I have heard that these would kill all life on Earth. What if someone is far underground, say working in a mine when it hits? Would they survive? How about submarine crews?
Here’s a handy chart for some sample halving distances of different materials.
3 feet of packed earth is considered good enough protection for a nuclear weapon. Something like 6 feet of water affords the same protection.
But note that not all radiation is blocked. Some will get thru. You are just cutting down the percentage.
You’d have to calculate the maximum theoretical intensity of a likely nearby gamma burst (e.g., the Sun and closest stars aren’t going to be a problem). Etc.
But as to your examples: any reasonable mine or submarine well under the surface is fine.
We survive gamma ray bursts all the time. But they are billions of light years away. Within 500 light years? No, we wouldn’t survive. Everything would be dead except in the deep sea and deep underground and that would die pretty quickly too.
One side of the planet will be shielded by the entire earth. For some intensity of gamma ray burst, the shielded half will be fine but the exposed half will be fried. Of course, there may be indirect ecological effects that cause a completely global catastrophe. I don’t know if the GRB itself would, say, set continents on fire, but continent-scale wildfires would eventually follow as entire dead ecosystems dry up and turn to tinder.
I saw something on TV once about a proposal to construct an underground repository of our species’ genetic material in the event of a gamma ray burst. I think the idea was that some space-faring species would stumble across it later and reconstruct us à la Jurassic Park, but I’m not sure. I can’t really remember what I was watching or what the entire gist of the argument was. I think they also mentioned that the ocean on the lit up side of the Earth would boil off, so being in a submarine may not be too pleasant an experience. Better off being on land where you would fry to a crisp in two nanoseconds flat. They mentioned something about the Earth’s crust being liquefied, but how far down is open to conjecture.
The heat of it in the atmosphere on the hot side would still roast the shadow side. Getting hit by one cosmic ray can have the energy of a major league bean ball. Flooding the atmosphere with zillions will roast everything that isn’t very deep down.
Forgive my obtuseness, and my indolence in not pursuing the question via Google, but how does that work ?
Does a gamma ray burst lose intensity as it travels through the universe?
Distance is everything. Also the fact that GRBs are “beamed” from the rotational poles of the progenitor. If the beamed jet is directly pointed at us AND the progenitor is close enough (maybe a few hundred lightyears), there might be a global catastrophe. Earth need not be fried - enough disruptions to the climate could kill us all indirectly.
Everything loses intensity with distance. Each individual gamma ray still has just as much energy, but there’s a difference between being hit by one gamma ray, even an extremely energetic one, and being hit by zillions of them. One gamma ray, worst case, it might give you cancer years later (or might not: The most probably outcome is that it’d just zip right through you and not do anything to you at all). Enough of them, though, will cook or even vaporize you.
The Second Stone, while it’s true that an individual cosmic ray can pack the same energy as a fastball, those are protons, not photons. Cosmic rays that energetic are also extremely rare, and of unknown origin. You won’t get anything quite that potent from a GRB.
With the exception, of course, of enchantment …
I think I have figured out how it works … it’s similar to a shotgun blast, right ?
If your ass is 1" away from the muzzle, when the trigger is pulled, you have a problem … if you are are 100 yards away you might get a slight peppering of the buttocks, but probably not fatal., the pellets disperse the further they travel.
So these gamma ray bursts travel out like in a conical formation, and the density of the rays diminishes the further they travel, although the actual energy of each ray is constant.
Have I got that right ?
Yeah, that’s basically it. Except that with a shotgun, the individual pellets will lose energy with distance, while the gamma rays won’t.
Well damn, what’s the point of an ultra intense gamma ray burst Earth extinction party if we can’t invite the mysterious highly energetic ‘cosmic’ rays too. I’m sure Professor Proton would come to the party. 'cept he died. Sniff.
Like that ever stops a comic book character.
Philip Plait aka The Bad Astronomer is a blogger at Slate and was formerly a prolific poster at this very message board. His book Death from the Skies covers gamma ray bursts. The book is recommended as an introduction to recent developments in astronomy as seen through the lens of The End of The World As We Know It and other sorts of mayhem.
Anyway Dr. Plait is more concerned with asteroid impacts than he is about gamma ray bursts. “I studied gamma-ray bursts for many years, and I personally am not at all worried about them.” Solar flares are also a reason for concern.
A population in a shelter protected by 100 metres of rock would suffer very few ill effects from a gamma-ray burst, even a relatively nearby one… The problem would be when they emerge into a biosphere that gas been comprehensively blasted by gamma rays. The atmosphere would be full of nitrous oxides for days or weeks - these would rain out fairly quickly, but not before the NOX removes much of the ozone layer - an effect that would last many years.
Radiation damage to land plants and animals would be severe - but sea plankton should be protected somewhat by the water. And of course NOX is toxic. So if the gamma ray burst were very close, the biosphere would be in no shape to support the survivors. They will need at least a few years-worth of food supplies in storage to tide them over before they start growing food again.
What would be the duration of such a blast?
Hours?
Seconds?
Centuries?
It makes a certain difference.
Ultra-long GRBs last in excess of 10,000 seconds.
that’s about three hours.
The vast majority are a few seconds or shorter, though.
You neglected to do a pun on “noxious”. Shame on you.
Plait is correct to be more concerned about asteroid and cometary impacts as well as solar storms resulting from coronal mass ejections (CME) e.g. a “Carrington”-type event rather than extra-solar gamma ray bursts, not only because they are statistically more likely but also because there are practical measures we can take to protect ourselves from the effects of those types of threats, whereas there is essentially nothing to be done to protect the Earth from an unlikely but intense GRB. A GRB would not only “burn” the lower atmosphere producing a number of noxious byproducts and kill any complex life on the exposed facing surface, but would also strip away the protective ozone layer, exposing the surface to lethal levels of ultraviolet radiation (UV) from solar sources. Regardless of protection from the initial event, extinction of any but the most hardy species would be eradicated.
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