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Modern physics(and engineering) is kind of absurd. And I mean that in a good way. LIGO? I didn't believe at all that it would ever work. Even when they got dete

Modern physics(and engineering) is kind of absurd. And I mean that in a good way. LIGO? I didn't believe at all that it would ever work. Even when they got detections I kinda thought they were chasing their own tails. Now the evidence is pretty much rock solid that the data is real(multiple facilities, correlations with light observations for neutron star mergers, etc). Then I heard about LISA, which essentially is building this thing in fucking space(different geometry, but same basic concept), with probes somehow orbiting in unison and firing lasers at eachother over ridiculous distances(2.5 million kilometers!). I thought they were raving mad. But pathfinder, the POC, seemed to work, and now they're building the thing. Planned for 2037, but still. When I heard about this project in a spacetime video a few years ago IIRC, again I thought okay, this is too far. It's never gonna work, there'll be too much noise yadda yadda. And it now it looks they might have done it. At this point, if physicists say something is possible, I listen no matter how impossible it sounds.

defrost 3y ago
It takes a while to build these things. My physics professor, David Blair, sketched out the design for LIGO and other detectors back ~1980 and the kinds of technology that would first need to be created in order to get there. The big money and the big builds tend to be in the US (for now, at least, but empires always shift centres over the long time periods) but the ideas come from all over the world. https://www.uwa.edu.au/Profile/David-Blair https://www.uwa.edu.au/Profile/David-Blair
MichaelMoser123 3y ago
so how comes they can't get this fusion thing to work?
- distant_hat 3y ago
  Fusion is easy and you can set off a hydrogen bomb whenever you like, it is turning that energy into electricity that's the hard part.
  - JumpCrisscross 3y ago
    > it is turning that energy into electricity that's the hard part It’s creating a stable, recurring reaction that’s the hard part.
    - stefncb 3y ago
      It's actually making it spend less energy than it creates that's the hard part.
- urinotherapist 3y ago
  Fussion is easy, hyndrogen nukes were detonated decades ago. Ask them about LENR (Low Energy or Lattice Enabled Nuclear Reactor). Cold Fusion topic is reputation-damaging for scientists for decades. I banned multiple times here for "participation in discussion". Now, LENR is used to boost fusors performance by two order of magnitude (for medical purpose).
- __MatrixMan__ 3y ago
  It's only superconducting magnets and 100M degree plasma, how hard could it be?
- JumpCrisscross 3y ago
  > how comes they can't get this fusion thing to work? Fusion energy involves conjuring physics which don’t exist in that form in the known universe. (Stellar fusion happens at lower rates than what we’re targeting. The only reason it works is because stars are so huge.)
  - wolfram74 3y ago
    I think a useful fact to contextualize how much more intense we're hoping to make fusion, is that the volumetric power density (watts per cubic meter) of sol's core (276 watts/m^3) is on the scale of a well run compost pile (50~200)[0]. Since we don't want to make an object as big as the sun's core, we need to make something far, far, far more intense than the sun's core, which is understandably quite hard. [0]https://www.sciencedirect.com/science/article/pii/S2667010021001104 https://www.sciencedirect.com/science/article/pii/S266701002...
    - skinner927 3y ago
      Wow, I never thought of that. It makes perfect sense.
- adrianN 3y ago
  Nobody wants to pay for it. We have other forms of energy that are cheaper and available right now.
  - dotancohen 3y ago
    Unfortunately this is the correct answer, almost word for word how I was going to phrase it. Do long as other forms of energy are inexpensive, we will continue to abuse them no matter the damage.
    - adrianN 3y ago
      Nuclear and renewable energy are two options that are (probably) cheaper than fusion.
- mtlmtlmtlmtl 3y ago
  Can't get it work yet. LIGO took decades to get to work. Progress is being made though.
tedd4u 3y ago
For more materials, measurement, and spacecraft engineering challenges in verifying gravity theory, check out Gravity Probe B [1]. 40+ year effort (spoiler: it confirmed the geodetic and frame-dragging effects of General Relativity). [1] https://einstein.stanford.edu/TECH/technology1.html https://einstein.stanford.edu/TECH/technology1.html
lasc4r 3y ago
I feel like you need to see _this_ spacetime video: https://www.youtube.com/watch?v=4d0EGIt1SPc https://www.youtube.com/watch?v=4d0EGIt1SPc If you think LISA is mad this will blow your mind.
- mtlmtlmtlmtl 3y ago
  I watch pretty much all their videos as they come out, and indeed this one was... pretty out there(pun intended). Somehow I have no doubt it'll be built one day. For now my mind is sufficiently blown by JWST taking spectra of exoplanet atmospheres.
wefarrell 3y ago
This discovery didn't actually involve LIGO, nor any other feats of impressive physical engineering. It was made by observing neutron stars and finding patterns in their unexpected perturbations. Neutron star rotation is so consistent that they are used to calibrate atomic clocks[0]. However some of them were glitching and not rotating as expected, but the glitches were consistent between each other. It turns out they aren't actually glitching, but spacetime is being distorted by massive gravitational waves. [0] https://gizmodo.com/scientists-use-spinning-neutron-stars-to-calibrate-atom-1831327033 https://gizmodo.com/scientists-use-spinning-neutron-stars-to...
- sliken 3y ago
  Indeed, and part of the magic is knowing jupiters position with a very high precision. Said precision was delivered by the Juno probe in 2016 or so. With that precision we now know the earth position with much more accuracy. The trick is the jupiter and sun orbit around a point outside the surface of the sun. Said point (barycenter) is the point the earth rotates around. The increased positional accuracy of the earth allows teasing out the distortion from to various pulsars to use the galaxy as a ligo like gravity wave detector.

defrost 3y ago

It takes a while to build these things. My physics professor, David Blair, sketched out the design for LIGO and other detectors back ~1980 and the kinds of technology that would first need to be created in order to get there. The big money and the big builds tend to be in the US (for now, at least, but empires always shift centres over the long time periods) but the ideas come from all over the world. https://www.uwa.edu.au/Profile/David-Blair https://www.uwa.edu.au/Profile/David-Blair

MichaelMoser123 3y ago

so how comes they can't get this fusion thing to work?

distant_hat 3y ago
Fusion is easy and you can set off a hydrogen bomb whenever you like, it is turning that energy into electricity that's the hard part.
- JumpCrisscross 3y ago
  > it is turning that energy into electricity that's the hard part It’s creating a stable, recurring reaction that’s the hard part.
  - stefncb 3y ago
    It's actually making it spend less energy than it creates that's the hard part.
urinotherapist 3y ago
Fussion is easy, hyndrogen nukes were detonated decades ago. Ask them about LENR (Low Energy or Lattice Enabled Nuclear Reactor). Cold Fusion topic is reputation-damaging for scientists for decades. I banned multiple times here for "participation in discussion". Now, LENR is used to boost fusors performance by two order of magnitude (for medical purpose).
__MatrixMan__ 3y ago
It's only superconducting magnets and 100M degree plasma, how hard could it be?
JumpCrisscross 3y ago
> how comes they can't get this fusion thing to work? Fusion energy involves conjuring physics which don’t exist in that form in the known universe. (Stellar fusion happens at lower rates than what we’re targeting. The only reason it works is because stars are so huge.)
- wolfram74 3y ago
  I think a useful fact to contextualize how much more intense we're hoping to make fusion, is that the volumetric power density (watts per cubic meter) of sol's core (276 watts/m^3) is on the scale of a well run compost pile (50~200)[0]. Since we don't want to make an object as big as the sun's core, we need to make something far, far, far more intense than the sun's core, which is understandably quite hard. [0]https://www.sciencedirect.com/science/article/pii/S2667010021001104 https://www.sciencedirect.com/science/article/pii/S266701002...
  - skinner927 3y ago
    Wow, I never thought of that. It makes perfect sense.
adrianN 3y ago
Nobody wants to pay for it. We have other forms of energy that are cheaper and available right now.
- dotancohen 3y ago
  Unfortunately this is the correct answer, almost word for word how I was going to phrase it. Do long as other forms of energy are inexpensive, we will continue to abuse them no matter the damage.
  - adrianN 3y ago
    Nuclear and renewable energy are two options that are (probably) cheaper than fusion.
mtlmtlmtlmtl 3y ago
Can't get it work yet. LIGO took decades to get to work. Progress is being made though.

tedd4u 3y ago

For more materials, measurement, and spacecraft engineering challenges in verifying gravity theory, check out Gravity Probe B [1]. 40+ year effort (spoiler: it confirmed the geodetic and frame-dragging effects of General Relativity). [1] https://einstein.stanford.edu/TECH/technology1.html https://einstein.stanford.edu/TECH/technology1.html

lasc4r 3y ago

I feel like you need to see _this_ spacetime video: https://www.youtube.com/watch?v=4d0EGIt1SPc https://www.youtube.com/watch?v=4d0EGIt1SPc If you think LISA is mad this will blow your mind.

mtlmtlmtlmtl 3y ago
I watch pretty much all their videos as they come out, and indeed this one was... pretty out there(pun intended). Somehow I have no doubt it'll be built one day. For now my mind is sufficiently blown by JWST taking spectra of exoplanet atmospheres.

wefarrell 3y ago

This discovery didn't actually involve LIGO, nor any other feats of impressive physical engineering. It was made by observing neutron stars and finding patterns in their unexpected perturbations. Neutron star rotation is so consistent that they are used to calibrate atomic clocks[0]. However some of them were glitching and not rotating as expected, but the glitches were consistent between each other. It turns out they aren't actually glitching, but spacetime is being distorted by massive gravitational waves. [0] https://gizmodo.com/scientists-use-spinning-neutron-stars-to-calibrate-atom-1831327033 https://gizmodo.com/scientists-use-spinning-neutron-stars-to...

sliken 3y ago
Indeed, and part of the magic is knowing jupiters position with a very high precision. Said precision was delivered by the Juno probe in 2016 or so. With that precision we now know the earth position with much more accuracy. The trick is the jupiter and sun orbit around a point outside the surface of the sun. Said point (barycenter) is the point the earth rotates around. The increased positional accuracy of the earth allows teasing out the distortion from to various pulsars to use the galaxy as a ligo like gravity wave detector.