Scientists Propose Groundbreaking Method to Detect Single Gravitons
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Re: Scientists Propose Groundbreaking Method to Detect Single Gravitons
#2> Of course, there’s a catch with catching gravitons. The necessary sensing technology doesn’t quite yet exist.
That's, uh, kind of a big detail to not mention until the fourth paragraph from the bottom.
Re: Scientists Propose Groundbreaking Method to Detect Single Gravitons
#3> Of course, there’s a catch with catching gravitons. The necessary sensing technology doesn’t quite yet exist. That's, uh, kind of a big detail to not mention until the fourth paragraph from the bottom.
It's because there's no need to build it until you need to do this experiment though - this is the sort of bounds-pushing which top-end physics always does (i.e. before the LHC was built, sensors as good as ATLAS didn't exist, before LIGO the necessary interferometers didn't exist).
What they're proposing to build thought is however a logical refinement of established and demonstrated physical principles - it's entangling the vibrational state of a the big block of Aluminum to a system which you can more easily read out without disturbing it (examples in the literature seem to include circulating currents in super-conducting loops - so you can spectroscopically probe the state of the vibrating thing by looking at shifts in the emission/absorption of your superconductor, which is much easier).
Basically it is an experimental setup which is achievable with technology we would want to build anyway as a refinement of existing work.
Re: Scientists Propose Groundbreaking Method to Detect Single Gravitons
#4I haven't read this paper yet, but it does look interesting.
For context, there is a famous lecture by Freeman Dyson [1] in which he studies the question of whether it is possible in principle to detect an individual graviton. He considered a couple of different classes of detectors and his conclusions were mostly pessimistic. The essential problem with many detectors (e.g., something like LIGO) is that any detector that is sensitive enough to detect a single graviton would be so massive that it would collapse into a black hole.
I'll be curious to see how this new work fits into Dyson's framework.
[1]: http://publications.ias.edu/sites/default/files/poincare2012...
Re: Scientists Propose Groundbreaking Method to Detect Single Gravitons
#5This is cool... One of the team’s proposed innovations is to use available data from LIGO as a data/background filter...
“The LIGO observatories are very good at detecting gravitational waves, but they cannot catch single gravitons,” notes Beitel, a Stevens doctoral student. “But we can use their data to cross-correlate with our proposed detector to isolate single gravitons.”
Re: Scientists Propose Groundbreaking Method to Detect Single Gravitons
#6> Of course, there’s a catch with catching gravitons. The necessary sensing technology doesn’t quite yet exist. That's, uh, kind of a big detail to not mention until the fourth paragraph from the bottom.
It's easy to forget sometimes that the people taking it for granted that the technology doesn't exist yet are also the people whose work results in that technology being created. Of course it doesn't exist yet. Needing to invent better sensors, or better magnets, for the sake of running an experiment like this, is what causes those technologies to exist.
Re: Scientists Propose Groundbreaking Method to Detect Single Gravitons
#7In experiments that detect gravity waves, I recall the problem of Heisenberg Uncertainty Principle limiting our ability to see an individual graviton. I don't recall much detail and probably didn't understand fully when I read it. Something about our detectors and what an individual graviton effect would cause, falls within that limit; hence undetectable.
Does this change that theoretical limit?
Re: Scientists Propose Groundbreaking Method to Detect Single Gravitons
#8This is cool... One of the team’s proposed innovations is to use available data from LIGO as a data/background filter... “The LIGO observatories are very good at detecting gravitational waves, but they cannot catch single gravitons,” notes Beitel, a Stevens doctoral student. “But we can use their data to cross-correlate with our proposed detector to isolate single gravitons.”
Wasn't there a new way to measure gravitational waves; Ctrl-F hnlog for LIGO and LISA:
"Mass-Independent Scheme to Test the Quantumness of a Massive Object" (2024) https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.13... .. https://news.ycombinator.com/item?id=39048910 :
> This yields a striking result: a mass-independent violation of MR is possible for harmonic oscillator systems. In fact, our adaptation enables probing quantum violations for literally any mass, momentum, and frequency. Moreover, coarse-grained position measurements at an accuracy much worse than the standard quantum limit, as well as knowing the relevant parameters only to this precision, without requiring them to be tuned, suffice for our proposal. These should drastically simplify the experimental effort in testing the nonclassicality of massive objects ranging from atomic ions to macroscopic mirrors in LIGO.
From https://news.ycombinator.com/item?id=30847777 .. From "Massive Black Holes Shown to Act Like Quantum Particles" https://www.quantamagazine.org/massive-black-holes-shown-to-... :
> Physicists are using quantum math to understand what happens when black holes collide. In a surprise, they’ve shown that a single particle can describe a collision’s entire gravitational wave.
> "Scale invariance in quantum field theory" https://en.wikipedia.org/wiki/Scale_invariance#Scale_invaria...
"New ways to catch gravitational waves" https://news.ycombinator.com/item?id=40825994 :
- "Kerr-Enhanced Optical Spring" (2024) https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.13... .. "Kerr-enhanced optical spring for next-generation gravitational wave detectors" (2024) https://news.ycombinator.com/item?id=39957123
- "Physicists Have Figured Out a Way to Measure Gravity on a Quantum Scale" with a superconducting magnetic trap made out of Tantalum (2024) https://news.ycombinator.com/item?id=39495482
- "Measuring gravity with milligram levitated masses" (2024) https://www.science.org/doi/10.1126/sciadv.adk2949
"Physicists Have Figured Out a Way to Measure Gravity on a Quantum Scale" https://news.ycombinator.com/item?id=39495482#39495570 .. https://news.ycombinator.com/item?id=30847777 :
> Does a fishing lure bobber on the water produce gravitational waves as part of the n-body gravitational wave fluid field, and how separable are the source wave components with e.g. Quantum Fourier Transform/or and other methods?
Re: Scientists Propose Groundbreaking Method to Detect Single Gravitons
#9In experiments that detect gravity waves, I recall the problem of Heisenberg Uncertainty Principle limiting our ability to see an individual graviton. I don't recall much detail and probably didn't understand fully when I read it. Something about our detectors and what an individual graviton effect would cause, falls within that limit; hence undetectable. Does this change that theoretical limit?
I believe LIGO-style detectors would still have this issue. The procedure that is proposed here is more like a gravitational analog of the photo-electric effect. In the photo-electric effect you have an electron which is bound to an atom until a photon with sufficiently high energy knocks it out. In the proposed experiment here they would prepare a bar of a very pure material (e.g., aluminum) and cool it until it is in its ground state. The length of the bar would be chosen so that its resonant frequency would correspond to the frequency of a gravitational wave event. When a gravitational wave passes by, a graviton could excite an acoustic mode in the bar.
Incidentally, these kinds of resonant bars were one of the original ideas for gravitational wave detectors back in the 1960s and 70s. A physicist named Joseph Weber claimed to have detected a number of gravitational wave events back in the 1960s, but it was later determined that these were noise. [1]
Re: Scientists Propose Groundbreaking Method to Detect Single Gravitons
#10I haven't read this paper yet, but it does look interesting. For context, there is a famous lecture by Freeman Dyson [1] in which he studies the question of whether it is possible in principle to detect an individual graviton. He considered a couple of different classes of detectors and his conclusions were mostly pessimistic. The essential problem with many detectors (e.g., something like LIGO) is that any detector…
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