Does light produce a gravitational field?

reply to post by buddhasystem

I see that you have a major problem with mathematical expression E=mc2.

Uh, that equation basically tells you how much energy you can get out of something; i.e., how much a given amount of mass can do work. It states nothing about generating gravitational fields.

And ponder this -- Sun is losing mass by emitting massless photons... Who of course do possess energy.

Uh, no. The emission of mass-less photons is a secondary effect of the energetic reactions that take place within the sun. At the onset of stellar birth, a star is typically dense, as it matures going through it's sources of fuel it get's larger and less dense. The denser the source of mass, the more gravity it has, the less denser the mass, the less gravity it has.

An example is to look at the Earth. At it's current density it has a certain gravitational force exerting upon us right now. If we compress the Earth, making it more dense we increase it's gravitational exertion.

@Arbitrageur

If E is the energy of the photon, plug that into E=mc^2 and you get the relativistic mass, m=E/(c^2)

Right, *if* the coherent beam of light was directed at the stationary atom, then it would impart energy/force upon that atom. The photon is mass-less, it contains no real mass to generate a gravitational field. Again, let's bring up Einstein who correlates mass to gravity and gravity to mass. A photon has no real mass, but as a packet of energy it can impart a relativistic mass upon interaction with real mass as per E=MC2 dictates.

Then how do you explain the source I cited earlier regarding the gravitational effect of light beams on other light beams?

I haven't read through the link yet. I would hazard a guess that there is some interaction going on due to electromagnetic phenomena that hasn't been accounted for or is being simply overlooked. Electromagnetic phenomena is orders of magnitude stronger than the weak interaction of gravity. Seeing as light is an electromagnetic phenomena, I can only suppose that there is something along that line at play there.

Unless of course you can point out in the article where they have accounted for any such effect and ruled it completely out and have conclusively proven that this is a pure gravitational phenomena and not a simple empty claim, considering we can't even directly measure gravity and only know of it's existence through it's effects.

Originally posted by sirnex
reply to post by buddhasystem

 

I see that you have a major problem with mathematical expression E=mc2.

Uh, that equation basically tells you how much energy you can get out of something; i.e., how much a given amount of mass can do work. It states nothing about generating gravitational fields.

Wrong. It's called "equivalence". Equal sign works both ways, you know.

And ponder this -- Sun is losing mass by emitting massless photons... Who of course do possess energy.

Uh, no. The emission of mass-less photons is a secondary effect of the energetic reactions that take place within the sun. At the onset of stellar birth, a star is typically dense, as it matures going through it's sources of fuel it get's larger and less dense. The denser the source of mass, the more gravity it has, the less denser the mass, the less gravity it has.

All of the above is 100% wrong. The gravity of the body has nothing to do with density. I can't imagine where you got such an inane proposition. One pound of cottonwool has the same mass as one pound of lead and exerts same amount of gravitational pull at the same distance.

Emission of photons is one of the principal ways Sun is shedding energy, which comes from its mass -- so mass goes down as well.
I can give ou another example -- take an electron and a positron and let them annihilate. There is nothing left in their place except for two photons. Which of course, carry the equivalent of mass of the pair that no longer exist.


[edit on 8-6-2010 by buddhasystem]

Originally posted by sirnex

Then how do you explain the source I cited earlier regarding the gravitational effect of light beams on other light beams?

I haven't read through the link yet.

In that case perhaps we can continue with some better informed discussion after you have so you can point out the errors in the mathematical application of Einstein's theory.

Here's a link where you can download the paper:

en.scientificcommons.org...

The paper is a mathematical application of Einsteins' general relativity. The effect is gravitational according to the equations.

Expressions are obtained, in accordance with Einstein's approximate solution of the equations of general relativity valid in weak fields, for the effect of steady pencils and passing pulses of light on the line element in their neighborhood. The gravitational fields implied by these line elements are then studied...

The one unique case where the gravitational attraction from the light becomes zero is on a parallel beam of light. This I suppose is because they are traveling in the same direction at the same speed so the relativistic effect becomes zero. But according to that paper other beams of light not in parallel, as well as massive particles, will be affected by the gravity of the beam of light, (though almost imperceptibly so).

[edit on 8-6-2010 by Arbitrageur]

reply to post by buddhasystem

Wrong. It's called "equivalence". Equal sign works both ways, you know.

Well now that was a very pointless inconsequential statement. Was I arguing against the equivalency of the equation? No, not at all. I do see where you are going however, and no, it doesn't work that way and that is not even close to what the equation tells us.

All of the above is 100% wrong. The gravity of the body has nothing to do with density. I can't imagine where you got such an inane proposition. One pound of cottonwool has the same mass as one pound of lead and exerts same amount of gravitational pool at the same distance.

Your trying to equate a specific mass to density.

Right, so, let's use the applicable definition before we blindly argue, shall we?

A measure of the amount of matter contained by a given volume

link

A black hole forms when a star or other matter collapses to such a small size that the escape velocity equals the speed of light. This point where the escape velocity equals the speed of light is called the event horizon or Schwarzschild radius. To what density must a star be compressed so that its escape velocity equals the speed of light?

Read more at Suite101: Calculating Density of Black Holes: How Much Must Mass & Energy Be Compressed to Form an Event Horizon astrophysics.suite101.com...

Wow, would you look at that. The density of a black hole is what gives it such a massive gravitational field, well that and the more mass it contains before initial compression can generate an even larger field. If the Sun, with it's given mass *now* were to be compressed to a smaller, denser state it would indeed begin to generate more and more gravity until it eventually forms into a black hole. Same mass, just more dense exerting a greater influence upon the surrounding space.

edit:

Point being, the density i.e. amount of mass in a given volume can and does also account for how much gravitational 'pull' an object will have.

Emission of photons is one of the principal ways Sun is shedding energy, which comes from its mass -- so mass goes down as well.
I can give ou another example -- take an electron and a positron and let them annihilate. There is nothing left in their place except for two photons. Which of course, carry the equivalent of mass of the pair that no longer exist.

Again, another very pointless inconsequential statement. The Sun does not work by total annihilation of it's mass into energy. When the sun consumes it's fuel, there is indeed matter left over. Hydrogen fusion -> Helium fusion -> etc., until it can no longer sustain fusion with each step of the way causing the sun to grow more massive in size and less denser. I agree that some energy is lost during the fusion process as photonic energy, but again this is a secondary effect and not the main complete reason as to why they sun expands as it matures.

@Arbitrageur

In other words it is mostly assumption that a virtual non-existent mass that only surfaces upon interaction by imparting the force of it's energy upon a particle containing real mass can some how magically generate a real physical force when interaction only with another virtual non-existent mass. To top it all off, I saw no mention that the paper has conclusively disproved any other quantifiable and measurable effect acting upon this electromagnetic phenomena.

[edit on 8-6-2010 by sirnex]

[edit on 8-6-2010 by sirnex]

Originally posted by sirnex
reply to post by buddhasystem

 

Wrong. It's called "equivalence". Equal sign works both ways, you know.

Well now that was a very pointless inconsequential statement. Was I arguing against the equivalency of the equation? No, not at all. I do see where you are going however, and no, it doesn't work that way and that is not even close to what the equation tells us.

Again, if you fail to read it, tell me what happens to two annihilating particles. Where did the mass go?

Wow, would you look at that. The density of a black hole is what gives it such a massive gravitational field, well that and the more mass it contains before initial compression can generate an even larger field.

If you have a black hole and you measure it's pull at distance X (this being a suitably large number, say same as between Earth and the Sun), and you have a common star of same mass at same distance, the force of gravity will be same.

Point being, the density i.e. amount of mass in a given volume can and does also account for how much gravitational 'pull' an object will have.

See my point about observing an object from a distance larger than its radius (above).

Emission of photons is one of the principal ways Sun is shedding energy, which comes from its mass -- so mass goes down as well.
I can give ou another example -- take an electron and a positron and let them annihilate. There is nothing left in their place except for two photons. Which of course, carry the equivalent of mass of the pair that no longer exist.

Again, another very pointless inconsequential statement. The Sun does not work by total annihilation of it's mass into energy.

Oh yeah it does, not by annihilation but by conversion of mass into energy. If you really didn't know that, it's time to hit the books!
Start here:
en.wikipedia.org...

reply to post by buddhasystem

Again, if you fail to read it, tell me what happens to two annihilating particles. Where did the mass go?

In the example you have provided, the mass is converted to energy and in that particular case its energy is in the electromagnetic spectrum as photon's and gamma rays. *Not* converted to gravity.

If you have a black hole and you measure it's pull at distance X (this being a suitably large number, say same as between Earth and the Sun), and you have a common star of same mass at same distance, the force of gravity will be same.

Another wonderful very pointless and inconsequential statement. You could do that to every massive object in existence. It's still moot to the point that the denser an object is the more gravitational pull it will exert at a specified distance. If the sun were to collapse into a black hole right now, the Earth or probably any of the planets would not stay in their nice tidy little orbits they currently preside in, instead they would steadily begin to gravitate towards this new black hole, eventually getting consumed by it.

See my point about observing an object from a distance larger than its radius (above).

Right, if your outside of an objects gravitational influence, you won't be affected by it. How many very pointless and inconsequential statements are you going to spout?

Oh yeah it does, not by annihilation but by conversion of mass into energy. If you really didn't know that, it's time to hit the books!
Start here:

Now your spouting arguments for the sake of spouting arguments.

Allow me to post my statement again. The Sun does not work by total annihilation of it's mass into energy. The example of mass/energy conversion you had provided is total annihilation and you then even agreed that this is not how the sun works as stated above (in bold). As I pointed out as well, the Sun works through nuclear fusion as it's main source of energy, fusing atoms into other atoms and getting less dense, thus expanding as it does so. The release of photon's is nothing more than a byproduct of this fusion process. It is not the main total complete reason why the Sun loses mass as it matures through each stage of fusion.

Technically this doesn't apply to all stars of course, I am only using this example in relation to the sun as its been mentioned that our star will end it's life as a red giant. The other extreme is of course ends with the mass of a star collapsing at each stage ending in a white dwarf or black hole, depending on it's original mass.

yes, I honestly believe light creates a gravitational field. I am very aware that light has no mass, but it is a form of energy. So I believe on a quantum level it does effect gravity. The question is whether it creates a possitive or negative effect on gravity. It has been proven that a very fast spinning super-conducting disk can create a "negative gravity bubble", it would be very interesting to see what kind of effect light actually has. I encourage all people to try their own experiments and leave behind the status-quo scientists.

Originally posted by sirnex
reply to post by buddhasystem

 

If you have a black hole and you measure it's pull at distance X (this being a suitably large number, say same as between Earth and the Sun), and you have a common star of same mass at same distance, the force of gravity will be same.

Another wonderful very pointless and inconsequential statement. You could do that to every massive object in existence. It's still moot to the point that the denser an object is the more gravitational pull it will exert at a specified distance. If the sun were to collapse into a black hole right now, the Earth or probably any of the planets would not stay in their nice tidy little orbits they currently preside in, instead they would steadily begin to gravitate towards this new black hole, eventually getting consumed by it.

I've got to go with buddhasystem on this one, with the qualification provided that the distance is a suitably large number.

Sirnex your statement would be right at close distances, but only because the differences become significant at closer distances. At larger distances, the gravitational forces of a more or less dense object of the same mass approach the same value just as buddhasystem said.

Edit to add:

I think the Earth is far enough away from the sun to make the difference in gravity pretty small if the sun collapsed into a black hole. Maybe the difference won't be zero, but it won't be big enough to suck the Earth into the black hole. I've never done the math to check it, maybe I will if I get bored sometime. Or have you already done the math? You sounded pretty confident the Earth would get sucked in.

Apparently NASA agrees with me and buddhasystem that the Earth wouldn't get sucked in:

What would happen to Earth's orbit if the Sun became a black hole?

If a one solar mass black hole were to suddenly replace the Sun at the center of our solar system, the orbits of the planets would not change. This is because the physical laws that determine the orbital motion of the Earth depend only on the actual mass of the Sun, and not on whether it is distributed within a sphere (like the Sun) or at a point (like a black hole). I hope that answers your question.

Regards,
Padi Boyd,
for the Ask an Astrophysicist

[edit on 8-6-2010 by Arbitrageur]

Originally posted by sirnex
reply to post by buddhasystem

 

Again, if you fail to read it, tell me what happens to two annihilating particles. Where did the mass go?

In the example you have provided, the mass is converted to energy and in that particular case its energy is in the electromagnetic spectrum as photon's and gamma rays. *Not* converted to gravity.

So you do think that mass would simply disappear for an external observer?

If the sun were to collapse into a black hole right now, the Earth or probably any of the planets would not stay in their nice tidy little orbits they currently preside in, instead they would steadily begin to gravitate towards this new black hole, eventually getting consumed by it.

All right now, your knowledge of physics is evidently non-existent since you subscribe to such medieval notions. I'm sorry but since you repeatedly called my statements "pointless" I don't have to be nice to you, do I? So I'm free to call you an ignoramus that you are, unwilling to learn to people with training in the subject.

See my point about observing an object from a distance larger than its radius (above).

Right, if your outside of an objects gravitational influence, you won't be affected by it. How many very pointless and inconsequential statements are you going to spout?

You can't really be outside of an object's "sphere of gravitational influence", there is no cut-off.

Oh yeah it does, not by annihilation but by conversion of mass into energy. If you really didn't know that, it's time to hit the books!
Start here:

Now your spouting arguments for the sake of spouting arguments.

No, I'm "spouting" arguments just trying to find somebody home, but it doesn't work too well. Regardless of whether conversion is 100% or 0.1%, the mass of the Sun is converted to energy, and that's that. That is the crux of the energy-generating machinery inside that star. If you visit the Wiki link I kindly provided and actually read it, there is a succinct note right below the diagram with nuclei.

reply to post by supaflyrobby


Interesting question. The answer should be that the atom and light beam would accelerate towards each other, resulting in bent light and a displaced atom.

@others:
If the sun somehow turned into a black hole then of course the strength of gravity at a distance from centre greater than the radius of the original sun will be the same for a period of time. After that we would have to take into account the mass loss rate of the black hole and the sun.