIGO?
The article touches on black holes and supernovae. I am curious to learn more.
> It will enable scientists to explore new areas of neutrino research and possibly address some of the biggest physics mysteries in the universe, including searching for the origin of matter and learning more about supernovae and black hole formation.
The article touches on black holes and supernovae. I am curious to learn more.
> It will enable scientists to explore new areas of neutrino research and possibly address some of the biggest physics mysteries in the universe, including searching for the origin of matter and learning more about supernovae and black hole formation.
This is the dream of multi-messenger astronomy:
Simulations show that next generation gravitational wave detectors will be able to detect the initial part of the wave before the actual merger of objects (or collision?). If you can identify this signal in time, you could make the 'regular' telescopes look into that particular direction and look for a signal in light, and you could use a neutrino detector at the same time (think IceCube, KM3NeT, Baikal and others that look at large parts of the sky) to look in the neutrino channel.
This way you would have gravitational wave-, light- and neutrino-channels from a single object. This is still many years (decades?) away, but would be incredible for studying exotic objects.
If you mean, measuring the neutrino baseline difference when a GW passes through the Earth, perhaps. I never thought about it, but its definitely intriguing.
Simulations show that next generation gravitational wave detectors will be able to detect the initial part of the wave before the actual merger of objects (or collision?). If you can identify this signal in time, you could make the 'regular' telescopes look into that particular direction and look for a signal in light, and you could use a neutrino detector at the same time (think IceCube, KM3NeT, Baikal and others that look at large parts of the sky) to look in the neutrino channel.
This way you would have gravitational wave-, light- and neutrino-channels from a single object. This is still many years (decades?) away, but would be incredible for studying exotic objects.
If you mean, measuring the neutrino baseline difference when a GW passes through the Earth, perhaps. I never thought about it, but its definitely intriguing.
> If you mean, measuring the neutrino baseline difference when a GW passes through the Earth, perhaps. I never thought about it, but its definitely intriguing.
That's where my mind went. Lasers need a lot of precise controls for vibration and such, and neutrinos move through matter almost like it doesn't exist. If the emitter and detector were on opposite sides of the earth, and gravity effects the neutrinos since they have mass, would that increase the resolution of a gravity wave detection?
The multi-messenger concept is fascinating too. Seems like the volume of discover is going to keep increasing exponentially.
That's where my mind went. Lasers need a lot of precise controls for vibration and such, and neutrinos move through matter almost like it doesn't exist. If the emitter and detector were on opposite sides of the earth, and gravity effects the neutrinos since they have mass, would that increase the resolution of a gravity wave detection?
The multi-messenger concept is fascinating too. Seems like the volume of discover is going to keep increasing exponentially.
The main issue I foresee with this plan is getting a useful reading. We measure distances with photons by interfering them with a known reference. This raises a number of problems for neutrinos:
1. Neutrino reflection. LIGO and LISA use ultra precise mirrors. Can we build a neutrino mirror? Could we get away with something else instead, say sending beams around opposite sides of the Sun to combine them using gravitational lensing?
2. Neutrino interference. Is this a thing? Pretty sure it's not a thing.
3. Neutrino speed. Photons move at the speed of light. Neutrinos don't. Since we measure time and convert, we need a precise value for neutrino speed, which we currently lack.
1. Neutrino reflection. LIGO and LISA use ultra precise mirrors. Can we build a neutrino mirror? Could we get away with something else instead, say sending beams around opposite sides of the Sun to combine them using gravitational lensing?
2. Neutrino interference. Is this a thing? Pretty sure it's not a thing.
3. Neutrino speed. Photons move at the speed of light. Neutrinos don't. Since we measure time and convert, we need a precise value for neutrino speed, which we currently lack.
> 2. Neutrino interference. Is this a thing? Pretty sure it's not a thing.
It's an interesting question. I think that the answer is yes.
Assuming there are no experimental physicist nearby...
Trying to use a grating grid or mirrors with neutrinos is impossible, so you must try something else.
You must pick another particle that has charge and that decays to neutrinos, like in the article.
Yo must use a https://en.wikipedia.org/wiki/Stern%E2%80%93Gerlach_experime... to make two rays, the idea is that each particle is "split" in the two rays. (The correct formulation is more complicated and use a lot of algebra. The incorrect formulation say that each particle is split. Just bear with me and assume the particles can be split.)
If you miss align the two rays, perhaps with a magnetic field, you can get an interference pattern when the two parts of the particle colide when the ray colide (again, the algebra makes sense in spite the English version is weird).
But you can make the collision far away to ensure the particles have decayed and in the site of the collision they are neutrinos instead of the original particle. After the decay, the "two half" of the neutrinos are coherent and can produce an interference pattern.
So if you design everything very carefully, I think it's possible at least in theory.
I really don't expect that is humanly possible to build that experiment, but there are some ingenious people out there.
[What about aligning a supernova and two nearby black holes that act as gravitational lens. I'm not sure it works, but is sounds too cool not to try.]
It's an interesting question. I think that the answer is yes.
Assuming there are no experimental physicist nearby...
Trying to use a grating grid or mirrors with neutrinos is impossible, so you must try something else.
You must pick another particle that has charge and that decays to neutrinos, like in the article.
Yo must use a https://en.wikipedia.org/wiki/Stern%E2%80%93Gerlach_experime... to make two rays, the idea is that each particle is "split" in the two rays. (The correct formulation is more complicated and use a lot of algebra. The incorrect formulation say that each particle is split. Just bear with me and assume the particles can be split.)
If you miss align the two rays, perhaps with a magnetic field, you can get an interference pattern when the two parts of the particle colide when the ray colide (again, the algebra makes sense in spite the English version is weird).
But you can make the collision far away to ensure the particles have decayed and in the site of the collision they are neutrinos instead of the original particle. After the decay, the "two half" of the neutrinos are coherent and can produce an interference pattern.
So if you design everything very carefully, I think it's possible at least in theory.
I really don't expect that is humanly possible to build that experiment, but there are some ingenious people out there.
[What about aligning a supernova and two nearby black holes that act as gravitational lens. I'm not sure it works, but is sounds too cool not to try.]
I was just thinking about the distances used: in LIGO/VIRGO, the sizes of the chambers is 4 km, and the interferometric distance they look for is 10^{-18} m to detect a GW.
For the baseline of DUNE we have 1300km, so that would mean 10^{-15} m if we do a very simple comparison. (I am not that familiar with GW detection!).
Measuring neutrino events at such a resolution would seems not realistic currently, as most detector measure events at sizes of cm (reactor experiments)- to meters (atmospheric / galactic). However, don't discount someone coming up with a brilliant insight to actually do this measurement. Some things we measure today were thought impossible not that long ago, like GWs and the Event Horizon black hole image.
For the baseline of DUNE we have 1300km, so that would mean 10^{-15} m if we do a very simple comparison. (I am not that familiar with GW detection!).
Measuring neutrino events at such a resolution would seems not realistic currently, as most detector measure events at sizes of cm (reactor experiments)- to meters (atmospheric / galactic). However, don't discount someone coming up with a brilliant insight to actually do this measurement. Some things we measure today were thought impossible not that long ago, like GWs and the Event Horizon black hole image.
Non-physicist question:
What purpose do neutrinos serve in the complex world of elementary particles?
Are they "just" a side effect of radioactive decay, or do they facilitate some other reaction?
(edited to change the original question from "what are neutrinos for?" to the current question which was suggested by a grandchild comment)
What purpose do neutrinos serve in the complex world of elementary particles?
Are they "just" a side effect of radioactive decay, or do they facilitate some other reaction?
(edited to change the original question from "what are neutrinos for?" to the current question which was suggested by a grandchild comment)
Neutrinos were originally a kind of mathematical placeholder to allow for conservation of lepton number (electrons, muons, etc). Turns out that they're real! More to the point, you have six basic leptons (and their antiparticles) if you count the types of neutrinos and six basic quarks (and their antiparticles). It's an interesting parallel.
They react with very little, as it turns out. Chargeless, and so they care not for electromagnetic forces. Strong nuclear force is also a miss. Originally, it was thought that only the weak nuclear force was the way they could interact with matter, but with confirmation that they have a non-zero mass, they can also interact with gravity. This makes them both hard to detect, but also an excellent way to peer through things like clouds of interstellar dust, or through the Earth.
They react with very little, as it turns out. Chargeless, and so they care not for electromagnetic forces. Strong nuclear force is also a miss. Originally, it was thought that only the weak nuclear force was the way they could interact with matter, but with confirmation that they have a non-zero mass, they can also interact with gravity. This makes them both hard to detect, but also an excellent way to peer through things like clouds of interstellar dust, or through the Earth.
Even zero mass particles interact with gravity. Anything with energy does.
Having non zero mass means that at least in theory we could slow them down to get a better look at them. But so far we have no idea how, which means that we don't even know what the mass actually is. We just know from the way from the types of neutrinos observed that they can change type, and they couldn't do that if their mass were zero.
Having non zero mass means that at least in theory we could slow them down to get a better look at them. But so far we have no idea how, which means that we don't even know what the mass actually is. We just know from the way from the types of neutrinos observed that they can change type, and they couldn't do that if their mass were zero.
> Having non zero mass means that at least in theory we could slow them down to get a better look at them. But so far we have no idea how...
How about cosmic expansion? Of the neutrinos emitted early in the universe, shouldn't most still be around, given how weakly neutrinos interact? And, given how much everything in the early universe is receding from us, shouldn't they be slowed down in our frame of reference? If they were emitted when the universe became transparent to neutrinos, what Z would that correspond to? What velocity would we observe in the local frame of reference? (Does it depend on how close to c their velocity is? Do we know?)
What would we expect the density of such neutrinos to be? Enough that we could observe it? (One "gotcha" is that slower-moving neutrinos might have a smaller interaction profile than fast-moving ones, and so be harder to detect.)
Wikipedia says decoupling was at 1 second after the Big Bang, and that neutrinos from that era have energy of 1e-4 to 1e-6 eV (compared to current neutrinos that may be as much as 0.8 eV).
How about cosmic expansion? Of the neutrinos emitted early in the universe, shouldn't most still be around, given how weakly neutrinos interact? And, given how much everything in the early universe is receding from us, shouldn't they be slowed down in our frame of reference? If they were emitted when the universe became transparent to neutrinos, what Z would that correspond to? What velocity would we observe in the local frame of reference? (Does it depend on how close to c their velocity is? Do we know?)
What would we expect the density of such neutrinos to be? Enough that we could observe it? (One "gotcha" is that slower-moving neutrinos might have a smaller interaction profile than fast-moving ones, and so be harder to detect.)
Wikipedia says decoupling was at 1 second after the Big Bang, and that neutrinos from that era have energy of 1e-4 to 1e-6 eV (compared to current neutrinos that may be as much as 0.8 eV).
I don't know any answers here, but this is an awesome question. I too am now super-curious about the Cosmic Neutrino Background.
https://en.wikipedia.org/wiki/Cosmic_neutrino_background
...And I suppose there are probably good reasons for this to be impossible, but wouldn't it be wild if a "mechanism" for things like the "randomness" of beta decay were that a really slow/low energy neutrino from the big bang interacts with a neutron, causing it to decay into a proton, and an electron, and the neutrino gets a boost in energy as well.
https://en.wikipedia.org/wiki/Cosmic_neutrino_background
...And I suppose there are probably good reasons for this to be impossible, but wouldn't it be wild if a "mechanism" for things like the "randomness" of beta decay were that a really slow/low energy neutrino from the big bang interacts with a neutron, causing it to decay into a proton, and an electron, and the neutrino gets a boost in energy as well.
Antineutrinos can cause inverse beta decay, so maybe neutrinos can cause inverse fusion?
Edit: apparently it just causes transmutation.
https://en.wikipedia.org/wiki/Homestake_experiment
Edit: apparently it just causes transmutation.
https://en.wikipedia.org/wiki/Homestake_experiment
There are various kinds of neutrino interactions:
https://www.vivaxsolutions.com/physics/feynman-diagrams.aspx
...(scroll down for the nice animated diagrams).
https://www.vivaxsolutions.com/physics/feynman-diagrams.aspx
...(scroll down for the nice animated diagrams).
Sorry, I was being brief. I usually say "anything with a non-zero rest mass-energy" for anything for a photon, photons never being at rest. Briefly, some had thought that neutrinos might be little more than floating carriers of lepton number. Later that was amended to merely "massless" (in the sense that they would at least be like photons). I've never been in that crowd. My thoughts are that mass-energy is the coin of existence and gravitation the inevitable consequence, but I do not speak for everyone, just trying to give a kind of non-exhaustive overview of the history to respond to the for part.
Neutrino detectors essentially slow them down - a neutrino hits an electron, transferring momentum, and then the high speed electron gives off Cherenkov radiation.
Oversimplifiying, they are chargeless electrons.
If you have an electron(negative) and a proton (positive), then the charge may jump and you get a neutrino(no charge) and a neutron(no charge).
It's more common in the other direction. If ypu have a neutron(no charge) it splits into a proton(positive), an electron(negative) an an antineutrino(no charge).
If you have an electron(negative) and a proton (positive), then the charge may jump and you get a neutrino(no charge) and a neutron(no charge).
It's more common in the other direction. If ypu have a neutron(no charge) it splits into a proton(positive), an electron(negative) an an antineutrino(no charge).
Neutrinos must exist to satisfy conservation of lepton number. Specifically, the weak interaction can change flavor. In beta decay (for example), a down quark changes into an up quark, which converts a neutron into a proton and emits an electron. Conservation of lepton number implies that another particle must also be emitted with the properties of a neutrino.
They preserve the spin quantity in particle interactions. E.g. in beta decay a spin-neutral atom has a neutron that decays into a proton and an electron. Neutrons, protons and electrons have spin 1/2, so an extra 1/2 spin came about. An anti-neutrino has spin -1/2 which is emitted to balance the spin quantity.
- "do they facilitate some other reaction?"
They are not carriers of a fundamental force, if that's what you are thinking about.
https://en.wikipedia.org/wiki/Force_carrier
They are not carriers of a fundamental force, if that's what you are thinking about.
https://en.wikipedia.org/wiki/Force_carrier
Neutrinos can interact with atoms, producing high-energy charged particles.
They serve the same purpose as every particle field, a store of energy as it moves between forms in this waterfall of existence towards maximum entropy.
Do they have purpose to us / our technology?
Possibly the military can use them to communicate with submarines.
> What purpose do neutrinos serve in the complex world of elementary particles?
To utterly confuse physicists, no other purpose detected
To utterly confuse physicists, no other purpose detected
pfdietz(3)
> what are neutrinos for?
I'm not sure I understand your question, sorry!
> Are they "just" a side effect of radioactive decay
They are (as fas as we know) elementary particles as several other elementary particles.
> do they facilitate some other reaction?
Again, I'm not sure I get the sense of your question, but I'd say no, as they are the most elusive particles we know.
I'm not sure I understand your question, sorry!
> Are they "just" a side effect of radioactive decay
They are (as fas as we know) elementary particles as several other elementary particles.
> do they facilitate some other reaction?
Again, I'm not sure I get the sense of your question, but I'd say no, as they are the most elusive particles we know.
I'm far from an expert in this area, but as I understand it, neutrino and anti-neutrino detectors have some application in nuclear non-proliferation, as you can use them to identify the whereabouts of nuclear reactors, and maybe even fissile materials if your detector is close enough.
I wonder if this new neutrino detector has similar potential applications?
I wonder if this new neutrino detector has similar potential applications?
I'm not an expert, but that sounds unrealistic today considering how much difficulty we have making basic measurements of neutrinos.
It always struck me as weird that proponents of the Fermi paradox use lack of radio signals as indication we're alone. Ignoring that radio signals were audible from Earth for maybe 100 years before we significantly reduced the power associated (& switched to digital) and started encrypting everything (makes everything look like noise).
Once you start to consider neutrinos as a communication medium which we're just barely scratching the surface of, or whatever future technology might be possible with advances in science and engineering, then it becomes clear we don't know what to look for on the technological front for an advanced civilization (other than knowing it's unlikely to be 1950s analog radio waves).
Once you start to consider neutrinos as a communication medium which we're just barely scratching the surface of, or whatever future technology might be possible with advances in science and engineering, then it becomes clear we don't know what to look for on the technological front for an advanced civilization (other than knowing it's unlikely to be 1950s analog radio waves).
Lack of radio signals is a pretty tiny portion of the Fermi paradox. Fermi himself wasn't even thinking of them at the time according to the other Los Alamos scientists that were part of the conversation, but instead about having evidence of actual visitation. While the galaxy is mindbogglingly vast, even with the slower methods of interstellar travel that we could feasible achieve based on our current knowledge, we're talking about timeframes to traverse it that are not large on geological timescales, much less cosmological ones.
There's lots of interesting reasons to pay attention to radio signals beyond 'Aliens broadcasting TV, music, and talk radio' - lots of neat stuff has radio waves as a consequence - and since we're already listening in and interpreting that data, it's pretty cost effective for us to also look for it in a technosignature context.
But there's a reasonably wide variety of other technosignatures we actively look for today, and others that scientists attempt to infer out of data gathered for other reasons.
Also, the whole way you've phrased your comment is kind of strange. The Fermi paradox doesn't advocate the idea that we're alone - it's about the discrepancy between how ubiquitous intelligence life should be in the universe at large based on our understandings of how life came into existence and how little evidence we have that that is the case. "We weren't looking at/for the right things" would 100% be a reasonable answer to the paradox that the overwhelming majority of scientists in the related fields would take no issue with if we suddenly discovered alien life through some different technosignature than we currently look for. Something like a dyson sphere or swarm would never have come into the conversation when Fermi first proposed the question (and he wasn't the first person to ask where everybody was, either) but are now seen as plausible enough that respected scientists in the field pour over things like the Kepler data looking for evidence of them.
The Fermi paradox doesn't really need "proponents" - as long as we have no evidence of intelligent life or our understandings of how common intelligent life should be in the universe change, the paradox will stand. But I don't think there's any real faction of people that want it to stand, though. Every scientist or enthusiast on the subject I've ever spoken to or read thoughts on the subject would love to have an answer to the paradox.
There's lots of interesting reasons to pay attention to radio signals beyond 'Aliens broadcasting TV, music, and talk radio' - lots of neat stuff has radio waves as a consequence - and since we're already listening in and interpreting that data, it's pretty cost effective for us to also look for it in a technosignature context.
But there's a reasonably wide variety of other technosignatures we actively look for today, and others that scientists attempt to infer out of data gathered for other reasons.
Also, the whole way you've phrased your comment is kind of strange. The Fermi paradox doesn't advocate the idea that we're alone - it's about the discrepancy between how ubiquitous intelligence life should be in the universe at large based on our understandings of how life came into existence and how little evidence we have that that is the case. "We weren't looking at/for the right things" would 100% be a reasonable answer to the paradox that the overwhelming majority of scientists in the related fields would take no issue with if we suddenly discovered alien life through some different technosignature than we currently look for. Something like a dyson sphere or swarm would never have come into the conversation when Fermi first proposed the question (and he wasn't the first person to ask where everybody was, either) but are now seen as plausible enough that respected scientists in the field pour over things like the Kepler data looking for evidence of them.
The Fermi paradox doesn't really need "proponents" - as long as we have no evidence of intelligent life or our understandings of how common intelligent life should be in the universe change, the paradox will stand. But I don't think there's any real faction of people that want it to stand, though. Every scientist or enthusiast on the subject I've ever spoken to or read thoughts on the subject would love to have an answer to the paradox.
If the probability works out to 1 intelligent civilization per galaxy on average, then we wouldn't expect any other civilizations in our neck of the woods to discover (i.e. we could be the first or at least the only currently active one in our galaxy).
If the probability works out to a few per galaxy, we don't actually know that it's possible for a civilization to practically leave their own solar system. Or it could be that in the amount of time since the Big Bang, we'd be the only ones that have had time to develop in our galaxy since the Big Bang. Or we could be the only ones to have developed in our neck of the woods for distances that aren't horribly relativistic (e.g. our furthest telescopes are looking back billions of years so who knows the current state of those places).
As for the assumption that the galaxy would be teeming with life, it's not even clear that we can ever get to Alpha Centauri in a reasonable time frame. 80 years would require an average 5% the speed of light to get there (meaning much faster peak to do accelerate halfway / decelerate halfway). That's a lot of fuel so it's a huge stretch to claim we have that technology today. A 1% speed of life average speed would be a 400 year one-way trip. And even if we do build technology capable of this and go there, does that mean that Alpha Centauri then has the resources needed to bootstrap & proceed to the next star system or does it take a long time to build up a manufacturing base in the local star system to continue on the journey (i.e. you may be able to get to 1% the speed of light to travel between systems but traveling between planets within a system might still take a long time to collect resources & build out another space port)? In other words, how quickly do we go from star system to star system colonizing? There's no reason to believe that any intelligent civilization would be immune from economic pressures similar to humanity in terms of not taking on centennial or millennial interstellar projects. And as we can tell from humans on earth, there are economic, resource, technological, & timing reasons why we don't just start firing probes out into other star systems to try to do exploration.
We also don't know how long the universe needed to cool & coalesce for before life had the appropriate conditions to evolve; it's not like life existed from the first moment Earth formed. It likely needed to exist for billions of years after the solar system coalesced & then for billions of years it was still getting pummeled by asteroids & comets within the orbital plane until it got cleared out. After all, Mars seems to have been similar in many ways but ended up dead so it's clearly a knife's edge (e.g. Jupiter protecting us from a bunch of incoming asteroids and comets).
Finally, we have no idea whether intelligent civilizations have enough resources and survive long enough to leave their star system & to remain stable continuing to explore well beyond or collapse.
And all of that isn't even touching that our ability to look for these technosignatures is extremely limited because we don't know what we're looking for, we don't know where to look for it, & we are blindly guessing at the signatures we might find.
My point is - it's not a paradox unless you make some pretty wild assumptions that have no basis for them in the first place - we have no priors to inform probabilities to determine how many civilizations to look for. Nor do we even have search criteria for where to look. And we know that some pretty crazy technology that we have no way to detect is possible. As for visitation, I think people are way too optimistic about the ease with which such problems could be solved. & even if it does, we're at the outermost arm of the galaxy. Why would we be particularly interesting for aliens to visit? e.g. what star system would we pick to visit? Probably one with more resources that we've run out of rather than one with life if we've already convinced ourselves life is abundant in the universe & uninteresting to find.
If the probability works out to a few per galaxy, we don't actually know that it's possible for a civilization to practically leave their own solar system. Or it could be that in the amount of time since the Big Bang, we'd be the only ones that have had time to develop in our galaxy since the Big Bang. Or we could be the only ones to have developed in our neck of the woods for distances that aren't horribly relativistic (e.g. our furthest telescopes are looking back billions of years so who knows the current state of those places).
As for the assumption that the galaxy would be teeming with life, it's not even clear that we can ever get to Alpha Centauri in a reasonable time frame. 80 years would require an average 5% the speed of light to get there (meaning much faster peak to do accelerate halfway / decelerate halfway). That's a lot of fuel so it's a huge stretch to claim we have that technology today. A 1% speed of life average speed would be a 400 year one-way trip. And even if we do build technology capable of this and go there, does that mean that Alpha Centauri then has the resources needed to bootstrap & proceed to the next star system or does it take a long time to build up a manufacturing base in the local star system to continue on the journey (i.e. you may be able to get to 1% the speed of light to travel between systems but traveling between planets within a system might still take a long time to collect resources & build out another space port)? In other words, how quickly do we go from star system to star system colonizing? There's no reason to believe that any intelligent civilization would be immune from economic pressures similar to humanity in terms of not taking on centennial or millennial interstellar projects. And as we can tell from humans on earth, there are economic, resource, technological, & timing reasons why we don't just start firing probes out into other star systems to try to do exploration.
We also don't know how long the universe needed to cool & coalesce for before life had the appropriate conditions to evolve; it's not like life existed from the first moment Earth formed. It likely needed to exist for billions of years after the solar system coalesced & then for billions of years it was still getting pummeled by asteroids & comets within the orbital plane until it got cleared out. After all, Mars seems to have been similar in many ways but ended up dead so it's clearly a knife's edge (e.g. Jupiter protecting us from a bunch of incoming asteroids and comets).
Finally, we have no idea whether intelligent civilizations have enough resources and survive long enough to leave their star system & to remain stable continuing to explore well beyond or collapse.
And all of that isn't even touching that our ability to look for these technosignatures is extremely limited because we don't know what we're looking for, we don't know where to look for it, & we are blindly guessing at the signatures we might find.
My point is - it's not a paradox unless you make some pretty wild assumptions that have no basis for them in the first place - we have no priors to inform probabilities to determine how many civilizations to look for. Nor do we even have search criteria for where to look. And we know that some pretty crazy technology that we have no way to detect is possible. As for visitation, I think people are way too optimistic about the ease with which such problems could be solved. & even if it does, we're at the outermost arm of the galaxy. Why would we be particularly interesting for aliens to visit? e.g. what star system would we pick to visit? Probably one with more resources that we've run out of rather than one with life if we've already convinced ourselves life is abundant in the universe & uninteresting to find.
Everything you touch on is part of one or more potential answers to the Fermi paradox that have been proposed. And they're good points! One or all of them might be the answer.
> My point is - it's not a paradox unless you make some pretty wild assumptions that have no basis for them in the first place (i.e. no priors to inform probabilities or search criteria).
I think this is where there's a lot of talking past each other. All we have is our current understanding of things, and the paradox is simply going "Huh. Based on what we know, seems like there should be other intelligent life out there we'd have evidence of. Weird that isn't not there, right?" It's not really a matter of making wild assumptions, just going off of the evidence we have at current.
Fermi asked the question while eating lunch - it wasn't a theory he wrote. It's not based on a body of theory and work specific to it. There's not some huge amount of scientific rigor behind it stating intelligent aliens aren't out there. It's just a question of why haven't we seen it.
Most research on this subject is a byproduct of other research. There are very few scientists that would say their primary research is SETI - dozens to a hundred or so? And even some of the largest and best funded projects in this field like Breakthrough Listen generally don't have scientists working exclusively on it - it might be a significant portion of their time, but for most it is not their exclusive focus.
> My point is - it's not a paradox unless you make some pretty wild assumptions that have no basis for them in the first place (i.e. no priors to inform probabilities or search criteria).
I think this is where there's a lot of talking past each other. All we have is our current understanding of things, and the paradox is simply going "Huh. Based on what we know, seems like there should be other intelligent life out there we'd have evidence of. Weird that isn't not there, right?" It's not really a matter of making wild assumptions, just going off of the evidence we have at current.
Fermi asked the question while eating lunch - it wasn't a theory he wrote. It's not based on a body of theory and work specific to it. There's not some huge amount of scientific rigor behind it stating intelligent aliens aren't out there. It's just a question of why haven't we seen it.
Most research on this subject is a byproduct of other research. There are very few scientists that would say their primary research is SETI - dozens to a hundred or so? And even some of the largest and best funded projects in this field like Breakthrough Listen generally don't have scientists working exclusively on it - it might be a significant portion of their time, but for most it is not their exclusive focus.
> All we have is our current understanding of things, and the paradox is simply going
Actually based on what I’ve learned about it, the paradox is actually doing both things: it’s assuming over enough time scale our technology evolves rapidly enough to unlock new physics to traverse the universe we don’t have today while simultaneously being able to detect it using insanely primitive technology by comparison. It would be like asking someone to detect an atomic explosion in our solar system in 1930 - an explosion we’d likely not even notice today I suspect. There’s simply not enough understanding, we’re monitoring too little of the universe, and the equipment to do the monitoring is too primitive if technology really continues to advance at the pace posed by the Fermi paradox.
Basically the Fermi paradox says “after the invention of modern science and Industrial Revolution, within a couple of hundred of years we were flying, within 50 years we’d left orbit and within 20 years or so we’d reached a moon. So surely after a few hundred thousand years the society should be able to reach and have colonized huge swaths of the galaxy”. But that kind of advancement would be at odds with our ability to detect such signatures and what we’re doing today is hypothesizing crazy sci-fi ideas and looking for those signatures with insanely primitive tools that have poor resolution. Communication we have 0 chance of spotting (encryption + energy efficiency = noise). Dyson spheres are interesting to look for but it’ll be a while before some novel ideas for how to spot them pan out (and that’s assuming the clever ideas are correct about what the footprint would look like and that Dyson spheres would be needed for long distance travel vs wormholes).
However based on our current understanding of technology long distance travel is simply not possible - the Milky Way itself is 100k light years across. Even at 10% light speed that’s 1 million years to traverse the galaxy and ignores the challenges (surfing that kind of distance traveling at such speeds and avoiding all kinds of things flying through space). And visiting (let alone building major hubs) various star systems is going to take significantly more than that. If you can only manage 1% then that’s a 10 million year undertaking just to go from one end to another. It’s easy to imagine that visiting many star systems would take billions of years and that’s with technology we don’t know we can even build. And ignoring the practical challenges of going that fast, needing to survive, decelerating, and ignoring the economics of creating a craft that can undertake and last a 100k year journey at relativistic speeds.
And saying we don’t have scientists working on this actually proves my point that there’s no paradox - no one is really working on this problem using very poor sensors trying to think as creatively as they can with basically 0 knowledge (compared to a civilization many thousands of years older than us) for signals we don’t know how or where to look for. So of course we haven’t found anything.
Actually based on what I’ve learned about it, the paradox is actually doing both things: it’s assuming over enough time scale our technology evolves rapidly enough to unlock new physics to traverse the universe we don’t have today while simultaneously being able to detect it using insanely primitive technology by comparison. It would be like asking someone to detect an atomic explosion in our solar system in 1930 - an explosion we’d likely not even notice today I suspect. There’s simply not enough understanding, we’re monitoring too little of the universe, and the equipment to do the monitoring is too primitive if technology really continues to advance at the pace posed by the Fermi paradox.
Basically the Fermi paradox says “after the invention of modern science and Industrial Revolution, within a couple of hundred of years we were flying, within 50 years we’d left orbit and within 20 years or so we’d reached a moon. So surely after a few hundred thousand years the society should be able to reach and have colonized huge swaths of the galaxy”. But that kind of advancement would be at odds with our ability to detect such signatures and what we’re doing today is hypothesizing crazy sci-fi ideas and looking for those signatures with insanely primitive tools that have poor resolution. Communication we have 0 chance of spotting (encryption + energy efficiency = noise). Dyson spheres are interesting to look for but it’ll be a while before some novel ideas for how to spot them pan out (and that’s assuming the clever ideas are correct about what the footprint would look like and that Dyson spheres would be needed for long distance travel vs wormholes).
However based on our current understanding of technology long distance travel is simply not possible - the Milky Way itself is 100k light years across. Even at 10% light speed that’s 1 million years to traverse the galaxy and ignores the challenges (surfing that kind of distance traveling at such speeds and avoiding all kinds of things flying through space). And visiting (let alone building major hubs) various star systems is going to take significantly more than that. If you can only manage 1% then that’s a 10 million year undertaking just to go from one end to another. It’s easy to imagine that visiting many star systems would take billions of years and that’s with technology we don’t know we can even build. And ignoring the practical challenges of going that fast, needing to survive, decelerating, and ignoring the economics of creating a craft that can undertake and last a 100k year journey at relativistic speeds.
And saying we don’t have scientists working on this actually proves my point that there’s no paradox - no one is really working on this problem using very poor sensors trying to think as creatively as they can with basically 0 knowledge (compared to a civilization many thousands of years older than us) for signals we don’t know how or where to look for. So of course we haven’t found anything.
Your entire post here is making a lot of incorrect assumptions about the paradox. As the other guy said, it's not some rigorous thing, but you're definitely not the first guy to think "Well... what if FTL travel isn't possible?" or "What if every single technological species in the entire universe all decided to hide their messages since their inception somehow?".
A million years in a cosmological timescale is nothing. The Earth is 4.5 billion years old, and we only came in right at the end. If we'd come in 200 Million years earlier, we'd have covered many, many galaxies by now - we could expand in all directions pretty much simultaneously.
This doesn't even begin to get into your assumption that every species in the universe would even WANT to hide - the concept of "territory" isn't exactly foreign to us. We don't need to prove that there IS a species acting this way to solve the paradox, we need to explain why NO species is doing this, or if they are, why NONE are putting up markers in a manner that's easy for everyone to see?
A million years in a cosmological timescale is nothing. The Earth is 4.5 billion years old, and we only came in right at the end. If we'd come in 200 Million years earlier, we'd have covered many, many galaxies by now - we could expand in all directions pretty much simultaneously.
This doesn't even begin to get into your assumption that every species in the universe would even WANT to hide - the concept of "territory" isn't exactly foreign to us. We don't need to prove that there IS a species acting this way to solve the paradox, we need to explain why NO species is doing this, or if they are, why NONE are putting up markers in a manner that's easy for everyone to see?
I never said it's a rigorous thing; I'm highlighting that there's too many flaws to take seriously (i.e. evidence of absence in this case tells us nothing).
Remember - it's a million to do a straight shot across the universe at quite a large portion of the speed of light. In terms of colonization we're talking billions of years for an unknown fraction of the galaxy, but definitely not the entire thing. And much of the galaxy may not even be suited for colonization (e.g. presumably you still need some raw resources & have to be careful about where you go to to expand)
As for "hiding" I never said they want to hide. But you only need to look at the modern world to realize that digital communication and encryption are standard fare and "hiding" is a natural evolution of that. And the longer distances you are transmitting and the more signals you need to monitor, the more energy efficient you want to be (i.e. point to point + relays instead of broadspectrum broadcasts). And if advanced civilizations use neutrino comms or quantum entaglement somehow, then they'd naturally be hidden just because that's how more advanced tech would work.
As for territory, I never said they wouldn't be territorial. But a lion isn't going to bother being territorial with a mouse. No reason to believe they're going to try to broadcast ownership in a way that a "stone age" species like ours could detect. Additionally, it's not impossible that communication barriers are real and therefore there's not really much to communicate out vs "show up in our heavily fortified star system & see disappear" kind of behavior.
The counter argument is that you may actually want to hide unless you're the apex civilization because otherwise the apex civilization may choose to conquer and murder yours (e.g. Europeans vs Native Americans) to prevent competition.
My point is that there's so many reasons that we're not finding anything (nonexistent priors, searching in the wrong spot, search for the wrong signals, not having enough people searching, having the wrong equipment, not even having the physics required to start searching, etc etc) that the Fermi paradox provides no insight & can't even be called a paradox yet.
If faster than light travel is possible, this changes a lot of calculus of course. But similarly, is there any reason to believe our solar system would be interesting enough for the species to come to us? Or maybe there's even political things like Star Trek's first contact rule that put us in a bubble & intentionally mask the existence of the aliens in the first place.
Remember - it's a million to do a straight shot across the universe at quite a large portion of the speed of light. In terms of colonization we're talking billions of years for an unknown fraction of the galaxy, but definitely not the entire thing. And much of the galaxy may not even be suited for colonization (e.g. presumably you still need some raw resources & have to be careful about where you go to to expand)
As for "hiding" I never said they want to hide. But you only need to look at the modern world to realize that digital communication and encryption are standard fare and "hiding" is a natural evolution of that. And the longer distances you are transmitting and the more signals you need to monitor, the more energy efficient you want to be (i.e. point to point + relays instead of broadspectrum broadcasts). And if advanced civilizations use neutrino comms or quantum entaglement somehow, then they'd naturally be hidden just because that's how more advanced tech would work.
As for territory, I never said they wouldn't be territorial. But a lion isn't going to bother being territorial with a mouse. No reason to believe they're going to try to broadcast ownership in a way that a "stone age" species like ours could detect. Additionally, it's not impossible that communication barriers are real and therefore there's not really much to communicate out vs "show up in our heavily fortified star system & see disappear" kind of behavior.
The counter argument is that you may actually want to hide unless you're the apex civilization because otherwise the apex civilization may choose to conquer and murder yours (e.g. Europeans vs Native Americans) to prevent competition.
My point is that there's so many reasons that we're not finding anything (nonexistent priors, searching in the wrong spot, search for the wrong signals, not having enough people searching, having the wrong equipment, not even having the physics required to start searching, etc etc) that the Fermi paradox provides no insight & can't even be called a paradox yet.
If faster than light travel is possible, this changes a lot of calculus of course. But similarly, is there any reason to believe our solar system would be interesting enough for the species to come to us? Or maybe there's even political things like Star Trek's first contact rule that put us in a bubble & intentionally mask the existence of the aliens in the first place.
Your statements are framed as arguments, like in a debate. But it’s clear to most, at least clear to the down voters and the other responders, that you haven’t thought about or investigated these concepts. Instead of writing many argumentative paragraphs, spend that time asking ChatGPT specific questions or skimming some Wikipedia articles. Some people don’t like to read, they’d rather explore ideas by arguing about them. But that’s a drain on discussions, not an addition to it.
E.g.(paraphrased) “my point is the Fermi paradox is dumb”- no physicists think that is the case. Some people on the outside, looking in, with no understanding think so. A child walks into a theatre halfway through a movie that is geared towards adults, watches for 3 minutes, and announces defiantly that the movie is dumb. Is it worth arguing with that child?
E.g.(paraphrased) “my point is the Fermi paradox is dumb”- no physicists think that is the case. Some people on the outside, looking in, with no understanding think so. A child walks into a theatre halfway through a movie that is geared towards adults, watches for 3 minutes, and announces defiantly that the movie is dumb. Is it worth arguing with that child?
It’s good as a thought experiment to think through why we don’t see signals, but that’s about it. The Wikipedia page lists plenty of reasonable hypotheses to explain. Heck, even the explanation of the paradox itself indicates a huge problem in the radio transmissions search:
> The most sensitive radio telescopes on Earth, as of 2019, would not be able to detect non-directional radio signals (such as broadband) even at a fraction of a light-year away,[49] but other civilizations could hypothetically have much better equipment.
So we don’t even have equipment that could detect equivalent passive signals from our planet in the nearest other solar system. And our planet is increasingly not emitting loud broadband signals instead preferring fiber optics and point to point links for bandwidth and efficiency reasons (+ encryption).
I have yet to find anyone who believes that the Fermi paradox is real who bothers to offer a justification that doesn’t rely on assumptions about FTL or completely ignore the practical challenges of we’re not even seriously looking and don’t really know what to look for let alone the serious practical challenges that interstellar travel could be a huge barrier since we don’t even have a counter that such travel is indeed possible (eg even our furthest probe which required a confluence of orbital mechanics to make that speed possible in the first place would need to travel ~500x longer just to reach the nearest solar system).
I’m glad insulting me makes you feel good but pointing me at convincing counter arguments to theist basic practical counter arguments might be a better use of time if you found any that are so obviously compelling.
> The most sensitive radio telescopes on Earth, as of 2019, would not be able to detect non-directional radio signals (such as broadband) even at a fraction of a light-year away,[49] but other civilizations could hypothetically have much better equipment.
So we don’t even have equipment that could detect equivalent passive signals from our planet in the nearest other solar system. And our planet is increasingly not emitting loud broadband signals instead preferring fiber optics and point to point links for bandwidth and efficiency reasons (+ encryption).
I have yet to find anyone who believes that the Fermi paradox is real who bothers to offer a justification that doesn’t rely on assumptions about FTL or completely ignore the practical challenges of we’re not even seriously looking and don’t really know what to look for let alone the serious practical challenges that interstellar travel could be a huge barrier since we don’t even have a counter that such travel is indeed possible (eg even our furthest probe which required a confluence of orbital mechanics to make that speed possible in the first place would need to travel ~500x longer just to reach the nearest solar system).
I’m glad insulting me makes you feel good but pointing me at convincing counter arguments to theist basic practical counter arguments might be a better use of time if you found any that are so obviously compelling.
“It’s only good as a thought experiment”. Framed as an argument. Did you notice you’ve switched sides? The Theseus ship paradox has at least 2 perfectly good answers, Is it dumb?
Another responder already gave you what you’re asking for: billion year timescales. You countered “500x”. Did you multiply 500 times x (47) and compare that to a billion? You latched onto that idea eagerly because it supported “your side”, but I’m sure once you think about it you’ll see it’s only a tiny fraction of a real counter argument.
You mistake me for an opponent. Me insulting you would look different. You’re the only one that can benefit from these comments I’m making to you.
Another responder already gave you what you’re asking for: billion year timescales. You countered “500x”. Did you multiply 500 times x (47) and compare that to a billion? You latched onto that idea eagerly because it supported “your side”, but I’m sure once you think about it you’ll see it’s only a tiny fraction of a real counter argument.
You mistake me for an opponent. Me insulting you would look different. You’re the only one that can benefit from these comments I’m making to you.
> So we don’t even have equipment that could detect equivalent passive signals from our planet in the nearest other solar system. And our planet is increasingly not emitting loud broadband signals instead preferring fiber optics and point to point links for bandwidth and efficiency reasons (+ encryption).
Sure. Which is why no one particularly expects broadband radio signals to be the first indication we find of other intelligent life out there. Narrowband signals, particularly pulsed ones, are one of the (relatively) more likely indicators, but these are still very much a "We are doing radio astronomy already and the same sort of weirdness we would expect from intelligent life is already the sort of weirdness we're looking for for a variety of other reasons, so doing a bit more to differentiate between that and other phenomena is cheap. Pulsars are a good example here - pulsars are cool and we get excited when we find new ones, but they're the sort of oddity that could be quite similar to what we would see from intelligent life.
Radio gets a lot of discussion here for a couple of reasons - the first being that we can just look at a whole lot of it, for the previously mentioned reasons, but also because it plays a bit into the whole human tendency to get excited about things that make them a little afraid. WE'VE been broadcasting out to the universe so people imagine a bit what might happen if someone out there is listening. There's the whole Dark Forest hypothesis, so maybe we've signed our own death warrant by leaking these radio waves! Probably not, but it can be entertaining to talk about, so people do.
But in general, most scientists really only expect to learn of intelligent life via radio transmissions if someone is specifically attempting to talk to us, regardless of whether or not life is ubiquitous in the galaxy or universe at large.
> I have yet to find anyone who believes that the Fermi paradox is real who bothers to offer a justification that doesn’t rely on assumptions about FTL or completely ignore the practical challenges of we’re not even seriously looking and don’t really know what to look for let alone the serious practical challenges that interstellar travel could be a huge barrier since we don’t even have a counter that such travel is indeed possible (eg even our furthest probe which required a confluence of orbital mechanics to make that speed possible in the first place would need to travel ~500x longer just to reach the nearest solar system).
Again, "believers" in the fermi paradox (this is still a REALLY WEIRD way to frame the discussion! people don't talk about it in this manner!) don't have some firm belief that there aren't aliens out there. They might suspect that we could be the only intelligent species in the galaxy but I've never seen or read of any scientist that talks about this subject going "nope no way intelligent life exists in our neighborhood we would 100% have seen it if it did!" - and this is a subject I find interesting so I've read a lot of writing and listened to a lot of talks on this subject.
But no one is ignoring the possibility of FTL or the idea that we might have no idea what to actually look for. Hell, maybe there's just no reason to expand to any significant portion of the galaxy - perhaps most civilizations focus on becoming hyper efficient in their resource utilization and only expand as absolutely necessary, or download their consciousnesses into a simulation, or whatever. But human nature has been to expand to everywhere we can, and humans are the only "advanced" intelligence we can go off of - so colonizing the galaxy seems like a reasonable thing to assume other species might do, based on our own experiences. And you don't need FTL or even travel that goes at a significant fraction of the speed of light to have colonized much of the galaxy on the timeframes we're talking. The Milky Way is 13.6 billion years old and we know of planets that formed quite early in the Milky Way's history. Now, we think that it would have been tough for anywhere in the galaxy to have been particularly habitable until 6 billion years ago or so, but Earth is about 4.5b years old - there's a whole lot of planets that would have had a 1.5b year head start to get to where we are now. 1.5 billion! Even at 1% the speed of light and not using anything like von neumann probes that's a lot of time to do a whole lot of colonizing. And we're pretty sure that our current understanding of technology could let us build something that reaches 8-10% the speed of light via nuclear pulse propulsion. Give us a hundred thousand years, much less a million, and we've not even scratched the surface of our time budget and we'd almost certainly have technology that would let us go even faster.
Sure. Which is why no one particularly expects broadband radio signals to be the first indication we find of other intelligent life out there. Narrowband signals, particularly pulsed ones, are one of the (relatively) more likely indicators, but these are still very much a "We are doing radio astronomy already and the same sort of weirdness we would expect from intelligent life is already the sort of weirdness we're looking for for a variety of other reasons, so doing a bit more to differentiate between that and other phenomena is cheap. Pulsars are a good example here - pulsars are cool and we get excited when we find new ones, but they're the sort of oddity that could be quite similar to what we would see from intelligent life.
Radio gets a lot of discussion here for a couple of reasons - the first being that we can just look at a whole lot of it, for the previously mentioned reasons, but also because it plays a bit into the whole human tendency to get excited about things that make them a little afraid. WE'VE been broadcasting out to the universe so people imagine a bit what might happen if someone out there is listening. There's the whole Dark Forest hypothesis, so maybe we've signed our own death warrant by leaking these radio waves! Probably not, but it can be entertaining to talk about, so people do.
But in general, most scientists really only expect to learn of intelligent life via radio transmissions if someone is specifically attempting to talk to us, regardless of whether or not life is ubiquitous in the galaxy or universe at large.
> I have yet to find anyone who believes that the Fermi paradox is real who bothers to offer a justification that doesn’t rely on assumptions about FTL or completely ignore the practical challenges of we’re not even seriously looking and don’t really know what to look for let alone the serious practical challenges that interstellar travel could be a huge barrier since we don’t even have a counter that such travel is indeed possible (eg even our furthest probe which required a confluence of orbital mechanics to make that speed possible in the first place would need to travel ~500x longer just to reach the nearest solar system).
Again, "believers" in the fermi paradox (this is still a REALLY WEIRD way to frame the discussion! people don't talk about it in this manner!) don't have some firm belief that there aren't aliens out there. They might suspect that we could be the only intelligent species in the galaxy but I've never seen or read of any scientist that talks about this subject going "nope no way intelligent life exists in our neighborhood we would 100% have seen it if it did!" - and this is a subject I find interesting so I've read a lot of writing and listened to a lot of talks on this subject.
But no one is ignoring the possibility of FTL or the idea that we might have no idea what to actually look for. Hell, maybe there's just no reason to expand to any significant portion of the galaxy - perhaps most civilizations focus on becoming hyper efficient in their resource utilization and only expand as absolutely necessary, or download their consciousnesses into a simulation, or whatever. But human nature has been to expand to everywhere we can, and humans are the only "advanced" intelligence we can go off of - so colonizing the galaxy seems like a reasonable thing to assume other species might do, based on our own experiences. And you don't need FTL or even travel that goes at a significant fraction of the speed of light to have colonized much of the galaxy on the timeframes we're talking. The Milky Way is 13.6 billion years old and we know of planets that formed quite early in the Milky Way's history. Now, we think that it would have been tough for anywhere in the galaxy to have been particularly habitable until 6 billion years ago or so, but Earth is about 4.5b years old - there's a whole lot of planets that would have had a 1.5b year head start to get to where we are now. 1.5 billion! Even at 1% the speed of light and not using anything like von neumann probes that's a lot of time to do a whole lot of colonizing. And we're pretty sure that our current understanding of technology could let us build something that reaches 8-10% the speed of light via nuclear pulse propulsion. Give us a hundred thousand years, much less a million, and we've not even scratched the surface of our time budget and we'd almost certainly have technology that would let us go even faster.
I have been watching Amazon and Alibaba for neutrino detectors. None so far.
How big is the experiment (outside distance)? It would be great to do a giant CAT scan of the Earth.
How big is the experiment (outside distance)? It would be great to do a giant CAT scan of the Earth.
Neutrinos don't really interact much with other matter so you need either a really intense source of neutrinos or a really big detector (think multiple tons of stuff ) or both. So you're talking about a 10m x 10m volume plus you need the detector to be in a place that doesn't get much other radiation so you need to bury it a few hundred meters underground.
So it’s gonna be a special order from Alibaba then?
Thirty thousand tons of liquid argon
A bit more than that.
>Combined, the four detector modules will hold nearly 70,000 tons of ultrapure liquid argon.
https://lbnf-dune.fnal.gov/how-it-works/detectors-and-comput...
>Combined, the four detector modules will hold nearly 70,000 tons of ultrapure liquid argon.
https://lbnf-dune.fnal.gov/how-it-works/detectors-and-comput...
And they did it all without House Atreides too
[stub for offtopicness. you're all correct, but it's fixed now]
Not Dune as in Arrakis, DUNE as in Deep Underground Neutrino Experiment
The SPICE must flow
(Small Particles Inside the Crust of the Earth)
(Small Particles Inside the Crust of the Earth)
Are you absolutely sure there is no Arrakis involved in the choosing of that acronym?
I firmly believe somebody is still giggling about the choice of acronym they managed to get approval for.
May their prototype detector never chip and shatter.
The title would be better if the original acronym capitalization was kept. "DUNE" not "Dune". I clicked through hoping to find out about a collaboration between geomorphologists and particle physicists. Still interesting but felt like a clickbait title.
Did the automatic headline mangler change "DUNE" the acronym for "Deep Underground Neutrino Experiment" to "Dune" the name of a heap of sand and also the nickname of a planet in a fictional universe?
Yes.
That's what it's been dune
So jealous they get to call themselves Dune scientists
I really hope someone on the team has Atreides as a last name.
This is super nerd interesting and everything, but does this have any real effect on everyday life?
I am very supportive of advancing science, but I just wonder if this is the top prioriy for spending in the current world...
I am very supportive of advancing science, but I just wonder if this is the top prioriy for spending in the current world...
Maybe one day, like faster communication through the planet. People were saying the same question you asked about radio waves only 100 years ago.
Sounds like research should start on it in another 100 years then...
Radio waves became "useful" because people continued studying them. Neutrinos becoming "useful" would require us continue to study them, not waiting an arbitrary amount of time to study them.
The study of neutrinos is important to our fundamental understanding of how the universe functions. By themselves they might not have some earth shattering ramifications for our day to day life (or they might!), but there's a lot of unanswered questions about how things work at a really fundamental level and neutrinos are among the things we have questions about. Answering these questions would have significant impact on basically every other more "macro" field of study.
The study of neutrinos is important to our fundamental understanding of how the universe functions. By themselves they might not have some earth shattering ramifications for our day to day life (or they might!), but there's a lot of unanswered questions about how things work at a really fundamental level and neutrinos are among the things we have questions about. Answering these questions would have significant impact on basically every other more "macro" field of study.
That just means the tech moves to 200 years away.
This is all from memory, but I remember the beamline setup was to get protons from the accelerator there, smash them into a target, which produced various charged particles which could be focused with the magnets, sent down a long pipe where they would decay into neutrinos et al. Then, there's a near detector and a far detector (far detector deep underground in South Dakota). The aim is to measure the neutrino flavors at both detectors to better understand the flavor oscillations (and look for asymmetries between neutrino/anti-neutrino oscillations, hopefully to help explain the matter/antimatter asymmetry in the universe).
The particular bit I worked most on was studying the effects of adding an additional solid absorber at the end of the beamline, which was needed to absorb all the particles that didn't decay in the pipe. It would produce more neutrinos that were unfocused, so would affect the near-far flavor statistics (since these would be detected at the near detector but not the far since they were unfocused, ruining the statistics). It was a great intro to doing physics research :-)