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Layman here, but EE and BS physics. I know that light is affected by gravity. But are neutrinos? During the collapse of a star into a neutron star, as the electrons join protons to form neutrons (e.g., or the collapse of a star to a black hole?), I read that the only things that can get "out" instantaneously are the neutrinos. (this even applies to a normal star I presume, as the photons take "forever" to exit). But I know gravity is extreme in these instances, to say the least, so does gravity NOT affect the neutrinos? This would seem to be contradictory.

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Related: – Qmechanic Apr 17 '12 at 11:29
There are good answers below (particular @LeosOndra); but I wanted to add that everything is effected by gravity, according to general relativity. Because gravity is a distortion in space-time itself, it doesn't matter what the properties of the particle/object is. – DilithiumMatrix Apr 17 '12 at 13:00

Neutrinos are certainly affected by gravity. However extreme gravity may be around the collapsing core of a massive star, the real problem is great density of matter. Neutrinos interact with the stellar matter much less than other particles so they escape much easier, though the very center of the collapsing core is opaque even to them.

In fact, the main problem of the supernova-to-be massive star is not where to get energy (it is at hand in the form of potential gravitational energy) but how to get rid of it! Energy must be carried away from the core to enable collapse - and it is carried away by the neutrinos.

However, even neutrinos don't escape from the collapsing star instantaneously. About 1 per cent of their energy is absorbed in outer layers, reversing their collapse to explosion - the visible firework of the supernova. The rest (99 per cent !) of the original gravitational energy is quietly carried away by neutrinos.

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The main question is best answered by the linked question, but the neutron star part of this question is another matter.

Common particles that try to escape a neutron star find themselves hindered not by just gravity, but also by the electroweak force. And with the density of neutron stars, the latter is very strong too. Neutrinos aren't so affected by electroweak forces, which is why they "instantaneously" escape neutron stars.

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