How might g-waves not to exist?

epros
Joined: 21 Jun 05
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Topic 189422

I'm interested what we could do if result of gravity waves search would be negative?
For me it looks impossible case like 2*2 not equal 4.
Gravity exists - it's obvious fact, because everyone feels it in his weight. And if gravity source moved, afaik there would be the only way to thansfer the gravity changes over space - waves.

gravywavy
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How might g-waves not to exist?

Quote:
I'm interested what we could do if result of gravity waves search would be negative?
For me it looks impossible case like 2*2 not equal 4.
Gravity exists - it's obvious fact, because everyone feels it in his weight. And if gravity source moved, afaik there would be the only way to thansfer the gravity changes over space - waves.

yes, as far as we know.

But if that is true, we'd expect to be able to see them, hence this experiment.

If we cannot see them, then we have to ask: how else might this effect occur?

A long time ago, people said that when we rub two things together the heat comes out - thatis the only way afaik we can explain why things get hot when they are rubbed. So somebody realised the effect should be measurable in two different ways:

first: does the rubbed object get lighter?

second: after we have been squeezing the heat out by rubbing for a very long time, does there seem to be any falling off in the amount that is coming out?

Eventually it was realised that both answers were No. Someone found another explanation: that heat was a form of energy not a material substance.

So too, if we cannot find gravity waves, we will be very puzzled. But the answers to that puzzle will no doubt be found. Like alternatives were found to other, older, obvious facts, like the flat earth, like the earth at the centre of the solar system, like the phlogiston theory, and so on.

If we did not bother to check the things we think are obvious, none of those exciting changes in science could have happened. Who knows which way it will go - but if the answer is that there are no gravity waves I will be just as surprised as you.

Just as surprised as Kepler was, when he found that planetary orbits were not the obvious egg shape he set out to find, but the intuitively ugly ellipse he discovered to his horror: how could God have been so clumsy, he wondered.

So if there are no waves, a different explanation will be found, one that fully explains the fact the we have weight, one that fully explains tides, falling apples, and so on. I have no idea what sort of explanation that might be: I just know that in the past many 'obvious' facts have turned out to have alternative explanations.

~~gravywavy

Ben Owen
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RE: I'm interested what we

Quote:
I'm interested what we could do if result of gravity waves search would be negative?

At the moment, it wouldn't be too surprising. The instrument's sensitivity is improving, but it's still at a level where we need to get really lucky to detect something.

But eventually? If there wasn't anything, say, five years from now, then we would know something is drastically wrong with our understanding of the universe.

We wouldn't be inclined to say there's something wrong with relativity's prediction that objects moving in certain ways emit gravitational waves; at least, not without some other evidence. Hulse and Taylor got the Nobel Prize for their observations of a binary pulsar in 1975 (and ever since) that have showed that the orbit is changing just as relativity predicts for the recoil from gravitational waves. After 30 years this observation is not quite competitive with QED and the fine structure constant as the most precise observation (and agreement with theory) ever done by humans, but it's up there.

If we didn't see anything after long enough, we would start drawing conclusions that astrophysical theories of various sorts are wrong. Like if Einstein@Home didn't see anything for five years, we could start ruling out (or at least strongly disfavoring) some theories of neutron star matter.

Hope this helps,
Ben