# Speed of Light Question.
**URL:** https://boards.straightdope.com/t/speed-of-light-question/114119
**Category:** Factual Questions
**Created:** [June 14, 2002, 11:05pm UTC](https://boards.straightdope.com/t/speed-of-light-question/114119 "2002-06-14T23:05:20Z")
**Posts on this page:** 3
**Page:** 2
### Author:  [@ZenBeam](https://boards.straightdope.com/u/ZenBeam)
#### Post date: [June 17, 2002, 8:28pm UTC](https://boards.straightdope.com/t/speed-of-light-question/114119/21 "2002-06-17T20:28:50Z")
> [@](#):
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> Don’t you think it would be better to say that they **transmit** gravitation rather than say that they produce gravitation?
No. I was responding to your statment that gravitons shouldn’t _produce_ gravitation, which is incorrect. I think everyone here understands that gravitons also _transmit_ gravitation.
> [@](#):
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> Is it that gravitons are actually only affecting space/time and indirectly “pulling” other objects towards their area of effect?
It sounds like you’re asking whether gravitons work by curving space, like we visualize in classical GR, versus interacting with other quantum mechanical particles directly, like we visualize with (virtual) photons. I _think_ with quantum gravity, you’d have to _replace_ the curved-space idea with that of particle interactions. If you just include the particle interactions _along with_ the curved space, you’d end up double counting the gravitational effect. (This is similar to the way GR replaces Newtonian gravity. You don’t add the two.) On the other hand, descriptions of quantum gravity always seem to include descriptions of space being “foamy” at the smallest length scales, which suggests curvature of space is still in there. All of which is, I guess, a long-winded way of saying **bump**.
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### Author:  [@ZenBeam](https://boards.straightdope.com/u/ZenBeam)
#### Post date: [June 17, 2002, 9:52pm UTC](https://boards.straightdope.com/t/speed-of-light-question/114119/22 "2002-06-17T21:52:28Z")
> [@](#):
>
> Is it that gravitons are actually only affecting space/time and indirectly “pulling” other objects towards their area of effect?
Thinking about this some more since I posted above, I think this statement is correct, and that my statement that
“with quantum gravity, you’d have to replace the curved-space idea with that of particle interactions.” is incorrect.
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### Author:  [@bryanmcc](https://boards.straightdope.com/u/bryanmcc)
#### Post date: [June 17, 2002, 10:09pm UTC](https://boards.straightdope.com/t/speed-of-light-question/114119/23 "2002-06-17T22:09:57Z")
I think what **Vertigo** is asking (and if not, then I’m just going to ask it myself, 'cause I’ve often wondered the same thing) is this: I’ve seen the electromagnetic force explained as being due to the exchange of virtual photons. Two particles of like charge approach each other, exchange some photons, and the momentum carried by the photons push the particles away from each other. Viola! Repulsion of like charges. What I don’t get is how the exchange of particles can cause _attraction_ (whether electromagnetic, stong, or gravitational). The exchange particles should hit the “parent” particles and cause them to rebound. Yet for some reason they don’t do this. Instead, they draw the parent particles together. Are the exchange particles somehow carrying negative momentum?
-b
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