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Comment by quickthrower2 | Hacker News Reader

Want to know more about that cosmic explosion. If it does this 2bn ly away, what would it be like for anyone within say a million ly?

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> The worst-case scenario would be if such a powerful blast came from much closer to home—say, within our own Milky Way galaxy. That could "completely erase" Earth's ozone layer, he said.

The diameter of the Milky Way is 100,000 light years. 1 million is 100 times less powerful but it definitely wouldn't be fun.

So could you say that when we see such a gamma ray burst in a distant galaxy (which apparently occurs daily from our point of view), that's witnessing all life in that galaxy being wiped out?

This is pretty horrifying :/

Would such a burst travel through the body of a planet? If not, perhaps only half of the galaxy’s life would be wiped out.

Absolutely, as if it was basically not there.

Surely the Earth would be too thick for that?

We're dealing with incomprehensible amounts of energy. GRBs are powered by the violent deaths of massive stars. Orbiting planets are inconsequential.

Have a fun paper!

Stars Bisected by Relativistic Blades

https://arxiv.org/abs/2309.15347

I thought only neutrinos could do this?

It doesn't happen daily, does it? This one was a one in several thousand years event.

There are 100-200 billion galaxies in the observable universe. It may well be daily when you do the math.

A GRBs is observed around daily according to Wikipedia.

The one here was a one in a thousand year in brightness, but that might have been due to being closer to us?

As I understand it GRBs are highly directional because the magnetic fields involved in the explosion for us energy into narrow beams. We see the events as GRBs when we cross through the path of the beam. When we see the same type of supernova from the side we still see a bright burst but not nearly as bright as as GRB. If a supernova goes off in your stellar neighborhood you might be screwed if you're in the beam of the GRB or just mildly inconvenienced (minor mass extinction) if you get a side view.

So the events causing GRBs are slightly less horrifying than galaxy-sterilizing monsters.

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