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What Will It Mean If LIGO Detects Gravitational Waves?

theguardian.com

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Re: What Will It Mean If LIGO Detects Gravitational Waves?

#21

Post by geuis »

mrfusion wrote: post #5

And conversely what would it mean if we never detect gravity waves? Are there any reasonable theories that posit that gravity waves don't exist?

It means that at this point, ground based detectors probably won't work due to the massive amount of background noise (activities from people, geological activity, etc). There are plans for detectors in space that would not suffer the same problems.

There's little reason, almost none at all, to think they don't exist. The standard model clearly predicts they should exist, and non-direct evidence has been seen already.

Re: What Will It Mean If LIGO Detects Gravitational Waves?

#23

Post by neolefty »

ars wrote: post #20
TTPrograms wrote: post #16

Earlier quoted context omitted.

Regarding reasons for doing this, there's the hope that more sensitive systems could function as "gravity telescopes", enabling charting the locations of massive bodies that would emit gravity waves. This could potentially allow for confirmed observations of physical regimes not accessible by experiment on Earth, much like other astronomical observatories.

How can you do that? There is no way to block gravity, so you can not make directional observations, the waves you see are the linear sum of all the waves in the universe. Although I do wonder if an array of detectors might be able to use time differences in the arrival of the waves to differently located detectors, and some math to get some directional hints.

Time differences: Exactly that. Which is why having 3 or 4 synchronized detectors is necessary for narrowing down the direction of a source. (3 minimum, 4 to reduce noise.)

Re: What Will It Mean If LIGO Detects Gravitational Waves?

#24

Post by robhu »

cornholio wrote: post #18

I hope Forbes realizes that blocking access to users with add blockers is not only a way to get rid of freeloaders, but also a way to ensure those people avoid Forbes altogether in the future and also avoid passing around Forbes links, since not everybody can see them. Alienating your audience is a very expensive mistake and the cost savings related to page serving are negligible. While I can turn off my add blocker,…

They do not detect uBlock Origins.

Re: What Will It Mean If LIGO Detects Gravitational Waves?

#25

Post by porsupah »

dang wrote: post #3
oneworld wrote: post #2

Great explanation of what it might mean: http://www.forbes.com/sites/startswithabang/2016/02/09/what-... Also, how effing cool is it that we are able to detect changes in spacetime itself!

An announcement of an announcement is always off-topic here, so we changed the URL from http://www.ligo.org/news/media-advisory.php to that article, which is much more substantive. Thanks! The announcement itself, of course, will be on topic when it happens, but we can be patient.

FWIW, there's also https://www.theguardian.com/science/2016/feb/09/watch-this-s..., with no adblock issues.

Re: What Will It Mean If LIGO Detects Gravitational Waves?

#26

Post by ISL »

mrfusion wrote: post #5

And conversely what would it mean if we never detect gravity waves? Are there any reasonable theories that posit that gravity waves don't exist?

It would be a spectacular conflict with the Hulse-Taylor binary pulsar system, whose orbital decay is exactly in line with the prediction for energy loss through gravitational waves.

Re: What Will It Mean If LIGO Detects Gravitational Waves?

#27

Post by wiwillia »

cornholio wrote: post #18

I hope Forbes realizes that blocking access to users with add blockers is not only a way to get rid of freeloaders, but also a way to ensure those people avoid Forbes altogether in the future and also avoid passing around Forbes links, since not everybody can see them. Alienating your audience is a very expensive mistake and the cost savings related to page serving are negligible. While I can turn off my add blocker,…

I hear what you're saying, but I'm not sure I agree with the argument that this approach is not in their interest (I also use an ad blocker by the way, not preaching just being practical). I would bet that ~50%+ of people are choosing to disable their ad blocker to view Forbes content once they got stopped (I did), and that that the value driven by that increase in ads served outweighs the cost of not having the small % of users who refuse to turn off ad blockers not share their links.

I can also 100% guarantee they split tested this, before rolling it out, to make sure it was the right cost/benefit choice.

Re: What Will It Mean If LIGO Detects Gravitational Waves?

#28

Post by ISL »

madaxe_again wrote: post #7

I'm curious as to why ligo is the only project ever mentioned, particularly given that they have to work with virgo and geo600 to be able to triangulate their observations - a two axis interferometer only gives you partial information. Better PR team?

If you look carefully at the press release, the group that's presenting on Thursday is the LSC, the LIGO Scientific Collaboration, which includes VIRGO and GEO. It's one big group, as everyone in the field shares hardware techniques and analysis techniques.

Re: What Will It Mean If LIGO Detects Gravitational Waves?

#29

Post by antognini »

Not only will the discovery of gravitational waves confirm an important prediction of general relativity, but it will be the first test of GR in the strong gravity regime. So far, all the tests of GR have been in the weak gravity regime, where Newton's law of gravity is approximately correct. The precession of Mercury's perihelion, gravitational redshift, the gravitational deflection of light, and the measurement of frame dragging by Gravity Probe B have all been probing similar regions of parameter space --- slow velocities (compared to the speed of light) and weak gravity (i.e. far from the event horizon of a black hole).

If the rumors are true that LIGO has detected the merger of two black holes, the observed waveform will be the first test of the predictions of general relativity in the strong gravity limit. This is the most interesting limit because this is where physics diverges the most from Newtonian gravity. Moreover, it's much easier to detect deviations from general relativity in this limit.

LIGO's detection won't be the only test of GR in the strong gravity limit for too long, however. The Event Horizon Telescope has been trying to directly observe the event horizon of the supermassive black hole at the center of the Milky Way (or its shadow, anyway) and should have its first images within a few years.

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