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Author | Topic: How is the Universe here? | ||||||||||||||||||||||||||||||||||||||||||
cavediver Member (Idle past 2957 days) Posts: 4129 From: UK Joined: |
No, *I* don't say that :) It may be true in Special Relativity, but not always in General Relativity. The standard cosmological solutions admit a preferred rest-frame: the "comoving" rest-frame. You can say that it is the expansion of the Universe that provides the basis for this rest-frame. We clearly see it in the CMBR, and we have to subtract a doppler component from our observations of the CMBR based on our own peculiar motion wrt this rest-frame. Essentially, the 13.7 Ga age of the Universe is the *maximum* possible age of a test particle emitted at the Big Bang.
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Dr Jack Member (Idle past 1418 days) Posts: 3507 From: Leicester, England Joined: |
Ah, that makes sense. Ta.
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AustinG Member (Idle past 4482 days) Posts: 36 Joined: |
I read over the posts that described how time is different for each oberserver; how a man on mercury would see a solar flare before we do on earth. I get that. What I don't get is how it relates to time. If the solar flare happend at 4:00 p.m. on the sun than it still happend a 4:00 p.m. for observers on earth, they just havn't observed it yet.
If my friend, who livers 30 minutes away, leaves his house at 4:00 and arrives ay my place at 4:30, I wouldn't say he left his house at 4:30 and also arived at 4:30. I would know he left at 4:00 and it took him 30 minutes to get here. Isn't this the same thing as the sun example? Or am I being totally close minded? Can anyone elaborate more for me?
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lyx2no Member (Idle past 4029 days) Posts: 1277 From: A vast, undifferentiated plane. Joined:
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Welcome AustinG
You're correct in your example. If observers on the Sun, Mercury and Earth each had a synchronized Timex then a solar flare happening at four o'clock on the Sun observers watch would be seen to happen at 4:03 on the Mercury observers watch and at 4:08 on the Earth observers watch. And each would know at what time it happened on the other observers watches. No big deal. But now lets give them all super accurate atomic clocks synchronized At Venus' north pole. The Sun observer would have to include a correction for his clock being slow due to the Sun's enormous gravitational field. The Mercury observer would have to include a correction for his clock being fast due to Mercury's rapid orbit. The Earth observer has to account for his gravity changing over the course of the day as the Moon changes position in the sky. More to the point, they each have to take into account on their very accurate clocks every acceleration they don't share in common. Accelerations warp space-time. Genesis 2 17 But of the ponderosa pine, thou shalt not eat of it; for in the day that thou shinniest thereof thou shalt sorely learn of thy nakedness. 18 And we all live happily ever after.
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AustinG Member (Idle past 4482 days) Posts: 36 Joined: |
Yes, but how does one know if time actually slows down because of velocity/gravitational fields? What if only the clock is slowed down?
How would you know either way?
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lyx2no Member (Idle past 4029 days) Posts: 1277 From: A vast, undifferentiated plane. Joined: |
Because there is nothing particularly special about a clock. A clock is merely a device for accounting a sequence of events in time. As a person of habit can be used to set ones watch by, cesium atoms are only of a more stringent habit.
Cosmic ray particles slamming into our upper atmosphere produce daughter particles that should decay before making it to the surface of the Earth. So how is it that they make it down here where we can measure them. By theory, if a daughter particle were moving at 87% of the speed of light — a real slow poke — it should "live" twice as long as we would expect if its time were the same as our own. And this is what is seen. Are we measuring a changing habit of a particle or a habit of space-time? Take your pick. Either all particles and events without exception behave exactly as if time has changed for reasons only beknowst to themselves or time is not the same to all observers. AbE: cavediver, I'm not really sure this is on topic or not because I'm not really sure I (come anywhere close?) understand what the topic is. There is something I vaguely recall about "Why is there something instead of nothing?" I don't know where that comes from… so why haven't I Googled it already? Let me Google it and get back to you with something worth the time (no pun intended). Thanks, I always like reading your stuff. Edited by lyx2no, : Hit the topic somewhere. Edited by lyx2no, : No reason given. Genesis 2 17 But of the ponderosa pine, thou shalt not eat of it; for in the day that thou shinniest thereof thou shalt sorely learn of thy nakedness. 18 And we all live happily ever after.
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Lurkey Junior Member (Idle past 3401 days) Posts: 11 Joined:
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There sure is. If you ever read this - thanks for everything you’ve done on this site cavediver. You're some teacher.
Purely personal, but i have to disagree. There is something about this site that works and I reckon the passing on has a lot to do with it. Like the idea gets marched all the way down the line to a point where I can understand. Then when I finally do get it, the path back up is right there for me to follow. And if one person makes a mistake, others point it out. Tbh, i didn't understand most of the physics here, but still i'm spewing it got jacked. A golden resource lost. Not into bashing, but what the jackers did here was immoral....evil...criminal...like defacing an antiquity.
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cavediver Member (Idle past 2957 days) Posts: 4129 From: UK Joined:
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Oh, I'm here
![]() I'm always lurking but I have so little time these days to contribute much. When I joined EvC in 2005, I was working for myself, and a master of my own time. Now I'm a slave to running my company
Yep, you're right. EvC is rather special, and some of the folks here have more than excelled themselves. That's one reason why I don't feel I'm letting the side down too much - for example, Catholic Scientist's cosmology explanations have become first rate.
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Stile Member Posts: 4077 From: Ontario, Canada Joined: Member Rating: 3.9 |
"Oooooooooohhhhh.... for he's a jolly good fell..." ...no? Anybody? Just me, then? And maybe one day, sometime, you'll be able to continue this thread.
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kofh2u Member (Idle past 3133 days) Posts: 1162 From: phila., PA Joined: |
Kofh2u: Interesting confirmation of the Copenhagen Interpretation which infers the virtual reality become concrete for us when we observe it??? Truth is also virtual, in that it is an ideal that corresponds to a Reality tp which it is congruent. . "God" apparently is the ever unfolding reality which sane people conceive mentally and chosse to accept for their own salvation, isn't it?
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Eli Member (Idle past 2805 days) Posts: 274 Joined:
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That's not the Copenhagen Interpretation.
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