However, it might go supernova in the near future, if it hasn't already
It hasn't already, because we haven't seen it go boom yet. Even if it is half a millennium away in terms of light travel time, from our frame of reference it will only go boom when we observe it to.
What you're saying today is: "It definitely hasn't happened yet." And tomorrow: "It definitely hasn't happened yet." And the day after, if we just happen to see it: "It definitely happened 600 years ago."
It doesn't matter whether we have observed it or not, it might have happened already.
No, he would never say the last line. Time travels at the speed of light. When we see it, it is the same instant of time when it exploded. Or more formally, the two events become causally connected the instant we see the light.
What you're saying today is: "It definitely hasn't happened yet." And tomorrow: "It definitely hasn't happened yet." And the day after, if we just happen to see it: "It definitely happened 600 years ago."
It doesn't matter whether we have observed it or not, it might have happened already.
You might want to read a bit about light cones. An event is considered to have happened in a frame of reference when information regarding the event can reach that frame of reference. So if we see it go boom at 12:00 tomorrow, then in our frame of reference it went boom at 12:00 2009-06-13. Not 640 years ago, even though it took the information regarding the event that long to reach us.
Relativity is cool like that. It is _not_ intuitive!
Really? I have no idea how many times I've heard scientists say that if everything suddenly is dark, it's because the sun burned out 8 minutes earlier, yet what I'm hearing you say is that if the sun burns out at 12:00 my time, I'd see it at 12:00 my time as well.
It's definitely not intuitive then, because the first thing makes a lot more sense to me. Oh, and is this only true for light or for sound as well? If I hear a gun shot from far away, is it then also true that gun wasn't fired until I heard the ban
Assuming you weren't being snarky, he's just speaking in the language of physics. Don't take "observe" literally-- he just meant when the light reaches us. If you were being snarky, then when you close your eyes, you'd be likely to be eaten by a grue.
You may want to cover your eyes and ears. Some of us are going to leave your frame of reference for a moment, and do not wish accidentally reveal any spoilers...
Put differently, Dick Clark's New Year's Rockin' Eve is broadcast in Seattle three hours after it is recorded in New York. You can deny that Dick Clark has yelled Happy New Year because, in your frame of reference, you have yet to observe this. However, you would be wrong. You are free to only acknowledge events that are observed from your fr
Yes, but that's meaningless, and moreover you don't have to speculate. If the light has not reached us yet, then the two events (here&now and the ka-boom) are not causally connected. That is, they are "space-like" separated. You can show that there exists a reference frame with any time duration between two space-like separated events. So, in some reference frame, I'm typing this post *after* the light from the supernova has occurred. In another frame, I'd have to wait a billion years for it to happen.
Relitivity (Score:4, Insightful)
However, it might go supernova in the near future, if it hasn't already
It hasn't already, because we haven't seen it go boom yet. Even if it is half a millennium away in terms of light travel time, from our frame of reference it will only go boom when we observe it to.
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How is this insightful?
What you're saying today is:
"It definitely hasn't happened yet."
And tomorrow:
"It definitely hasn't happened yet."
And the day after, if we just happen to see it:
"It definitely happened 600 years ago."
It doesn't matter whether we have observed it or not, it might have happened already.
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How is this insightful?
What you're saying today is:
"It definitely hasn't happened yet."
And tomorrow:
"It definitely hasn't happened yet."
And the day after, if we just happen to see it:
"It definitely happened 600 years ago."
It doesn't matter whether we have observed it or not, it might have happened already.
You might want to read a bit about light cones. An event is considered to have happened in a frame of reference when information regarding the event can reach that frame of reference. So if we see it go boom at 12:00 tomorrow, then in our frame of reference it went boom at 12:00 2009-06-13. Not 640 years ago, even though it took the information regarding the event that long to reach us.
Relativity is cool like that. It is _not_ intuitive!
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Really? I have no idea how many times I've heard scientists say that if everything suddenly is dark, it's because the sun burned out 8 minutes earlier, yet what I'm hearing you say is that if the sun burns out at 12:00 my time, I'd see it at 12:00 my time as well.
It's definitely not intuitive then, because the first thing makes a lot more sense to me. Oh, and is this only true for light or for sound as well? If I hear a gun shot from far away, is it then also true that gun wasn't fired until I heard the ban
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Yes. In Relativity, there is only one time, and it is always Too Late.
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What happens when we close our eyes?
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Actually, I was just trying to be funny. But I assume you have confused Comic Book Guy with me.</snarky>
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Put differently, Dick Clark's New Year's Rockin' Eve is broadcast in Seattle three hours after it is recorded in New York. You can deny that Dick Clark has yelled Happy New Year because, in your frame of reference, you have yet to observe this. However, you would be wrong. You are free to only acknowledge events that are observed from your fr
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So, if nobody looks it will never go nova? Hmm ... now we just need to find a way to make sure nobody ever observes it so we can "save the earth" ... ;)
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Wrong mod: This is FUNNY.