# The Naked Scientists Forum

### Author Topic: Why is gravity a weak force?  (Read 7265 times)

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##### Why is gravity a weak force?
« on: 22/02/2009 00:45:07 »
I read in different articles that one way to explain why gravity is so week compared to others forces is that it may leak away into other dimensions .If this is so then if it can leak out is it also possible that it can leak in?
Would gravity leaking in  from the so called multiverse act upon large masses in our universe like galaxies and make them appear to contain more gravity than matter observed?
And what of gravity leaking into our universe where matter is not to be found as in the space between galaxies? What effect on spacetime in our universe would that have? Would that gravity act differently without mass present?
« Last Edit: 23/02/2009 22:34:08 by chris »

#### Vern

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##### Re: Why is gravity a weak force?
« Reply #1 on: 22/02/2009 00:56:27 »
I think you're asking us to speculate about a speculative speculation There's a whole bunch of what ifs in there. String theory has a ways to go before it can get a real hold on gravitation. Each new student of it seems to create their own version.

#### DoctorBeaver

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##### Re: Why is gravity a weak force?
« Reply #2 on: 22/02/2009 09:10:59 »
Saying that gravity may "leak" is not quite right. What is meant is that if there are other dimensions then gravity has more space in which to act and consequently will be weaker.

As an analogy, imagine this. Take a sealed container with a plunger, with the air inside at atmospheric pressure. The plunger is initially near the bottom of the container. Now pull the plunger up. There is still the same amount of air inside but it has greater volume and the pressure will be lower.

The other forces cannot travel in the extra dimension(s) so their effect remains much stronger.
« Last Edit: 22/02/2009 09:13:19 by DoctorBeaver »

#### LeeE

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##### Re: Why is gravity a weak force?
« Reply #3 on: 22/02/2009 16:59:47 »
This issue only really arises if you view gravity as a force; if you view gravitic effects as the consequence of the curvature of space-time it isn't a problem.

To me, it seems that 'forces', in the context of gravity, the electromagnetic force and the two atomic forces, really just describes observed behaviours and effects, but not what the forces themselves consist of in terms of energy or mass.  As such, they don't really seem to exist at all.

This is not to say that the behaviours and effects do not exist, but that in attributing their causes to forces we might be misleading ourselves.  The real problem then, is finding alternate mechanisms to forces to explain the behaviours and effects that we attribute to the electromagnetic and atomic forces.

#### DoctorBeaver

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##### Re: Why is gravity a weak force?
« Reply #4 on: 22/02/2009 19:32:34 »
Of course, LeeE is correct (as always  [:(!] ). My response was describing only 1 of a number of theories.

#### LeeE

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##### Re: Why is gravity a weak force?
« Reply #5 on: 23/02/2009 21:16:16 »
Hmm... if I was always correct, which I know I'm not, I wouldn't be where I am today.

The important thing is that they're all just theories though; some look better than others from one point of view, and the others can look better from a different point of view, but I don't think we really know, one way or the other, at least not yet.

When a flawless GUT eventually turns up, then I think we might have made some real progress, but for now, we're really just making plausible and educated theories.  Very plausible and very educated theories in many cases, but still theories nevertheless.

#### DoctorBeaver

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##### Re: Why is gravity a weak force?
« Reply #6 on: 23/02/2009 21:41:13 »
Do you think we need a GUT? I'd have thought a better understanding of gravity would be enough. Or do you think the 2 are intertwined?

#### LeeE

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##### Re: Why is gravity a weak force?
« Reply #7 on: 23/02/2009 22:08:32 »
Yep, I really think we need a complete GUT if we're to fully be able to digest how the universe works

Unless we're able to resolve everything down to a single expression we're stuck with having to accept an arbitrary number of different factors.  For example, on the one hand it seems that we should be able to resolve everything (except possibly space-time itself) down to energy, but on the other hand, solutions like QM require quite a large family of 'fundamental' particles that by definition cannot be resolved any further.

Now it may turn out to be that there just are an arbitrary number of different fundamental factors and that they cannot be unified, but in that case, how could the BB have worked when it just seems to have comprised energy?

So I'm strongly inclined to think that if everything is derived from energy, via the BB, then everything should be resolvable back to energy, including QM's fundamental particles.

#### DoctorBeaver

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##### Re: Why is gravity a weak force?
« Reply #8 on: 23/02/2009 22:13:42 »
That sounds reasonable

#### LeeE

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##### Re: Why is gravity a weak force?
« Reply #9 on: 23/02/2009 22:28:36 »
Heh - but then when has the universe ever worried about being reasonable?

#### DoctorBeaver

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##### Why is gravity a weak force?
« Reply #10 on: 23/02/2009 22:39:11 »
I meant reasonable in an unreasonable way

#### Vern

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##### Why is gravity a weak force?
« Reply #11 on: 23/02/2009 22:52:06 »
Quote from: LeeE
Yep, I really think we need a complete GUT if we're to fully be able to digest how the universe works

It just so happens that I have one of those. Unification of the forces by considering everything to be electromagnetic. It is an old idea. I think it was first proposed by Maxwell. As far as I can take it, I think a consistent theory could be developed along those lines.
« Last Edit: 23/02/2009 22:55:47 by Vern »

#### DoctorBeaver

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##### Why is gravity a weak force?
« Reply #12 on: 23/02/2009 23:43:14 »
Vern - I don't know enough about that theory to comment.

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##### Why is gravity a weak force?
« Reply #12 on: 23/02/2009 23:43:14 »