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The Milky Way's Most Recent Supernova That Nobody Saw
StartsWithABang writes: A little over 300 years ago, a supernova — a dying, ultramassive star — exploded, giving rise to such a luminous explosion that it might have shone as bright as our entire galaxy. And nobody on Earth saw it. Located in the plane of our Milky Way galaxy, the light was obscured, but thanks to a suite of great, space-based observatories (Hubble, Spitzer, and Chandra), we've been able to piece together exactly what occurred. Not only that, but observations of a light-echo, or reflected light off of the nearby gas, has allowed us to see the light from this explosion centuries later, and learn exactly how it happened.
Shit traveling near the speed of light experiences much less time than shit at non-relativistic speeds.
I don't think relativity enters into this. In space, light travels at the speed of light. And to a photon, time means nothing.
What we have here is a direct path length from the supernova to earth of 11,000 ly. Something went 'bang' 11,300 years ago, so we missed the first signals. But there are gas clouds and other crud floating around which reflect the pulse, making it travel longer paths. We are now seing the reflections with path lengths of 11,300 ly. And as time goes by, we will see reflections with longer and longer path lengths.
This will (in time) be an interesting opportunity to map the structures of the gas clouds surrounding the supernova using successive images (over dozens or hundreds of years) and calculating path differences and the underlying 3D structures causing the reflections.
Have gnu, will travel.
How is this news? The video in TFA is from 2008, check the upload date on Youtube. There must be some weird time dilation effect going on, posting 2008 news is a new low, even for ./ on nowadays.
"Now" spreads at the speed of light so when you see something, it's happening, as far as you are concerned, right now.
I don't think that's how a physicist would define simultaneity. There is a reference frame in which it happened as arbitrarily close to "now" (in that reference frame) as you'd like, but we're not in one of those.
The event which produced the photons happened, as far as I'm concerned, 11,000 years ago.
If you want to say it's happening "now," then any signal we send back in that direction will also get there "now." Except that that "now" will be 22,000 years later then the first "now," which makes no sense.
systemd is Roko's Basilisk.