I'm curious, what's the speed of a supernova or some other major disaster that can happen in the universe? I'm just wondering because I was browsing through some topics in another folder and there was mention of when the world was ending.

As you all know, when we look out into space, we're basically looking into the past because light beams are barely catching up with us. And using the common date of the world ending in 2012, if for some reason, we were able to look into the future (which is actually the present) elsewhere in the universe or if someone from the other side of the universe came and warned us of the impending disaster of the supernova (or other disaster) catching up to us in 2012 (much-like how other countries instantly got word by phone of the SE Asia tsunami coming once other countries were hit), would we be able to find out where the disaster originated from?

So let's take the year 1000 AD, or whenever the Mayans figured out the world would end (assuming that's what happens), that would mean whatever the disaster in outer space was, it would take 1012 years to finally reach us. Now if we know the various speeds of disasters such as super novas (assuming it's possible to know), how far away from us would that point of disaster have occurred (from whichever direction it is)? Would that be super far or pretty close where our current telescopes can view? Again, I have no idea as I don't know the speeds of those disasters as I'm a n00b at all this, heh. Thanks though.

- N

The world isn't going to end in 2012; the date is simply when the ancient Mayan calendar runs out. Like all other calendars it will start again with day 1 the next day.

Incidentally the gamma and x-ray blast would travel at the speed of light, so no warning of an exploding supernova would be possible. Mayans of course did not have telescopes, nor any science of astrophysics; today we do have such a science, and by studying the states of nearby stars we can be pretty much certain that no nearby star is going to go supernova in 2012.

Oh, I know, I doubt the world will end in 2012, I was just using that as an example of us somehow having an advanced warning of something happening on the other side of the galaxy (assuming it were true, etc). I was more interested in the whole "what we see is the past" aspect of it all and how we have no idea what's happening or what's recently happened in the other side of the galaxy, and if we somehow had some advanced warning of an event happening 1000 years from now, we'd be somehow reading the future, even though there's not really a such thing as time, it's just a measurement.

I used the example of 2012 and us hearing about it 1000+ years before just to see if a scenario were possible, how far away would it have to have occurred (which I just noticed and get a big "duh" award as it would be 1000 light years away since as you mentioned, those rays travel at the speed of light, heh) in the galaxy to finally reach us in that many years. Can we even see 1000+ light years into the past with our current telescopes? If not, what's the farthest we've seen? And if it takes 1000+ years for some event to reach us from that far away, would there even be any power left in the supernova, or other event, to do any harm so as to somehow kill us off. What's the most powerful universal disaster possible? Is there anything that has the power to do damage within a 1000 light year radius?

- N

I think I read some where that we would be safe from an ordinary nova more than 20 light years away, but a Nova in the Centauri system would wipe us out.

I would not bet much money on this particluar memory. The Centauri part of it seems right, but perhaps 20 light years is too close for safety.