While I understand what they mean...
-
Marc Clifton wrote:
it actually happened several tens of thousands of years ago
That's not correct. Your statement sounds like there's something like absolute time. When saying "it happened 28000 years ago"; that implies that it happened at the same time as events on earth that were 28000 years ago. But the only places where that's true are points with equal distance from earth and the supernova; and I don't think those points (probably in the middle of empty space) are particularly interesting... so why use them as reference for your time scale? It makes more sense to use the time on earth, and there "The supernova explosion occurred about 140 years ago" is correct.
Daniel Grunwald wrote:
that implies that it happened at the same time as events on earth that were 28000 years ago
And it did, it just took 28000 years for the light to get here!
xacc.ide - now with TabsToSpaces support
IronScheme - 1.0 alpha 3 out now -
No, no, no. > A planet 141 lightyears further away would observe it next year. "would observe it next year" does not make any sense. You're jumping with your reference frame from earth to that planet. That's not allowed. You're thinking in absolute time. But there's no such thing as absolute time.
Daniel Grunwald wrote:
That's not allowed. You're thinking in absolute time. But there's no such thing as absolute time.
Which is precisely the point where physicists cross over from being scientists to being thought police. What if someone had told Einstien, that's not allowed, you're thinking in relative time. But there's no such ting as relative time?
"The secret of happiness is freedom, and the secret of freedom, courage." Thucydides (B.C. 460-400)
-
Daniel Grunwald wrote:
That's not allowed. You're thinking in absolute time. But there's no such thing as absolute time.
Which is precisely the point where physicists cross over from being scientists to being thought police. What if someone had told Einstien, that's not allowed, you're thinking in relative time. But there's no such ting as relative time?
"The secret of happiness is freedom, and the secret of freedom, courage." Thucydides (B.C. 460-400)
When writing "That's not allowed", I meant "That's not allowed in the relativity theory, as otherwise you would end up with contradictions". You're free to use another theory.
-
All time is absolute. If a man sends a signal from the surface of the moon, it take 2.5 seconds to reach earth. That signal is not happening "NOW" it Happened 2.5sec AGO. Unless you have some kind of Alcubierre Drive that we don't know about, I feel you need to think about this. FTL is possible, and indeed a FTL machine has been patented. It really is a simple device. However, back to the point. You are stating that you wish to be living in a Geotemporal Universe, and that would be a REALLY bad idea. For a start, none of the GPS systems would work, as time travels more slowly in orbit than it does on earth, easy to see, there are thousands of corrections to the GPS on board clocks every day. This is substantiated by Relativity, that the Time element of Space/Time is inherant to the localised Gravity Field, and therefore as earth's gravity is not ubiquitous throughout the universe, time cannot be geotemporal. Also if things happened only when we observe them rather than long ago, it means that EVERYTHING we observe in the universe is happening concurrently, and if this were the case, the most distant galaxies would only now be forming! I suggest that if you really think it true then you spend the next 100 years totally rewriting the science of Physics that greater minds than ours have worked on! :)
------------------------------------ "I want you to imagine I have a blaster in my hand" - Zaphod Beeblebrox. "You DO have a blaster in your hand" - Freighter Pilot "Yeah, so you don't have to tax your imagination too hard" - Zaphod Beeblebrox
I know I argumented with special relativity (because I don't know general relativity well), and I realize GPS wouldn't work if not corrected for the effects of general relativity. However, I don't see where general relativity proposes absolute time???
-
This: The supernova explosion occurred about 140 years ago, can be rather confusing to people who don't get that what they really mean is that the light from the explosion would have reached us 140 years ago, but (as the star is near the center of the galaxy) it actually happened several tens of thousands of years ago (I don't recall how many light years it is to the center of our galaxy off the top of my head.) Is anyone else bothered by this loosey-goosey journalism, which appears to be occurring more frequently even within the scientific community? Link[^] Marc
It happens all the time. My particular bugbear is the use of lightyear as a measure of time or maybe the words Wattage and Ampage, it's a close call.
-
All time is absolute. If a man sends a signal from the surface of the moon, it take 2.5 seconds to reach earth. That signal is not happening "NOW" it Happened 2.5sec AGO. Unless you have some kind of Alcubierre Drive that we don't know about, I feel you need to think about this. FTL is possible, and indeed a FTL machine has been patented. It really is a simple device. However, back to the point. You are stating that you wish to be living in a Geotemporal Universe, and that would be a REALLY bad idea. For a start, none of the GPS systems would work, as time travels more slowly in orbit than it does on earth, easy to see, there are thousands of corrections to the GPS on board clocks every day. This is substantiated by Relativity, that the Time element of Space/Time is inherant to the localised Gravity Field, and therefore as earth's gravity is not ubiquitous throughout the universe, time cannot be geotemporal. Also if things happened only when we observe them rather than long ago, it means that EVERYTHING we observe in the universe is happening concurrently, and if this were the case, the most distant galaxies would only now be forming! I suggest that if you really think it true then you spend the next 100 years totally rewriting the science of Physics that greater minds than ours have worked on! :)
------------------------------------ "I want you to imagine I have a blaster in my hand" - Zaphod Beeblebrox. "You DO have a blaster in your hand" - Freighter Pilot "Yeah, so you don't have to tax your imagination too hard" - Zaphod Beeblebrox
In the end, it all boils down to your definition of "NOW". How do you define a NOW that's valid regarding to relativity and isn't restricted to a specific reference frame?
-
When writing "That's not allowed", I meant "That's not allowed in the relativity theory, as otherwise you would end up with contradictions". You're free to use another theory.
It is ENTIRELY allowed in both Special and General relativity. Relativity only applies to OBSERVATION. Gravitational Lensing for example can distort the appearance of the passage of time, but only to the observer, anyone travelling on a light beam would not notice it and would still be under the rules of ABSOLUTE time. Ye Gods, Relativity even explains how freezers work, it is a simple equation. c, the speed of light can be anything from 13mph to 300c, c is only a constant when you don't go mucking about with it. Since c can be changed, the time on which c events occur are relative to the c event, not relative to the rest of the universe, that is why time dilates, it has to fill the void left by delta c, which cannot be a void therefore c +/- delta c equals delta Kt! Physics is fun! :)
------------------------------------ "I want you to imagine I have a blaster in my hand" - Zaphod Beeblebrox. "You DO have a blaster in your hand" - Freighter Pilot "Yeah, so you don't have to tax your imagination too hard" - Zaphod Beeblebrox
-
I know I argumented with special relativity (because I don't know general relativity well), and I realize GPS wouldn't work if not corrected for the effects of general relativity. However, I don't see where general relativity proposes absolute time???
Causal nexus. Once an avent happens, it is set, it cannot be undone. Therefore (and Heisenburg proved this) events must happen and must continue to happen. They cannot happen in one place and not in another. My good friend Frank Close also argued with me years ago about the speed of gravity. I argued it had to be c, he argued it didn't. He was basing it on available knowledge, I argued from the gut. Recently proven, I was right. (I don't take credit, it wasn't my work, but I did email him and blow a raspberry!) So if the event takes place and can be observed in one place before another then by definition there is a vector and a time involved. Therefore, IT DIDN'T HAPPEN 140 YEARS AGO!
------------------------------------ "I want you to imagine I have a blaster in my hand" - Zaphod Beeblebrox. "You DO have a blaster in your hand" - Freighter Pilot "Yeah, so you don't have to tax your imagination too hard" - Zaphod Beeblebrox
-
In the end, it all boils down to your definition of "NOW". How do you define a NOW that's valid regarding to relativity and isn't restricted to a specific reference frame?
Now is Now. The Event was 28140 years ago, but the observation of the event was NOW. It is like watching a recording of a horse race. The race may have occured yesterday, but because you were observing it today, it is happening NOW to you, but in reality it is 24 hours old!
------------------------------------ "I want you to imagine I have a blaster in my hand" - Zaphod Beeblebrox. "You DO have a blaster in your hand" - Freighter Pilot "Yeah, so you don't have to tax your imagination too hard" - Zaphod Beeblebrox
-
Isn't it that the object is 28000 light years distant from our current position? From our perspective/frame of reference the light from the explosion first reached here about 140 years ago. What we see now is the object as it appears now from our reference point. I think the media try to put it as simplistically as possible for headline, audience numbers and sales purposes.
Ah you mean 'Physics for the Hard of Understanding'! :)
------------------------------------ "I want you to imagine I have a blaster in my hand" - Zaphod Beeblebrox. "You DO have a blaster in your hand" - Freighter Pilot "Yeah, so you don't have to tax your imagination too hard" - Zaphod Beeblebrox
-
It happens all the time. My particular bugbear is the use of lightyear as a measure of time or maybe the words Wattage and Ampage, it's a close call.
Parsecs and the Kessel Run! :)
------------------------------------ "I want you to imagine I have a blaster in my hand" - Zaphod Beeblebrox. "You DO have a blaster in your hand" - Freighter Pilot "Yeah, so you don't have to tax your imagination too hard" - Zaphod Beeblebrox
-
When writing "That's not allowed", I meant "That's not allowed in the relativity theory, as otherwise you would end up with contradictions". You're free to use another theory.
Thanks, I'll stick with CQM. :)
"The secret of happiness is freedom, and the secret of freedom, courage." Thucydides (B.C. 460-400)
-
Now is Now. The Event was 28140 years ago, but the observation of the event was NOW. It is like watching a recording of a horse race. The race may have occured yesterday, but because you were observing it today, it is happening NOW to you, but in reality it is 24 hours old!
------------------------------------ "I want you to imagine I have a blaster in my hand" - Zaphod Beeblebrox. "You DO have a blaster in your hand" - Freighter Pilot "Yeah, so you don't have to tax your imagination too hard" - Zaphod Beeblebrox
Dalek Dave wrote:
Now is Now.
Well, you are right with your idea of now; but I have a different idea of now, and I think it's also valid - it depends on how you think of the universe; for me, observation=event; I can live without absolute time. From http://www.badastronomy.com/bablog/2008/05/14/youngest-galactic-supernova-not-aliens-found/#comment-175177[^]:
Think of it this way: we literally cannot know what’s happening “now” at that distance; we have to wait 28,000 years to find out. In point of fact, there is no “now” at that distance, according to the equations of relativity. Now is simply now, and that means that what we see happening through our telescopes is happening now.
And another comment there:
1. Phil is correct about the “time” of the explosion. It seems odd, but it doesn’t make physical sense to talk about when something “actually” happened. This is why astronomers always talk about things in “Earth time,” this is, when we actually observed it.
So you're free to invent an absolute time as you did, but when dealing with observations, absolute time cannot exist[^]. But please enlighten me if something in general relativity/more recent theories renders my idea of the universe invalid.
-
Dalek Dave wrote:
Now is Now.
Well, you are right with your idea of now; but I have a different idea of now, and I think it's also valid - it depends on how you think of the universe; for me, observation=event; I can live without absolute time. From http://www.badastronomy.com/bablog/2008/05/14/youngest-galactic-supernova-not-aliens-found/#comment-175177[^]:
Think of it this way: we literally cannot know what’s happening “now” at that distance; we have to wait 28,000 years to find out. In point of fact, there is no “now” at that distance, according to the equations of relativity. Now is simply now, and that means that what we see happening through our telescopes is happening now.
And another comment there:
1. Phil is correct about the “time” of the explosion. It seems odd, but it doesn’t make physical sense to talk about when something “actually” happened. This is why astronomers always talk about things in “Earth time,” this is, when we actually observed it.
So you're free to invent an absolute time as you did, but when dealing with observations, absolute time cannot exist[^]. But please enlighten me if something in general relativity/more recent theories renders my idea of the universe invalid.
Daniel Grunwald wrote:
So you're free to invent an absolute time as you did, but when dealing with observations, absolute time cannot exist[^].
Correct, when dealing with OBSERVATIONS you deal with the time as you see it. But we are not talking about observations, we are talking about the event itself. I grant you that from our perspective it was OBSERVED to have happened 140 years ago, but that has NOTHING to do with when it ACTUALLY happened. These things are important. Quantum Physicists are often trying to recreate things that happened in the first few seconds of the universe, not things that happened last Monday. So when the telescopes are turned to the dark ages of the universe, ie after the backglow of Big Bang went away, but before the first stars shone, they are not talking of things happening now, and their language is not of a present day occurance, but of 13.5 billion years ago.
------------------------------------ "I want you to imagine I have a blaster in my hand" - Zaphod Beeblebrox. "You DO have a blaster in your hand" - Freighter Pilot "Yeah, so you don't have to tax your imagination too hard" - Zaphod Beeblebrox
-
Daniel Grunwald wrote:
So you're free to invent an absolute time as you did, but when dealing with observations, absolute time cannot exist[^].
Correct, when dealing with OBSERVATIONS you deal with the time as you see it. But we are not talking about observations, we are talking about the event itself. I grant you that from our perspective it was OBSERVED to have happened 140 years ago, but that has NOTHING to do with when it ACTUALLY happened. These things are important. Quantum Physicists are often trying to recreate things that happened in the first few seconds of the universe, not things that happened last Monday. So when the telescopes are turned to the dark ages of the universe, ie after the backglow of Big Bang went away, but before the first stars shone, they are not talking of things happening now, and their language is not of a present day occurance, but of 13.5 billion years ago.
------------------------------------ "I want you to imagine I have a blaster in my hand" - Zaphod Beeblebrox. "You DO have a blaster in your hand" - Freighter Pilot "Yeah, so you don't have to tax your imagination too hard" - Zaphod Beeblebrox
OK. But back to the actual topic: From what I've read, the convention for astronomers is to date events by the observation time on earth. This has the huge advantage that they don't need to adjust all their times whenever the distance measurement is improved.
-
Marc Clifton wrote:
I don't recall how many light years it is to the center of our galaxy off the top of my head.
We could ask Chuck Norris. He's driven there and back twice - in a Yugo.
"Why don't you tie a kerosene-soaked rag around your ankles so the ants won't climb up and eat your candy ass..." - Dale Earnhardt, 1997
-----
"...the staggering layers of obscenity in your statement make it a work of art on so many levels." - Jason Jystad, 10/26/2001 -
OK. But back to the actual topic: From what I've read, the convention for astronomers is to date events by the observation time on earth. This has the huge advantage that they don't need to adjust all their times whenever the distance measurement is improved.
As I said in my previous answer... That is for Observations, and I agree with you on this.
------------------------------------ "I want you to imagine I have a blaster in my hand" - Zaphod Beeblebrox. "You DO have a blaster in your hand" - Freighter Pilot "Yeah, so you don't have to tax your imagination too hard" - Zaphod Beeblebrox
-
As I said in my previous answer... That is for Observations, and I agree with you on this.
------------------------------------ "I want you to imagine I have a blaster in my hand" - Zaphod Beeblebrox. "You DO have a blaster in your hand" - Freighter Pilot "Yeah, so you don't have to tax your imagination too hard" - Zaphod Beeblebrox
Another interesting point of view: http://www.badastronomy.com/bablog/2008/05/14/youngest-galactic-supernova-not-aliens-found/#comment-175593[^]
# In our reference frame (and approximately that of the supernova) it is perfectly fine to say that the SN happened 28,140 years ago, but implicit in that statement is the assumption that the one-way speed of light is c. Reasonable though as it is, this is not an observable fact. The observable fact is that the two-way speed of light is c on average. To find the one-way speed of light, you need synchronized clocks at a distance. However, to synchronize clocks at a distance you need to know the one-way speed of light. You can never get around this, not even with slow clock transport (a la Eddington). The Google search term is “conventionality of simultaneity”. [..] Sorry, I forgot to make my point: The point is that you can choose anything for the one-way speed of light, as long as the round-trip time is 2d/c with d the distance. In particular, you can argue that it did not take the light any time at all to span the 28,000 LY (sic!).
It appears that there are infinite valid possibilities for the actual event date, so I'm going to stick with the observations. EDIT: the point of physics is to have a model to predict observations, isn't it? Any talk about non-observable realities sounds like religion to me...
modified on Thursday, May 15, 2008 10:57 AM
-
All time is absolute. If a man sends a signal from the surface of the moon, it take 2.5 seconds to reach earth. That signal is not happening "NOW" it Happened 2.5sec AGO. Unless you have some kind of Alcubierre Drive that we don't know about, I feel you need to think about this. FTL is possible, and indeed a FTL machine has been patented. It really is a simple device. However, back to the point. You are stating that you wish to be living in a Geotemporal Universe, and that would be a REALLY bad idea. For a start, none of the GPS systems would work, as time travels more slowly in orbit than it does on earth, easy to see, there are thousands of corrections to the GPS on board clocks every day. This is substantiated by Relativity, that the Time element of Space/Time is inherant to the localised Gravity Field, and therefore as earth's gravity is not ubiquitous throughout the universe, time cannot be geotemporal. Also if things happened only when we observe them rather than long ago, it means that EVERYTHING we observe in the universe is happening concurrently, and if this were the case, the most distant galaxies would only now be forming! I suggest that if you really think it true then you spend the next 100 years totally rewriting the science of Physics that greater minds than ours have worked on! :)
------------------------------------ "I want you to imagine I have a blaster in my hand" - Zaphod Beeblebrox. "You DO have a blaster in your hand" - Freighter Pilot "Yeah, so you don't have to tax your imagination too hard" - Zaphod Beeblebrox
Dalek Dave wrote:
FTL is possible, and indeed a FTL machine has been patented. It really is a simple device.
Citation please? I'd love to read on this
"Every time Lotus Notes starts up, somewhere a puppy, a kitten, a lamb, and a baby seal are killed. Lotus Notes is a conspiracy by the forces of Satan to drive us over the brink into madness. The CRC-32 for each file in the installation includes the numbers 666." Gary Wheeler "You're an idiot." John Simmons, THE Outlaw programmer "I realised that all of my best anecdotes started with "So there we were, pissed". Pete O'Hanlon
-
Isn't it that the object is 28000 light years distant from our current position? From our perspective/frame of reference the light from the explosion first reached here about 140 years ago. What we see now is the object as it appears now from our reference point. I think the media try to put it as simplistically as possible for headline, audience numbers and sales purposes.
