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Possible Supernova In Nearby Spiral Galaxy
New submitter Zburatorul writes "In an electronic telegram to the IAU, an Italian astronomer reports his discovery of a possible supernova (magnitude R = 15) near spiral galaxy M95 on images taken March 16th. Many more independent and confirming observations are trickling in. The Bad Astronomer, Phil Plait, has a more layman-friendly article about it. The bad news: it won't be visible with the naked eye. The good news: it's not going to kill us."
The bad news: It won't be visible to the naked eye.
Bummer man! Bummer!
The good news: It's not going to kill us.
Well THAT sucks!
Wait, what?
More likely cause is that they got their version of the Large Hadron Collider up to full power.
Since it occurred 40 million years ago, it must have killed off the dinosaurs.
I've received some nice pictures of the galaxy+SN which I just posted to the blog as well. Looks like this is a Type II, the explosion of a massive star at the end of its short life.
*** Phil Plait, aka The Bad Astronomer http://www.badastronomy.com
An "electronic telegram?" Great, let's head up to Mauna Kea and confirm their results. I propose we travel by horseless sleigh.
Huh?
It happened ~40 million years ago. We're just now seeing it.
Not a hard concept, not even relativity really. Go outside, see a gunshot from a great distance (or, well, anything else loud). You'll see it before you hear it. At such relatively short distances, light takes very little time to reach your eye, but sound takes much longer. Now increase the distance, and light takes a long time too. Bam.
... still waiting for this free-as-in-beer free beer I keep hearing about.
If Betelgeuse, very much in our galaxy, and quite visible to the naked eye even before it goes supernova, is no threat (and it's not, though it could go supernova any time in the next million years), why on Earth would we be worried about an explosion in another galaxy?
Supernova occur (and are observed) fairly regularly. The estimated rate of supernova production in a galaxy the size of the Milky Way is about one every 50 years. We know of millions of galaxies. It's always nice to catch one as it's occurring, especially one as close as this, but the summary is just ridiculous.
No there really is no absolute present in relativity. We can calculate that this supernova occurred 40 million years ago, simultaneously with some event on Earth, but an alien whose spaceship was flying past Earth 40 million years ago at near light speed and who later sees the light from the supernova would not calculate that those two events were simultaneous. Neither it, nor we, is wrong. Simultaneity depends on how you are moving.
What relativity does, indepdendently of how you are moving, is divide the universe into five parts:
* your past -- events from which you could have received a slower-than-light message by now
* your past light cone -- events from which a light-speed signal is just now arriving
* your future light cone -- events which might receive a light-speed signal if your send it now
* your future -- events which could receive a slower-than-light message from you
* the rest
No observer will disagree (except by mistake) about which of these parts any given event is in with respect to you.
The supernova is on our past light cone. In our stationary reference frame it's about 37 million years away, but again, a moving observer would come up with a different number.
Back of the envolope calculation follows:
Distance to SN1987a = 1.9x10^5 light years
Distance to M95 = 4x10^7 light years
Ratio of neutrino flux SN1987a / M95 = (1.9/400)^2 = 2.2x10^-5
Number of neutrinos detected at Kamiokanda from SN1987a = 10
Sensitivity of Super-Kamiokanda (Super-K) = 20x that of Kamiokanda
Expected number of nu's from M95 at Super-K = 20x10x2.2x10^-5 = 0.004 :-(
Well, according to the most popular view of QM, a wave function doesn't collapse until an observation is made. So unless there are alien species that live closer to it and watch the skies, it has spent the last 40My in a superposition of "went nova" and "didn't go nova". So in some sense it "happened" just now.
No not quite. The word is "measurement" not "observation".
Once the photon gets absorbed by Anything, it has been measured, or as you call it "observed". This can be a spec of dust floating in space, or a bit of rock or gas on a dead world. It could be next to anything that absorbs that photon to collapse its wave, and that something does not need to be alive or conscious or more than just a simple little atom of hydrogen.
Also with relativity you can not use "when something happens" alone as a metric. No such thing exists. The question is "when something happens, from what point of view"
From the stars point of view, yes it happened long ago and our part of the universe is just now being affected by it and seeing it.
From our point of view, the light just made it here, so it just happened.