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Does photons cause gravitation?

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we hope gravity is quantised, because it would make things all nice and fit.

And yes, I think i asked my teacher this question and he said that the two beams do attract each other

Reply 21

Jonatan

AntiMagicMan

String theory isn't much help either, though physicists like to talk about it, no one can get the equations to make much sense and even when they have equations that look good, no one knows how to solve them or even use them :tongue:

I think one phycisist once said that calculating the electron spin from string theory was like trying to calculate a persons behaviour from the configuration of the elementary particles of the brain.

Reply 22

Willla2

well i dont like string theory atm. The idea is about as scientific as it is to say God created us!

Reply 23

jpowell

Exactly, until it can make predictions it is just something for bored physicists to write papers on :biggrin:

Reply 24

Jonatan

Willla2

well i dont like string theory atm. The idea is about as scientific as it is to say God created us!

There is one MAJOR difference. String theory agrees with other theories which have been tested scientifically. It is also the ONLY hypothesis that is self consistent. Of course it should perhaps be called string-hypothesis rather than theory but still...

Reply 25

Willla2

it's still a big like god though. God is consistent with other theories. It explains where we've come from and all. I'm still waiting for some testable predictions!

Reply 26

Jonatan

Willla2

it's still a big like god though. God is consistent with other theories. It explains where we've come from and all. I'm still waiting for some testable predictions!

The idea behind god is that it is impossible to test his existance. String theory makes a lot of predictions, however, and perhaps in time they will be testable. String theory is also directly relevant to the theories we do have. Without it you cannot unite relativity and quantum mechanics. At least not yet.

Reply 27

jpowell

Hehe, even with it you cannoy unify them, there is still a lot of work :biggrin:

Reply 28

john !!

Can a photon's energy not be manifested as mass, contributing to gravity?
I know that gluons are highly energetic and so contribute largely to the gravitational attraction between protons and neutrons, why can't photons be as well? :biggrin:

Reply 29

username9816

mik1a

why can't photons be as well? :biggrin:

Isn't it infitessimal and hence doesn't contribute to gravity? It is a quanta of electromagnetic radiation after all; although I suppose it does depend on the type of photon it is.

e.g.) A gamma photon would be more energetic than a photon of light, and hence thinking in your terms where energy is effectively mass (mainfested into mass as you described), then I suppose a gamma photon would be more likely to experience graviatational effects.

Although I'm sure that because it's mass is so infitessimal, even as an exchange particle, then it couldn't feel gravitational forces. i.e.) The mass isn't considerable enough.

That's my view anyway. :smile:

Reply 30

jpowell

The infinitesmal is a badly defined concept and has no meaning. The gravitational influence of a photon is not infinitesmal, simpy too small to measure or detect.

Reply 31

Jonatan

mik1a

Gluons do not contribute to gravitational atraction, they give rise to the strong nuclear force which is much stronger than gravity at the distances involved.

Reply 32

john !!

Jonatan

Gluons do not contribute to gravitational atraction, they give rise to the strong nuclear force which is much stronger than gravity at the distances involved.

Are you sure?

Reply 33

jpowell

I don't know whether he is sure, but I certainly am.

The name of the hypothetical vector boson for gravitation is the graviton.

Reply 34

username9816

AntiMagicMan

simpy too small to measure or detect.

That is pretty much the definition, or an alternative wording but with the same meaning, to "infitessimal". :rolleyes:

Reply 35

Jonatan

mik1a

Are you sure?

Quite certain.

Check this site to learn more:
http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html

Reply 36

jpowell

Invisible

That is pretty much the definition, or an alternative wording but with the same meaning, to "infitessimal". :rolleyes:

Sorry, I was thinking of the mathematical concept of the infinitesimal which means something similar but still distinct. There is however another definition which makes sense in the context of your statement. I apologise for any confusion.

Reply 37

PhillRamsden

if a photon has mass, as there is squillions (or more) of them (if you disagree, see zero point mass) the universe would collapse.

Phill

Reply 38

john !!

Jonatan

Quite certain.

Are you sure about the part that gluons don't contribute to gravity though? If I could find it, I'd quote Brian Greene when he said something along the lines of "since gluons are very energetic, they contribute to the gravitational pull of a nucleus".

Roger Penrose's new book is out now and apparently it says how he is skeptical about string theory, and he puts forward some other unifying theories. Unfortunately if you want to read only that part, you have to buy the whole 1100 page book!

:tongue:

Reply 39

jpowell

PhillRamsden

if a photon has mass, as there is squillions (or more) of them (if you disagree, see zero point mass) the universe would collapse.

Phill

I'm sorry that is stupid. There is no easy way to tell you how wrong you are. It is not about how many there are, it is about how much energy they contain.

Also a squillion isn't a number.