"Armageddon" Cosmic Events

[Kitsune]

I was watching a show about extinction events a while back and there was a suggestion of some type of cosmic event which could take out all life in a solar systems or even all solar systems for hundreds if not thousands of light years.

I cannot remember it real well so I am kind of hoping that somebody might know what kind of events might cause something like that?

[Erik von Nein]

Giant gamma beams being blasted from pulsar stars? That's a pretty fun one. Wouldn't even see it coming, either. That's the best part.

[Kitsune]

What type of range does that actually potentially have according to most calculations and do you know any links on it?

[Shinova]

I think the range is in thousands of lightyears, and still means pretty much instant death of all life on Earth at that range.

[Kanastrous]

Assuming more-or-less perfect alignment between the Earth and the radiation source.

[Kitsune]

How wide a "Cone" might this beam have?

[Lord of the Abyss]

Another example wopuld be something like the 'Death Star galaxy', whose central black hole is producing a jet that's striking another galaxy.

[Erik von Nein]

How wide a "Cone" might this beam have?

Pretty large. This might help with understanding what could happen to Earth if a gamma ray burst hit: http://www.pbs.org/wgbh/nova/gamma/milkyway.html

[Sriad]

A couple others: a Type II supernova (the "normal" kind) could sterilize planets within a couple hundred light-years.

A binary pair of neutron stars coalescing into a black hole would throw out a bowel-liquefying quantity of hard radiation on the plane of their orbit. (bowel-liquefying is a scientific term that equates to roughly 5.232e47 joules: the mass of 2 average neutron stars 45% converted to energy in accordance to what we know about black hole accretion. This is the same magnitude as extreme high-intensity/short duration gamma ray bursts; degenerate object coalescence is one of several events that could produce such GRB.)

[starslayer]

A couple others: a Type II supernova (the "normal" kind) could sterilize planets within a couple hundred light-years.

Not so. Life could actually easily withstand a supernova out past about 50 light years without difficulty. That neato inverse-square law for irradiance really saves our asses sooner than you might think.

How wide a "Cone" might this beam have?

Quite large, as Erik says. Even assuming the beam were generated as by a graser, the beam spread over even a few light years is great enough to easily be much, much wider than the Earth and possibly even the Solar System. Given the distances involved for even the closest possible burster, and also the fact that the jets (the jets are what produce the GRB as they slam into the ISM and other material, along with the influx of matter into the newly formed black hole) are most certainly not focused nearly as well as a laser, the beam when it reached Earth would be far wider than the inner Kuiper Belt. And the beams are still powerful enough to cause major damage.

As to the OP, pretty much the only candidates I can think of are supernovae and GRBs. Both, if you are close enough, put out more than enough energy to wipe planets bare, and even vaporize their crusts (this is Really Fucking Close, though).

[Kitsune]

The reason why I am asking is that I want to create a stellar "empire" which was destroyed which has various artifacts which can be potential discoveries. Trying to see a plausible way with FTL that a death blow would be inflicted by some sort of cosmic event

[Lord of the Abyss]

The reason why I am asking is that I want to create a stellar "empire" which was destroyed which has various artifacts which can be potential discoveries. Trying to see a plausible way with FTL that a death blow would be inflicted by some sort of cosmic event

Here's one way to do it, ( with an idea from the obscure old Antares trilogy ). Use a version of FTL that uses wormholes, folded space, whatever you want to call it that's affected by such things as stellar masses. A star goes supernova - and the sudden dispersal of so much mass changes or shuts down the FTL routes. Either their FTL no longer works, or doesn't lead anywhere that's a safe range from the star, and they fry. Later, changing stellar positions ( or some other astronomical event ) opens a new route and people can reach the dead empire. In the trilogy the likelihood of such disasters was increased because the larger the star, the more "foldpoints" it tended to have, which meant that trade routes tended to go through and cluster around the stars most likely to supernova.

[Erik von Nein]

I can't image any realistic event that could effectively kill of an entire stellar empire. Once you've reached multiple planets the likelihood of any one event destroying your civilization completely is pretty minimal, especially with FTL travel. I'd imagine they'd have mapped and be monitoring all potential dangerous stellar activity in the region and have planned accordingly. The reason why GRB or the like are so dangerous to us is because of two reasons; first we live on only a single planet with no means of reaching other systems and second is that we STL ways of monitoring our universe.

Even if you potential civilization didn't have FTL monitoring devices, they could just post something that has FTL near the body and watch it, then travel to what ever planet it could affect and just evacuate people. Or, at least, the most important parts. It'd take a really long time before any phenomenon came close to destroying any planet in the way.

At that these phenomenons would only affect one or two planets or systems (barring the aforemention "Death Star" galaxy which would just kill everything). Even Lord of the Abyss's idea doesn't really work very well. A star going nova is pretty obvious and takes forever, so I'd imagine they'd plan to move their routes before that happened.

[Icehawk]

So from what I've gathered, if there was a large gamma burst withing a few thousand light years, the radiation just be enough to blast away the ozone layer? Or would it be powerful enough to actually strike us on the ground and cause mass populations of people to all suddenly suffer deaths of the likes of Louis Slotin or Harry K. Daghlian did from getting hit with a massive burst of radiation? That would be truely horrifying, getting up one day and suddenly realizing you and then EVERYONE around you are rotting away from a massive burst of radiation.

[CaptainChewbacca]

The only thing that can wipe out a stellar empire would be if a star in the middle of it went Nova, or if a rogue black hole whipped through the plane of the galaxy at high speed.

So from what I've gathered, if there was a large gamma burst withing a few thousand light years, the radiation just be enough to blast away the ozone layer? Or would it be powerful enough to actually strike us on the ground and cause mass populations of people to all suddenly suffer deaths of the likes of Louis Slotin or Harry K. Daghlian did from getting hit with a massive burst of radiation? That would be truely horrifying, getting up one day and suddenly realizing you and then EVERYONE around you are rotting away from a massive burst of radiation.

For a GRB to actually 'fry' a planet, it would have to be less than 500 light years away. Further out, it would destroy ozone and give everyone a good sunburn. Stuff underground or that remained indoors could survive, but a GRB leaves a persistent 'field' of radiation for a few weeks afterwards.

And yes, a GRB can encompass an entire solar system, and propagates at a good fraction of c (though not at c).

[Kitsune]

I think there is a reasonable explanation.....the FTL is gravity base based on the Universe and near gravity holes, the FTL cannot be used. Simply that there is some of of gravity flux which preceded the Armageddon event.

[starslayer]

For a GRB to actually 'fry' a planet, it would have to be less than 500 light years away. Further out, it would destroy ozone and give everyone a good sunburn. Stuff underground or that remained indoors could survive, but a GRB leaves a persistent 'field' of radiation for a few weeks afterwards.

And yes, a GRB can encompass an entire solar system, and propagates at a good fraction of c (though not at c).

A GRB propagates at c. It stands for "gamma ray burst," after all, and gamma rays are EM radiation, and thus always move at c. And no, a GRB doesn't leave any fallout. It's a one-time shot of radiation that, unless it's extremely close, doesn't penetrate the atmosphere, merely totally fucks up atmospheric chemistry. But yes, you could survive by heading underground for the few months to years it takes for the ozone layer to reform, and the smog to dissipate.

[Ryan Thunder]

For a GRB to actually 'fry' a planet, it would have to be less than 500 light years away. Further out, it would destroy ozone and give everyone a good sunburn. Stuff underground or that remained indoors could survive, but a GRB leaves a persistent 'field' of radiation for a few weeks afterwards.

And yes, a GRB can encompass an entire solar system, and propagates at a good fraction of c (though not at c).

A GRB propagates at c. It stands for "gamma ray burst," after all, and gamma rays are EM radiation, and thus always move at c. And no, a GRB doesn't leave any fallout. It's a one-time shot of radiation that, unless it's extremely close, doesn't penetrate the atmosphere, merely totally fucks up atmospheric chemistry. But yes, you could survive by heading underground for the few months to years it takes for the ozone layer to reform, and the smog to dissipate.

There would be 'smog' from a GRB?

Or was that figurative? <_<

[Erik von Nein]

I think there is a reasonable explanation.....the FTL is gravity base based on the Universe and near gravity holes, the FTL cannot be used. Simply that there is some of of gravity flux which preceded the Armageddon event.

Uh, what? Did you mean gravity wells?

In any event, sure, you could make up something that prevents some people from leaving a planet long enough to kill most of them (though, they should have some protection against these kind of events) but, even if most of them died the rest of the empire would live on. It could descend into chaos, but I still don't see how they'd get regulated into obscurity.

[Covenant]

You could always have the galactic civilization wiped out when it and another small galaxy collide and combine. There's nothing more overtly destructive to the order of a galaxy than being thrown around and torn apart by being impacted by another body of roughly the same size. Plus, this would leave relics scattered all over the fucking place.

[Ariphaos]

You could always have the galactic civilization wiped out when it and another small galaxy collide and combine. There's nothing more overtly destructive to the order of a galaxy than being thrown around and torn apart by being impacted by another body of roughly the same size. Plus, this would leave relics scattered all over the fucking place.

In a universe with FTL? Please tell me you're joking. Collisions take hundreds of millions of years, and few if any stellar collisions occur.

Something I've been wrestling with in Solar Storms is the nature of energy-releasing tachyons. Since they are nonlocal, and all of their energy gets released at the same instant in some preferred frame, if you have a dimensional tap and the radius of a burst is sufficiently large (a few kiloparsecs, say), a good portion of everything within the burst's range is doomed to die a slow heat death, as if it were a part of a significantly less intense Big Bang.

[CaptainChewbacca]

A GRB propagates at c. It stands for "gamma ray burst," after all, and gamma rays are EM radiation, and thus always move at c.

I'm sorry, but you are incorrect. For a book I'm writing, I am using GRB's as a 'plot mover', and so I contacted Dr. Edo Berger, one of the world's foremost experts on the phenomenon. His response to my questions about the speed of GRB's:

The GRB starts off with a Lorentz factor of about 300-1000 (i.e. as close to c as any astrophysical source gets, other than light; about 0.999999c). It then slows down to Lorentz factor of about 10 (i.e. 0.99c) after a day, and eventually slows down so that the speed is much less than c after several months and continues to coast at this "slow" speed for many years. After thousands of years it will eventually be fully stopped by interaction with gas within the galaxy.

GRB's may start out at near-c velocities, but they do slow down.

And no, a GRB doesn't leave any fallout. It's a one-time shot of radiation that, unless it's extremely close, doesn't penetrate the atmosphere, merely totally fucks up atmospheric chemistry. But yes, you could survive by heading underground for the few months to years it takes for the ozone layer to reform, and the smog to dissipate.

The wavefront of a GRB is not an instantaneous passing, and can actually take hours or days to completely move across a given planet. Keep in mind, X-rays are also a significant portion of the energy of a GRB, and may penetrate more deeply than gamma. A GRB originating 10k light years from a world is still strong enough to cause an Extinction Level Event when it strikes the planet.

[Kodiak]

The wavefront of a GRB is not an instantaneous passing, and can actually take hours or days to completely move across a given planet. Keep in mind, X-rays are also a significant portion of the energy of a GRB, and may penetrate more deeply than gamma. A GRB originating 10k light years from a world is still strong enough to cause an Extinction Level Event when it strikes the planet.

I guess it's kinda like a water pipe blowing a leak: High pressure, narrow field at the outset, then slowing and spreading as it travels. Would a GRB be subject to conservation of momentum? If so, that makes a lot of sense in my understanding.

[Wyrm]

I'm sorry, but you are incorrect. For a book I'm writing, I am using GRB's as a 'plot mover', and so I contacted Dr. Edo Berger, one of the world's foremost experts on the phenomenon. His response to my questions about the speed of GRB's:

<kersnippy>

The wavefront of a GRB is not an instantaneous passing, and can actually take hours or days to completely move across a given planet. Keep in mind, X-rays are also a significant portion of the energy of a GRB, and may penetrate more deeply than gamma. A GRB originating 10k light years from a world is still strong enough to cause an Extinction Level Event when it strikes the planet.

I take it you're talking about the actual matter of the GRB event, rather than the gamma-ray radiation, here. That would make your post make sense.

I guess it's kinda like a water pipe blowing a leak: High pressure, narrow field at the outset, then slowing and spreading as it travels. Would a GRB be subject to conservation of momentum? If so, that makes a lot of sense in my understanding.

Of course a GRB is subject to conservation of momentum, you bozo, just like everything else in this universe. At a few kpc, however, the actual impulse delivered will be very small.

[Lord of the Abyss]

Here's a thought. Perhaps the disaster is something really large, like massive activity from the galaxy's central black hole. Something massive falls in ( perhaps another supermassive black hole, left over from an ancient galactic collision ), and your peaceful, life bearing galaxy turns into a radiation filled active galaxy, at least until whatever is feeding the hole runs out. Or perhaps the galaxy is being hit by something like the previously mentioned "Death Star" galaxy.

Further; assume that there are at least two forms or modes of FTL; the normal kind that is typically used for interstellar travel. And, a far more expensive kind that can jump between galaxies. In that situation, a relatively few refugees, probably the richest/most powerful, could escape to another galaxy ( and thus giving a source for any legends of a lost empire ), while the vast majority can't run far enough. Especially if the normal form of FTL is a "wormhole" style between stars. The refugees no longer have the resources to jump back, even if the disaster dies down during their lifetimes. Which is unlikely considering the scale we are talking about here.