6 ms·

Hours, and 21 million years, after it happened.

unwantedLetters 15y ago
Thanks for pointing this out. I've obviously not gotten my head around the concept of space-time and the article fails to mention this. Also, http://newscenter.lbl.gov/feature-stories/2011/08/25/supernova/ http://newscenter.lbl.gov/feature-stories/2011/08/25/superno... is perhaps a more official story. They too don't mention that it's discovery was a few hours after it was possible to observe the explosion, not a few hours after the actual explosion.
- VladRussian 15y ago
  "The PTF survey uses a robotic telescope mounted on the 48-inch Samuel Oschin Telescope at Palomar Observatory in Southern California to scan the sky nightly. As soon as the observations are taken, the data travels more than 400 miles to NERSC via the National Science Foundation’s High Performance Wireless Research and Education Network and DOE’s Energy Sciences Network (ESnet). At NERSC, computers running machine learning algorithms in the Real-time Transient Detection Pipeline scan through the data and identify events to follow up on. Within hours of identifying PTF 11kly, this automated system sent the coordinates to telescopes around the world for follow-up observations." can it look like a planet-wide intelligence to an outsider? :) . Interesting to compare to the origins of cybernetics : http://en.wikipedia.org/wiki/Norbert_Wiener#During_and_after_World_War_II http://en.wikipedia.org/wiki/Norbert_Wiener#During_and_after... It seems to me that detect-track-target feedback-looped principle was one of key in the development of intelligence of animals and humans, and it seems to continue its work in developing the intelligence beyond that.
- sophacles 15y ago
  These conversations are useless. Everyone knows that anything we see is strictly in the past and already has happened. Yet for practical purposes, a week ago there was no supernova there. Today a supernova is there. It may help you to look at it like this: a supernova is NOT the star exploding, it is the observation of the star exploding. In one sense, this is wrong, but in another it is really the only freaking thing a supernova can be. Therefore since it wasn't a supernova until humanity saw it being a supernova, it is currently happening. Further, the article only says the supernova is brightening, and that the telescope saw the star early in its explosion a few hours ago. From the reference point of observability, no claim is made that something 21million light years away is being watched now, just the effects of it are being watched right now. Relax and go watch the show.
  - baddox 15y ago
    > Everyone knows that anything we see is strictly in the past and already has happened. Actually, that statement is nonsensical. Choosing the Earth as your point of reference, the supernova is happening exactly when we see it happening.
    - jerf 15y ago
      I don't think it's nonsensical. There is a meaningful way in which it is in the past. Even if you turn yourself into photons, match positions with the supernova remnants, then return to physical form, the supernova is going to evolve though time for quite a ways beyond the current state we observe it in before your physical form has its rendezvous, even if the trip has zero duration for you. Putting a specific time span on how far in the past it is without further specification is dubiously meaningful, saying it is in the past is not nonsensical. Everything we see is always in the past, even if it's just on the other side of the room.
      - baddox 15y ago
        If you set a reference point, then I think it's perfectly sensical to say two events happen simultaneously or "now," but without a set reference point those notions are completely nonsensical. Most educated people understand the principle of relativity (which states that the laws of physics behave consistent in all frames of reference) and the fact that the speed of light is constant regardless of your frame of reference, but we tend to forget the resultant phenomenon called the relativity of simultaneity. Two observers in different frames of reference can't even agree on the order of events, much less the "exact time" they occurred. Now, you can certainly propose the semantic axiom that "everything happened in the past due to the finiteness of the speed of light," but I find that axiom to be pretty useless in scientific discussion. You can suppose that millions of years of stuff has happened to that supernova after "now," but none of those events could have any causal effects on us.
        ars 15y ago
        > Two observers in different frames of reference can't even agree on the order of events Please keep in mind that we and the supernova are more or less in the same frame of reference. So all the ambiguity of simultaneity does not apply here.
mainguy 15y ago
Yeah, I thought that was a little misleading also.
- Natsu 15y ago
  Why would you find it misleading to use our reference frame instead of the star's? There is no absolute "when" but a different time for each observer.
- adobriyan 15y ago
  21 million years is not the point.
- deleted 15y ago
  [deleted]
bfe 15y ago
Not particularly exciting in the sense of being compared with Hollywood special effects. But I'm excited to look at it through my telescope and know that thing I'm looking at is a star exploding in a distant galaxy. And photons from that exploding star that have crossed 21 million light-years of intergalactic void are entering my eyeballs.
- artursapek 15y ago
  I hope you don't take offense to this but I laughed when I saw you're an attorney, because that is so poetic.
  - bfe 15y ago
    I was an astronomer first.
    - deleted 15y ago
      [deleted]
baddox 15y ago
I always have to point this out at the risk of downvotes: it doesn't make sense to say that an event you're currently seeing on Earth "happened 21 million years ago." Both space and time are relative, so if you're choosing Earth as your reference point, the supernova is happening right when you're seeing it.
- ars 15y ago
  No, you are confusing relative time, with transit time (i.e. the time it takes for the information to reach you). Relative time is a real thing, certainly and messes with the idea of simultaneous. But transit time is not that. We and the supernova are more or less in the same frame of reference (we are not accelerating relative to one another, and there isn't much relative velocity difference either). And because of that it is correct to say it happened xxx years ago.
  - baddox 15y ago
    Is that correct? Let's say Bill was born here on Earth on August 26, 2011, "at the same time" astronomers first detected this supernova. On Earth, we observe Bill's birth and the beginning of the supernova to be simultaneous events. However, isn't it true that an observer at the supernova (presuming he could survive) wouldn't agree that Bill's birth and the supernova were simultaneous, would he?
    - mhb 15y ago
      He would because he knows how fast information travels.
    - ars 15y ago
      > On Earth, we observe Bill's birth and the beginning of the supernova to be simultaneous events. No, that is incorrect. We observe that the light from the supernova reached us now, yes. But we are well aware that it actually happened long ago. Both us and the distant observer agree about the order and relative timing of the events. It's only when we are not in the same frame of reference that we would disagree, and that is not the case here.
Mz 15y ago
I don't know exactly where it belongs/fits in this discussion, but some of the remarks here remind me of the example I have used on occasion that you see lightening before you hear thunder because light and sound travel at different speeds even though they both originate with the same event.

Thanks for pointing this out. I've obviously not gotten my head around the concept of space-time and the article fails to mention this. Also, http://newscenter.lbl.gov/feature-stories/2011/08/25/supernova/ http://newscenter.lbl.gov/feature-stories/2011/08/25/superno... is perhaps a more official story. They too don't mention that it's discovery was a few hours after it was possible to observe the explosion, not a few hours after the actual explosion.

VladRussian 15y ago
"The PTF survey uses a robotic telescope mounted on the 48-inch Samuel Oschin Telescope at Palomar Observatory in Southern California to scan the sky nightly. As soon as the observations are taken, the data travels more than 400 miles to NERSC via the National Science Foundation’s High Performance Wireless Research and Education Network and DOE’s Energy Sciences Network (ESnet). At NERSC, computers running machine learning algorithms in the Real-time Transient Detection Pipeline scan through the data and identify events to follow up on. Within hours of identifying PTF 11kly, this automated system sent the coordinates to telescopes around the world for follow-up observations." can it look like a planet-wide intelligence to an outsider? :) . Interesting to compare to the origins of cybernetics : http://en.wikipedia.org/wiki/Norbert_Wiener#During_and_after_World_War_II http://en.wikipedia.org/wiki/Norbert_Wiener#During_and_after... It seems to me that detect-track-target feedback-looped principle was one of key in the development of intelligence of animals and humans, and it seems to continue its work in developing the intelligence beyond that.
sophacles 15y ago
These conversations are useless. Everyone knows that anything we see is strictly in the past and already has happened. Yet for practical purposes, a week ago there was no supernova there. Today a supernova is there. It may help you to look at it like this: a supernova is NOT the star exploding, it is the observation of the star exploding. In one sense, this is wrong, but in another it is really the only freaking thing a supernova can be. Therefore since it wasn't a supernova until humanity saw it being a supernova, it is currently happening. Further, the article only says the supernova is brightening, and that the telescope saw the star early in its explosion a few hours ago. From the reference point of observability, no claim is made that something 21million light years away is being watched now, just the effects of it are being watched right now. Relax and go watch the show.
- baddox 15y ago
  > Everyone knows that anything we see is strictly in the past and already has happened. Actually, that statement is nonsensical. Choosing the Earth as your point of reference, the supernova is happening exactly when we see it happening.
  - jerf 15y ago
    I don't think it's nonsensical. There is a meaningful way in which it is in the past. Even if you turn yourself into photons, match positions with the supernova remnants, then return to physical form, the supernova is going to evolve though time for quite a ways beyond the current state we observe it in before your physical form has its rendezvous, even if the trip has zero duration for you. Putting a specific time span on how far in the past it is without further specification is dubiously meaningful, saying it is in the past is not nonsensical. Everything we see is always in the past, even if it's just on the other side of the room.
    - baddox 15y ago
      If you set a reference point, then I think it's perfectly sensical to say two events happen simultaneously or "now," but without a set reference point those notions are completely nonsensical. Most educated people understand the principle of relativity (which states that the laws of physics behave consistent in all frames of reference) and the fact that the speed of light is constant regardless of your frame of reference, but we tend to forget the resultant phenomenon called the relativity of simultaneity. Two observers in different frames of reference can't even agree on the order of events, much less the "exact time" they occurred. Now, you can certainly propose the semantic axiom that "everything happened in the past due to the finiteness of the speed of light," but I find that axiom to be pretty useless in scientific discussion. You can suppose that millions of years of stuff has happened to that supernova after "now," but none of those events could have any causal effects on us.
      - ars 15y ago
        > Two observers in different frames of reference can't even agree on the order of events Please keep in mind that we and the supernova are more or less in the same frame of reference. So all the ambiguity of simultaneity does not apply here.

mainguy 15y ago

Yeah, I thought that was a little misleading also.

Natsu 15y ago
Why would you find it misleading to use our reference frame instead of the star's? There is no absolute "when" but a different time for each observer.
adobriyan 15y ago
21 million years is not the point.
deleted 15y ago
[deleted]

bfe 15y ago

Not particularly exciting in the sense of being compared with Hollywood special effects. But I'm excited to look at it through my telescope and know that thing I'm looking at is a star exploding in a distant galaxy. And photons from that exploding star that have crossed 21 million light-years of intergalactic void are entering my eyeballs.

artursapek 15y ago
I hope you don't take offense to this but I laughed when I saw you're an attorney, because that is so poetic.
- bfe 15y ago
  I was an astronomer first.
  - deleted 15y ago
    [deleted]

baddox 15y ago

I always have to point this out at the risk of downvotes: it doesn't make sense to say that an event you're currently seeing on Earth "happened 21 million years ago." Both space and time are relative, so if you're choosing Earth as your reference point, the supernova is happening right when you're seeing it.

ars 15y ago
No, you are confusing relative time, with transit time (i.e. the time it takes for the information to reach you). Relative time is a real thing, certainly and messes with the idea of simultaneous. But transit time is not that. We and the supernova are more or less in the same frame of reference (we are not accelerating relative to one another, and there isn't much relative velocity difference either). And because of that it is correct to say it happened xxx years ago.
- baddox 15y ago
  Is that correct? Let's say Bill was born here on Earth on August 26, 2011, "at the same time" astronomers first detected this supernova. On Earth, we observe Bill's birth and the beginning of the supernova to be simultaneous events. However, isn't it true that an observer at the supernova (presuming he could survive) wouldn't agree that Bill's birth and the supernova were simultaneous, would he?
  - mhb 15y ago
    He would because he knows how fast information travels.
  - ars 15y ago
    > On Earth, we observe Bill's birth and the beginning of the supernova to be simultaneous events. No, that is incorrect. We observe that the light from the supernova reached us now, yes. But we are well aware that it actually happened long ago. Both us and the distant observer agree about the order and relative timing of the events. It's only when we are not in the same frame of reference that we would disagree, and that is not the case here.

Mz 15y ago

I don't know exactly where it belongs/fits in this discussion, but some of the remarks here remind me of the example I have used on occasion that you see lightening before you hear thunder because light and sound travel at different speeds even though they both originate with the same event.