I read last week that scientists had detected gravitational waves from merging blackholes, and indeed the lead scientists have been awarded the noble prize.
Does being able to detect gravitional waves put us any closer to understanding the actual mechanics of gravity? Or is it more a case of we’ve confirmed Einstein’s theory, but are no closer to understanding “how”?
“How” isn’t not hard - mass warps space time as per General Relativity. Energy loss from gravity waves was seen in binary pulsars and the waves themselves were finally confirmed with these recent detection of black hole mergers. I guess to be accurate, with the detection of wave profiles identical to modeled black hole mergers.
The hard questions are the “whys”. These detections don’t help with that, at least not yet.
Can’t not comment “the noble prize.”? Auto-correct strikes again.
With respect, that’s like saying it works because it does.
I think you will find that all of the fundamental forces in physics are like that. If they weren’t then they would not be fundamental.
This. Einstein’s theory is the “how.”
The whys lead to the next set of hows which gives you another opportunity to ask why.
It’s not turtles but whys all the way down.
Why. How. Why. How. Why. How. Why. How. Why. How. Why. How. Why. How.
Why. How. Why. How. Why. How. Why. How. Why. How. Why. How. Why. How.
[sub]Why. How. Why. How. Why. How. Why. How. Why. How. Why. How. Why. How. …[/sub]
So far, all we’ve found with gravitational waves is what we expected to find. As time goes on and we accumulate more detections, we’ll start to learn a little more about just how common these events are, which will be useful and interesting information, but it’s mostly relevant to astronomy, not to physics.
Where we’d really learn more about physics is from the events that we didn’t expect. Unfortunately, with the current instruments that we have, it’s almost impossible to recognize a signal of an unexpected sort. Fortunately, however, there’s a very simple thing we can do to change that. All we have to do is build more detectors, of the same design that we already have and which we already know works.
I thought LISA was the solution…
The biggest difference between LISA and LIGO is that LISA is sensitive to much lower frequencies, and there are a whole bunch of known-known sources for that lower frequency range, so if we launched LISA, turned it on, and didn’t detect those known-known sources, then we’d know that either the instrument or the theory was broken. But LISA is nearly as dependent on template matching as LIGO is, which makes it nearly as hard to use it to detect something unexpected. And while I think it’s definitely worthwhile to iron out all of the engineering kinks in LISA and get it launched, LIGO already has all of the kinks ironed out, and that’s a pretty big deal.
Of course, what would be really ideal would be to build a bunch of LIGOs, and a bunch of LISAs, and finish working the bugs out of the pulsar timing array (unfortunately, we can’t build more of those), and build a bunch of other instruments at other frequency ranges, and run through all of the data from all of them. But we have to start somewhere, and “build more of the thing that already works” is as good a place to start as any, especially in a world of limited funding.
Template matching - think of them as predetermined “sound” profiles that show what a black hole/black hole merger should sound like. The data the detectors picks up is then compared to it and a match means a detection. As Chronos says the noise levels these machines deal with are massive so we “look” for patterns. The problem of course is finding a pattern you’ve never heard before. Imagine standing in a room filled with talking people and trying to listen for “Free Falling” by Tim Petty being hummed by a member of the crowd. Easy right? 
Now imagine trying to detect “song never written” by artist “never born”.
I think Tim Petty qualifies as the latter 
An even better example of template matching is names. You can be in a crowded room full of people holding conversations and not understand any of it… until someone on the other side of your room says your name, and that you’ll hear.
And even just for the expected sorts of signals, you still need a truly massive number of templates. Like, for two black holes merging, you’ll get a different template by changing the mass of one of the holes, or by changing the mass of the other one, or by changing the amount of spin either of them has, or by changing the direction either one is spinning, or by changing the orientation of their orbit prior to the merger. And so you need a different template for each combination of those parameters. And then you still need different templates for various kinds of supernovas, or neutron star quakes, or what have you.
Sigh :smack: