# OPTICS and GRAVITY

Discussion in 'Astronomy, Exobiology, & Cosmology' started by hansda, Sep 9, 2012.

1. ### hansdaValued Senior Member

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Consider a hypothetical case that, mass of 100 kilos is travelling past the Sun at the velocity c. What would be its curvature? Same as photon or more?

3. ### OnlyMeValued Senior Member

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Assuming that the mass has inertia and is passing the sun, and that the photon having no mass has no inertia.., the mass would be deflected less than the photon.

The inertia of 100 kilos moving at c would exceed the escape velocity of the sun at any distance. Even striking the sun it would likely result in a significant "chunk" of the sun, being knocked off or away from the sun.

This is the point I was trying to make with the neutrino. It is not the near c velocity alone that results in a space-time path near that of light. It is the fact that the mass of the neutrino is so small and it's velocity near c. A larger mass with a similar velocity would follow a different path.

As soon as you add mass and velocity you create the potential that the object's inertia will represent a "force" opposing gravity and the effect of the curvature of space-time. Again the only reason the neutrino appears to follow a similar path through spacetime as light is that its mass if insignificant and it's velocity is near c.

5. ### hansdaValued Senior Member

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How? If deflection of photon is 4M/R, you mean to say deflection of the mass will be less than 4M/R?

How escape velocity is coming into the picture if the mass follows a trajectory grazing the Sun like the gravitational lensing for starlight around the Sun.

"A larger mass with a similar velocity would follow a different path." - that is right but what would be the relation of deflection with its mass?

What do you mean?
So you are considering mass of particle Neutrino is insignificant ie not affected by gravity.

7. ### hansdaValued Senior Member

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If a massless particle can be kept at rest within a gravity well, will the massless particle fall into the gravity well?

8. ### OnlyMeValued Senior Member

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Since there are no known massless particles that exist at rest, even relative rest, the question has no answer. I am not a particle physicist, but I am pretty sure all know massless particles have a velocity of c.

9. ### hansdaValued Senior Member

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Massive particles also does not exist at rest.

The answer to my question should be either 'yes' or 'no'.

Earlier you told about experimental results for some atomic particles. So results for massless particles also can be predicted to some extent.

We know massless particles follow curvature of spacetime but whether a 'massless rest particle' will fall into the gravity well or not; that is to be decided.