# The Naked Scientists Forum

### Author Topic: In gravitational waves, is the amount of space changed?  (Read 2096 times)

#### Atomic-S

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##### In gravitational waves, is the amount of space changed?
« on: 21/01/2011 05:31:10 »
Inasmuch as the general theory of relativity predicts that if 2 objects floating in free space, separated by some distance,encounter a gravitational wave (of suitable polarization), the distance between them will vary with time, and inasmuch as neither particle will feel accelerated by reason of its freely floating condition, would it be correct to say that a gravitational wave does not affect objects, but affects only the space between them? In this case that would mean that space was actually being alternately inserted and removed between them. (Raising the interesting possibility of parking your car in crowded conditions not by moving the other cars present, but by stuffing some space between two of them and then parking there.)

#### syhprum

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##### In gravitational waves, is the amount of space changed?
« Reply #1 on: 21/01/2011 12:10:03 »
This whole field is covered by an excellent article here, an interesting point concerning the low power of gravitational waves is that the power emitted by the Earth orbiting the Sun is 200 watts

http://en.wikipedia.org/wiki/Gravitational_wave

#### yor_on

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##### In gravitational waves, is the amount of space changed?
« Reply #2 on: 21/01/2011 20:21:19 »
The amount of space remains the same as far as I know. It's the same procedure as when making a Black Hole, 'compressing' matter. Space is a classical nothing and what we call 'gravity' is something closely associated with just matter. So if I would assume for example a 'infinite gravity' existing at some plane outside our observation, aka QM does with 'virtual particles' then I would have to assume that what we see actually would be a retarding effect applied on that 'infinite gravity' by matter :)

Which I'm wondering about in fact?
Nice ..
heh
==

The topology will change 'locally' where such a wave propagates though. But 'space' as such is still a 'nothing', you can't define it as being 'compressed' for example. If you do you would have made it into a 'medium', thereby also invalidating the ideas we have of relativity, all as I see it.
« Last Edit: 21/01/2011 20:44:13 by yor_on »

#### Atomic-S

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##### In gravitational waves, is the amount of space changed?
« Reply #3 on: 29/01/2011 05:33:54 »
Having now read much of http://en.wikipedia.org/wiki/Gravitational_wave, it seems to  me to be saying pretty much what I was saying. As to the notion that space is nothing, the strongest argument against that is that space has properties. For example, it has 3 dimensions (4 if you include time). Why would nothing have a specific number of dimensions different than zero? Also, space is capable of being distorted, and the distortion can be changed by altering the arrangment of masses within it. As for example, when measuring the circumferance divided by the diameter of a circle where there is no matter present, compared to when a substantial mass exists within the circle. It is difficult to understand how nothing can have properties that can be changed. If you shut off your monitor, there is no picture. However, the monitor screen still has properties: it has effectively 2 dimensions and a certain diagonal size. It will still be CRT, LCD, or some other technology. It may be blank, but it is still a screen.

#### yor_on

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##### In gravitational waves, is the amount of space changed?
« Reply #4 on: 03/02/2011 21:12:56 »
Nicely stated Atomic-S. The vacuum is classically seen as being empty. But depending on from where you look at it you can state it as a quantum foam, or filled to the brim with virtual particles, gluons, etc.

But it is 'empty' and it have no 'friction' as tested when looking for an aether. That we expect it to behave differently from a QM perspective is another thing. Down there you don't 'exist' as far as I know :)

When it comes to 'dimensions' I think Einstein made the best explanation of it that I know. He called the universe 'SpaceTime' meaning that it is a 'whole concept' not three dimensions plus time, rather that it 'sits together' indivisibly. If that is right we will find space as a natural ingredient, possibly you might imagine a 'universe' where space could have a 'density', but then the light constant as well as a lot of other constants would be different I think. It's not that it is wrong to see Space as 'something', I do it too at times, but classically it still is empty, and that one is proven a long time ago.

#### The Naked Scientists Forum

##### In gravitational waves, is the amount of space changed?
« Reply #4 on: 03/02/2011 21:12:56 »