[OT] Black Holes Merge--Universe "wobbles"

[Umbran]

Well, yes and no. Like a lot of the evidence of quantum mechanics and astrophysics, the evidence is perturbative.

LIGO hasn't published solid results yet. So far, gravity waves have not been clearly detected, perturbatively or otherwise.

The math sort of demands it

Well, you aren't the only physics student here, me hearty. And any decent scientist knows darn well that what the math demands is not the issue - that'd be the tail wagging the dog. Our math does not determine what the Universe does. The world does what it darned well pleases, and we hope to find the math that matches. We may have some faith that our current math is good, and that the world will be found to match it. But that isn't proof.

Remember - as a general policy, if you stick too hard to your maths, rather than to empirical evidence, you wind up rather like those guys who believed in the aetheric electromagnetism...

 

[Tom Cashel]

Remember - as a general policy, if you stick too hard to your maths, rather than to empirical evidence, you wind up rather like those guys who believed in the aetheric electromagnetism...

No, no, no...stop right there...wait a sec...

You're about to utterly annihilate my worldview, aren't you?

 

[Wayside]

LIGO hasn't published solid results yet. So far, gravity waves have not been clearly detected, perturbatively or otherwise.

Well, like I said.. you're right. There is no direct detection. Still, the gluon, the photon and the weak gauge bosons are all experimentally verified (messenger particles of the other 3 forces), and by perturbative I meant more or less as you say, that is "not been clearly detected." Anyway, gravity is by far the feeblest force.. I'm not holding my breath waiting for the smallest bundle of it to be detected.

Well, you aren't the only physics student here, me hearty. And any decent scientist knows darn well that what the math demands is not the issue - that'd be the tail wagging the dog. Our math does not determine what the Universe does. The world does what it darned well pleases, and we hope to find the math that matches. We may have some faith that our current math is good, and that the world will be found to match it. But that isn't proof.

Remember - as a general policy, if you stick too hard to your maths, rather than to empirical evidence, you wind up rather like those guys who believed in the aetheric electromagnetism...

No, it is not proof; neither can you prove to me that you are anything more than a walking talking case of Searle's Chinese Room. Your world would fall apart if you didn't rely so heavily such basic assumptions. Though I do not stick to my math (because I don't do math), I suppose I work too much in philosophy ever to accept defeat on epistemological grounds. It's logic (which can be very perturbative) or nothin!

err.. physics student? Actually I havn't taken a math class since high school, which would be about 4 years ago. Nope, my degree is in English and Latin. My name is from Shelley, my sig is from Nietzsche, and now I go to read Propertius . Henceforth I will leave physics talk to the physicists.

 

[Neowolf]

I came in just to see if my bet with myself was correct.

"Self," I said. "I bet you anything that there's a Cthulhu reference within.... say... the first five posts on this thread."

Thanks Tom Cashel!

You know Great Cthulhu would punish us otherwise...

 

[bolen]

This is what I work on so I will try to explain some things

1) Gravitational waves do travel at c. If you believe in Einstein's theory nothing can travel faster then that. Note: you might be saying, "well they said that about flying faster then sound, now planes fly at Mach 2 and 3. So these physicists are just underestimating technology." Well no, it turns out that as you move faster and faster time is moving slower for you and you don't measure distances the same.

Think about this you are on a train moving at 30 m/hr you thow a ball at 30 m/hr in the direction that you are moving. Now I am on the ground I would say that the ball is moving at

30 + 30 = 60 m/hr

Now instead of a ball you have a flashlight and lets change the train into a rocket which is traveling at half the speed of light. How fast would that light be moving to me on the ground. you might be tempted to say that it is moving at 1.5 c. WRONG!! It is still moving at c. How can this be? It is because our definitions of time and space are linked to what reference frame we are measuring in. Both you and I say that the light is moving at c, what we do not agree on is the definition of length and time.

This is called special relativity.

2) So what is a gravity wave. well lets talk about electromagnetic waves first. If I accelerate a charge (shake it up and down as in what happens in a radio tower), it emits a electromagnetic wave. The same thing goes on with masses and gravity. But remember gravity is about 10^40 times weaker then the electromagnetic force. So in order to get a gravity wave to measure we need a very massive object (such as a black hole or a neutron star)

3) What will LIGO see? well the esimates that I have heard (I am not on on that experiment, just in the field) is that the advanced LIGO should be able to detect a GW of amplitude 10^-22 (that is a unitless number because it is just a ratio of stress/strain) That should enable us to see a BH-BH merger at the virgo cluster. We should have a few events per year (again I am going by memory of a talk I heard a few months ago. BH-BH mergers are not the only source however. we are also looking for Neutron Star -BH and NS-NS. In addition we thing there should be a background of primordial GW left over from the Big Bang. (good luck in seeing that however) This would be analogous to the background 3K radiation that we see in the EM spectrum.

4) GW have been seen indirectly. In the 1970's two physicists were observing a Binary pulsar system. Thay saw that the system was loosing energy. This loss of energy exactly agrees with what one would calculate from General Relativity for loss due to Gravitational radiation (gravity waves). They won the Nobel prize in 1996 (I think that is the date) for this.

5) As far as gaming for a realistic sf game. I cant imagine a place in our universe where GW would play a role, unless you are role-playing physicsists doing work on LIGO and I doubt anyone does that.

6) GW are hoped to provide a new window into astronomy and are useful just as radio telescopes are. (that is after we detect them, which I am fairly confident we are) The money we are talking about here is on the order of a hundred million (not a lot for a huge science project, compare this to the SSC or LHC)

Hope this helps clear stuff up

 

[bolen]

Gravity waves are classical physics and show nothing about the quantum nature of gravity. so your argument about gauge bosons for the standard model is kinda moot. sorry.

 

[bolen]

bump

 

[Ulrick]

If they said it was going to happen in 15 hours, do you really think that I would be wasting time on this messageboard?

LOL

Yes. I think you would.

 

[Zappo]

LOL

Yes. I think you would.

Damn! The sad bit is that you're probably right!

 

[Wayside]

Gravity waves are classical physics and show nothing about the quantum nature of gravity. so your argument about gauge bosons for the standard model is kinda moot. sorry.

Meeeeeee? My fault, I was referring to gravitons even though the people talking about LIGO were referring to waves. My thinking was "if gravitons travel at c, then gw's must also," all other things being equal, that is.

I'm curious though, now that I think about it: do gravity waves always travel straight ahead? I mean, there are a lot of ways that light gets pushed around (not the least of which is gravity)--does anything push gravity around?