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I wish they would forget about mars........


spurius

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The main problem with that is, assuming that E=mc2 is correct means that light, or photons, don't have any energy, which is incorrect (otherwise the Sun wouldn't be able to heat the Earth etc.), and if photons do not have mass, then black holes wouldn't be able to trap them.

E=mc2 is actually an approximation, so you need to be careful what inferences you make using it -- the terms that are left out may be meaningful. I think the remaining terms relate to momentum which might not appear to be relevant when talking about light, but I'm not entirely sure that's the full story.

However, is it even right to say that black holes couldn't trap photons if they didn't have mass? Or is the distortion of space-time caused by the black hole sufficient?

James

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I've just been reading the story of Australian explorer Douglas Mawson in the January issue of National Geographic. He led an expedition of 31 men into Antarctica in 1912 and not all of them returned.

What drives these people is beyond any level of motivation I've ever experienced. Mad I'd say!

But it makes gripping reading even in a short article.

Just imagine if such men could now get hold of the technology to escape the clutches of Earth. Hell, Pluto would have a McDonald's on it by now !!!

What are we waiting for??

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E=mc2 is actually an approximation, so you need to be careful what inferences you make using it -- the terms that are left out may be meaningful. I think the remaining terms relate to momentum which might not appear to be relevant when talking about light, but I'm not entirely sure that's the full story.

However, is it even right to say that black holes couldn't trap photons if they didn't have mass? Or is the distortion of space-time caused by the black hole sufficient?

James

This is why I want to do a degree in Physics or Astrophysics :angel:.

I did know E = mc2 isn't the whole story, but I haven't really read enough up on General Relativity.. I know a bit of Special Relativity, but only a bit.

I do realize we've strayed very far from the original post. Sorry to the OP.

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The main problem with that is, assuming that E=mc2 is correct means that light, or photons, don't have any energy, which is incorrect (otherwise the Sun wouldn't be able to heat the Earth etc.), and if photons do not have mass, then black holes wouldn't be able to trap them.

This video explains gravity:

You don't find out until the very end but the reason why black holes trap light is because they are energetic. Gravity doesn't attract things that have mass, but rather objects that are energetic.

Josh

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You don't find out until the very end but the reason why black holes trap light is because they are energetic. Gravity doesn't attract things that have mass, but rather objects that are energetic.

And that's why, if you don't burn off all of those calories you eat by exercising, gravity has a bigger effect on you.

James

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