Betelgeuse, Betelgeuse, Betelgeuse... may be getting closer to Supernova...

What I'd like to know is simple;

In the event Mother Earth gets swept by a gamma ray burst, in the
reference frame where I'm at, will I get any warning as to when I should
bend over and kiss my a$$ goodbye? :target:

 

That's the untold beauty of many disaster scenarios - you'll never know what hit you, so there's no point worrying about it.

 

Yeah. The trouble with a photon is it's both a wave and a particle, so it's sort of hard to talk about its "size" other than wavelength. Although, of course, wavelength does contract or expand with motion along the line of sight. However, this is fundamentally different from Lorentz contraction, where I believe that contraction (and not expansion) is the only thing that can happen.

Ah! I see our point of disagreement, I think. The space the photon had to travel didn't contract to zero. The photon's size would have contracted to zero if the photon had a size. But, spacetime is not an object, so spacetime doesn't contract in that way.

Absolutely; you're accelerated with your watch, but that doesn't change the fact that time appears to pass normally for you (or your photon). Einstein showed that gravitational effects are equivalent to acceleration effects by the so-called "Equivalence Principle."

It's also worth saying that these relativistic effects start to matter well before you get to the event horizon, so you could have some of these effects and escape to tell about it. Of course, if you spend too much time (ha ha) in the time-dilated regions, all of humanity may be gone by the time you emerge.

Heh. My favorite thing to tell people about falling into black holes is about spaghettification. There are huge tidal forces as you approach a black hole because the gravitational pull on the part of you closest to the object is much greater than on the part of you furthest away from the object. Hence, you're stretched like a piece of spaghetti.

Again, you're casting this as a "length contraction" argument when I think it's a "time dilation" argument. From Earth, it will appear that you are traveling at, say 200,000 km/s, then it will take you 1 second to traverse 200,000 km from the point of view of Earth. However, from your own point of view on the rocket ship, it will only take 0.75s, but this is because of time dilation and not because of length contraction.

Yup. This is the "speed of light is constant in all frames" argument.

 

Nope.

On the other hand, if the Earth is demolished by a large asteroid, there's a very small chance they might see it coming. Whether they would make an announcement and throw the world into total panic for its last few hours is another question.

The astronomers might have already sighted it, and determined that it will hit Peoria, IL, at 2:17 a.m. tomorrow morning, Central Time, leaving nothing but smithereens where the Earth was, and decided there's no point in telling us.

Let's say they knew the Earth would be pulverized a week from tomorrow and there was nothing anybody could do to prevent it. Would you rather they announce it so that people would riot and rampage and rape and murder, knowing that it didn't matter any more? Or would you rather they kept it secret so things would go along normally until the end?

 

What's normal? And why would it not matter, just because there'd be no punishment? Wouldn't doing bad things still be wrong? Not that I'm saying I wouldn't change my behaviour, knowing the end is nigh, though if I always lived life like there was no tomorrow, I wouldn't be very productive.

 

OK, in the event of a sufficiently large asteroid, I understand that the
Earth would be essentially vaporized... or perhaps dustified.

And as a result, each one of us would take our place in the cosmic order
in a widely dispersed molecular condition.

But back to the gamma ray burst... Would the gamma rays penetrate
extremely deep into the soil, rocks, water, concrete, etc, and kill nearly
every living thing on earth? (I suppose there's some hope for a rare
virus, or bacteria, or maybe the cockroach.)

Or is it remotely possible that folks who on that fateful day find
themselves deep underground or underwater might survive...
for a while at least... if the burst is relatively short-lived.

 

Would you continue going to work, knowing that you'd be dead before your next paycheck? Do you suppose truckers would continue to bring food to stores and fuel to gas stations, or that electrical workers would continue to keep the grid operating? What percentage of the population would have to go berserk before law and order would collapse, and would the police even bother to try to maintain order, knowing that they, too, would be dead before their next paycheck, or would they stay home to protect their own families from rioters?

Small communities might stick together, but some number of disaffected city dwellers would likely decide that coveting their neighbor's wife or daughter was not as satisfying as killing their neighbor and taking his wife or daughter.

Would military units move in, or would the commanders, too, decide that there was no point?

I do think there would be chaos, rioting, rape and murder, if everyone knew that the Earth was about to be obliterated. I think most people would not do this. But I think enough people would that those last few hours or days would be far nastier than if the information were kept secret.

Then also there would be the religious nut jobs who would decide this was god's final punishment, and they would go around killing everyone they regarded as an infidel, in the hopes of garnering god's favor.

I don't know the answer to this. I was saying (in answer to what I thought was your question) that the gamma ray burst itself would be the first indication that the star had blown.

My impression is that creatures under the sea would not be immediately affected, and especially, those weird things at deep-sea vents would be entirely unaffected. But I imagine that if the surface were sterilized and the ozone layer removed, the surface of the earth would become uninhabitable and any underground or underwater artificial environment would be a nasty place to live.

I don't know how long a gamma ray burst would last, but I imagine our astronomer friend could tell us.

 

No, but neither would I be out raping and pillaging. More likely I'd be defending the family. So, yes, probably better that not everyone know.

As for what would survive this hypothetical cataclysmic event, I'm not sure. But something would - there've been mass extinctions before, and there will be again. It reminds me of Einstein's assertion that "God does not play dice with the universe". Disregarding his cosmological constant, I'd say Life does indeed take chances. But it takes so many chances that something is guaranteed to survive, no matter what.

 

I understand most gamma ray bursts to last a few seconds. It could immediately sterilize only the surface of the half the planet facing it. Not sure how deep the rays would reach. The other half of the planet would be untouched by the GRB, but the loss of half the planet's ozone and other disruptions will have severe side effects for nearly all life forms.

Any asteroid large enough to vaporize or dustify the earth should be seen a very long way off, with plenty of warning. Civilization-destroying asteroids can be far smaller, giving much less warning, and the search for them is quite active. For daily updates, look down the page of SpaceWeather for the 'Near-Earth Asteroids' section.

 

Life will survive. We might not. I care mostly about whether I survive.

Einstein said "god does not play dice" as a reply to quantum theory when it was new. Quantum mechanics is all about probability, and Einstein thought that could not be true. He later retracted his statement, and called it the biggest mistake of his scientific career.

(Note: He said this also of the cosmological constant. Apparently he regarded different things at different times as his "greatest" mistake. But nonetheless, he acknowledged that the bit about god not playing dice was a real whopper. God, if there is a god, does indeed play dice. And why shouldn't he if he chooses? If there is a god, he is not required to be as Kow or the Pope thinks he is or should be.)

"God made the world in six days flat.
On the seventh he said, 'I'll rest.'
Then he let the thing into orbit swing
To give a dry-run test.
A billion years went by then he
Took a look at the whirling blob.
His spirits fell as he shrugged, 'Ah, well.
It was only a six-day job.' "
-- Unknown

A kid makes a sand castle on the beach, doesn't like it, and stomps on it. If there is a god, he might decide to stomp on this particular sand castle. An asteroid would work pretty well.

Fortunately, I don't believe the FSM cares enough to bother stomping on us. Unfortunately, I don't believe he cares enough to deflect an asteroid that happens to come our way, either.

 

Re: Betelgeuse... I was hoping you were gonna show up Bra... I'm glad you did.

 

Ok, so the odds of surviving the gamma ray "impact" is ~50/50.

I wonder what the odds would be for surviving one year...

Ten years?