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mjordan2nd
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Is there any experimental evidence that pure energy (massless) can curve spacetime?
Orodruin said:Gravitational influence on the elementary particle level has not been observed for massive nor massless particles.
This is the effect of space-time curvature on elementary particles, the OP wanted evidence of the effect of "pure energy" on space-time.Vanadium 50 said:It has been shown that neutrons fall (McReynolds; Collela, Overhauser and Werner) , and that photons are redshifted (Pound-Rebka).
mjordan2nd said:Let me rephrase: is there experimental evidence that a particle with 0 rest-mass by itself will warp spacetime?
Yes. It's a good example, and you beat me to it.Ibix said:is nuclear binding energy an example?
So - if only massive particles produced spacetime curvature then "gravitational charge" would depend on nucleon number (or very very nearly so) not mass. Thus the Eotvos experiments would not have the outcome they did.Nugatory said:Yes. It's a good example, and you beat me to it.
Well, charge is frame invariant, unlike energy/momentum.Orodruin said:There is no such thing as "pure energy". Energy is a property we use to describe how the world behaves around us. You could just as well ask for "pure charge" or "pure angular momentum".
Orodruin said:This is the effect of space-time curvature on elementary particles, the OP wanted evidence of the effect of "pure energy" on space-time.
I do not doubt that light gravitates. As mentioned already, if it did not it would have perverse consequences. I am just saying it has not been explicitly tested at the elementary particle level.Vanadium 50 said:Of course the same is true for a grain of rice. Nobody doubts that rice gravitates.
mjordan2nd said:Is there any experimental evidence that pure energy (massless) can curve spacetime?
Orodruin said:I do not doubt that light gravitates.
Vanadium 50 said:Are you using it to mean "is a source of gravity"?
That was the first time I used the word gravitate. Since the OP is directly asking about the influence of massless particles on the curvature of space time, I do not see how my posts can be interpreted as being about the influence of the space time geometry on the particles.Vanadium 50 said:I think we are using the term "gravitate" differently. I am using it to mean "is affected by gravity". Are you using it to mean "is a source of gravity"?
Well, that's reasoning the other way around: we measure the expansion of the universe, and we postulate that some form of energy is the source for this expansion, namely the cosmological constant.ebos said:Dark energy seems to be doing a good job of expanding the universe and everything in it. Does that not count?
I don't know what you mean by "gravitational charge". If you mean the source of gravitational fields (in the same sense as charge-current densities are the source of the electromagnetic field) then your statement is wrong, since as Einstein's field equations tell you, the source of the gravitational field are the energy-momentum-stress distributions of matter (including radiation!), universally coupling to the gravitational field.Ibix said:So - if only massive particles produced spacetime curvature then "gravitational charge" would depend on nucleon number (or very very nearly so) not mass. Thus the Eotvos experiments would not have the outcome they did.
...right?
mjordan2nd said:Is there any experimental evidence that pure energy (massless) can curve spacetime?
Pure energy, also known as vacuum energy or zero-point energy, refers to the lowest possible energy that a quantum mechanical physical system may have. It is the energy that remains in a vacuum even at absolute zero temperature.
According to Einstein's theory of general relativity, mass and energy are equivalent and can bend the fabric of spacetime. This means that the presence of pure energy can also cause a curvature in spacetime, just like mass does.
Yes, pure energy has been observed in various experiments, such as the Casimir effect and the Lamb shift. However, its effects on spacetime curvature are still being studied and require advanced technology to detect.
Scientists use highly sensitive instruments, such as interferometers, to measure the minute changes in the fabric of spacetime caused by the presence of pure energy. They also conduct experiments in vacuum chambers to eliminate any interference from external factors.
According to current theories, there is no limit to how much spacetime can be curved by pure energy. However, the amount of curvature is directly proportional to the amount of pure energy present. Therefore, the effects of pure energy on spacetime may be limited by the amount of energy available.