Time: is it "for realz"? A jolly good discussion lies within.

Ketherial · August 2007

MikeMan wrote: »

Okay, look. By "the future has already happened," I mean that, for relativity to make sense, there needs to be a universe which encompasses all past and future events at once. Otherwise, it would make no sense to allow for these relativistic effects. Since these relativistic effects have been proven to occur, there necessarily must be a "future" out there, at all times, as must there be a past.

what do you mean when you say "make sense"? i simply see relativity as a phenomenon where objects experience "time" differently depending on the speed at which they move. i dont see how this affects the "past" or "future" at all.

Perhaps it would be easier if I quoted something for you. Greene uses the example of Chewbacca, and not Blargle, but the example is the exact same thing (I ripped it off from him):

Greene wrote:

You see, Chewie's conception of reality, his freeze-frame mental image, his conception of what exists now, is every bit as real for him as our conception of reality is for us. So, in assessing what constitutes reality, it would be stunningly narrow-minded if we didn't also include his perspective. For Newton, such an egalitarian approach wouldn't make the slightest difference, because, in a universe with absolute space and absolute time, everyone's now-slice coincides. But in a relativistic universe, our universe, it makes a big difference. Whereas our familiar conception of what exists right now amounts to a single now-slice -- we usually view the past as gone and the future as yet to be -- we must augment this image with Chewie's now-slice, a now-slice that, as the discussion revealed, can differ substantially from our own. Furthermore, since Chewie's initial location and the speed with which he moves are arbitrary, we should include the now-slices associated with all possibilities. These now-slices, as in our discussion above, would be centered on Chewie's -- or some other real or hypothetical observer's -- initial location in space and would be rotated at an angle that depends on the velocity chosen. (The only restriction ceoms from the speed limit set by light.)... The collection of all these now-slices fills out a substantial region of the spacetime loaf. In fact, if space is infinite -- if now-slices extended infinitely far -- then the rotated now-slices can be centered arbitrarily far away, and hence their union sweeps through every point in the spacetime loaf.

So: if you buy the notion that reality consists of the things in your freeze-frame mental image right now, and if you agree that your now is no more valid than the now of someone located far away in space who can move freely, then reality encompasses all of the events in spacetime. The total loaf exists. Just as we envision all of space as really being out there, as really existing, we should also envision all of time as really being out there, as really existing, too. Past, present and future certainly appear to be distinct entities. But, as Einstein once said, "For we convinced physicists, the distinction between past, present, and future is only an illusion, however persistent." The only thing that's real is the whole of space-time.

If a goddamned quote from Einstein himself is not sufficient to show you you do not understand relativity, I give up.

That's from pages 138-139 of The Fabric of the Cosmos by Brian Greene.

no, it doesn't show me that i don't understand relativity. it's a famous quote and i think it's hilarious that that greene took einstein's quote out of context and tried to apply it to his metaphysics.

einstein wrote that in a letter to besso's family after his friend besso died, trying to console them. the whole quote goes something like this:

now he [besso] has departed from this strange little world ahead of me. that means nothing. people like us, who believe in physics, know that the distinction between past, present and future is only a stubbornly persistent illusion."

einstein's quote only shows that he thought absolute time was an illusion (which was the prevailing thought of the time).

but that doesnt mean that events in the past, present and future can be actually "condensed" or "distorted" by an observer. it just means that how we experience time may be different from how others experience time.

personally, i really think you should just admit that you overstated the point in your zeal to write something about relativity.

MikeMan · August 2007

Ketherial wrote: »

MikeMan wrote: »

Okay, look. By "the future has already happened," I mean that, for relativity to make sense, there needs to be a universe which encompasses all past and future events at once. Otherwise, it would make no sense to allow for these relativistic effects. Since these relativistic effects have been proven to occur, there necessarily must be a "future" out there, at all times, as must there be a past.

what do you mean when you say "make sense"? i simply see relativity as a phenomenon where objects experience "time" differently depending on the speed at which they move. i dont see how this affects the "past" or "future" at all.

Perhaps it would be easier if I quoted something for you. Greene uses the example of Chewbacca, and not Blargle, but the example is the exact same thing (I ripped it off from him):

Greene wrote:

You see, Chewie's conception of reality, his freeze-frame mental image, his conception of what exists now, is every bit as real for him as our conception of reality is for us. So, in assessing what constitutes reality, it would be stunningly narrow-minded if we didn't also include his perspective. For Newton, such an egalitarian approach wouldn't make the slightest difference, because, in a universe with absolute space and absolute time, everyone's now-slice coincides. But in a relativistic universe, our universe, it makes a big difference. Whereas our familiar conception of what exists right now amounts to a single now-slice -- we usually view the past as gone and the future as yet to be -- we must augment this image with Chewie's now-slice, a now-slice that, as the discussion revealed, can differ substantially from our own. Furthermore, since Chewie's initial location and the speed with which he moves are arbitrary, we should include the now-slices associated with all possibilities. These now-slices, as in our discussion above, would be centered on Chewie's -- or some other real or hypothetical observer's -- initial location in space and would be rotated at an angle that depends on the velocity chosen. (The only restriction ceoms from the speed limit set by light.)... The collection of all these now-slices fills out a substantial region of the spacetime loaf. In fact, if space is infinite -- if now-slices extended infinitely far -- then the rotated now-slices can be centered arbitrarily far away, and hence their union sweeps through every point in the spacetime loaf.

So: if you buy the notion that reality consists of the things in your freeze-frame mental image right now, and if you agree that your now is no more valid than the now of someone located far away in space who can move freely, then reality encompasses all of the events in spacetime. The total loaf exists. Just as we envision all of space as really being out there, as really existing, we should also envision all of time as really being out there, as really existing, too. Past, present and future certainly appear to be distinct entities. But, as Einstein once said, "For we convinced physicists, the distinction between past, present, and future is only an illusion, however persistent." The only thing that's real is the whole of space-time.

If a goddamned quote from Einstein himself is not sufficient to show you you do not understand relativity, I give up.

That's from pages 138-139 of The Fabric of the Cosmos by Brian Greene.

no, it doesn't show me that i don't understand relativity. it's a famous quote and i think it's hilarious that that greene took einstein's quote out of context and tried to apply it to his metaphysics.

einstein wrote that in a letter to besso's family after his friend besso died, trying to console them. the whole quote goes something like this:

now he [besso] has departed from this strange little world ahead of me. that means nothing. people like us, who believe in physics, know that the distinction between past, present and future is only a stubbornly persistent illusion."

einstein's quote only shows that he thought absolute time was an illusion (which was the prevailing thought of the time).

but that doesnt mean that events in the past, present and future can be actually "condensed" or "distorted" by an observer. it just means that how we experience time may be different from how others experience time.

personally, i really think you should just admit that you overstated the point in your zeal to write something about relativity.

You misunderstand Einstein. "Absolute time is an illusion?" What is that nonsense, and how do you get it from his quote in context? I overstated nothing; this is what relativity says. I'd personally take what a respected physicist has to say about relativity over your poor understanding.

I'm done arguing. But by all means, keep trying to overthrow the establishment.

Ketherial · August 2007

MikeMan wrote: »

You misunderstand Einstein. "Absolute time is an illusion?" What is that nonsense, and how do you get it from his quote in context? I overstated nothing; this is what relativity says. I'd personally take what a respected physicist has to say about relativity over your poor understanding.

I'm done arguing. But by all means, keep trying to overthrow the establishment.

now i really think you need to read up more.

MikeMan · August 2007

Cute. The controversy about absolute time with respect to Newtonian concepts was one against which Einstein and his contemporaries were busy rebelling, but you, for no reason, took that quote and applied it just to absolute time, and not to space-time in general.

Hence, what is that nonsense, and how do you get it from his quote?

Ketherial · August 2007

MikeMan wrote: »

Cute. The controversy about absolute time with respect to Newtonian concepts was one against which Einstein and his contemporaries were busy rebelling, but you, for no reason, took that quote and applied it just to absolute time, and not to space-time in general.

Hence, what is that nonsense, and how do you get it from his quote?

hahahah.

you're the one who quoted greene using einstein's quote way out of context.

i'm just putting it back into the context of the time.

MikeMan · August 2007

Ketherial wrote: »

MikeMan wrote: »

Cute. The controversy about absolute time with respect to Newtonian concepts was one against which Einstein and his contemporaries were busy rebelling, but you, for no reason, took that quote and applied it just to absolute time, and not to space-time in general.

Hence, what is that nonsense, and how do you get it from his quote?

hahahah.

you're the one who quoted greene using einstein's quote way out of context.

i'm just putting it back into the context of the time.

Greene just got done explaining how you're wrong. You have yet to give me a reason to believe you over him.

Ketherial · August 2007

MikeMan wrote: »

Ketherial wrote: »

MikeMan wrote: »

Cute. The controversy about absolute time with respect to Newtonian concepts was one against which Einstein and his contemporaries were busy rebelling, but you, for no reason, took that quote and applied it just to absolute time, and not to space-time in general.

Hence, what is that nonsense, and how do you get it from his quote?

hahahah.

you're the one who quoted greene using einstein's quote way out of context.

i'm just putting it back into the context of the time.

Greene just got done explaining how you're wrong. You have yet to give me a reason to believe you over him.

uh, no he didn't. are you sure you read that passage? it says nothing about condensing time, only about how various time slices exist together.

why don't we email him with this thread and see who he agrees with. hahahaha.

greene(at)phys.columbia.edu

MikeMan · August 2007

Ketherial wrote: »

MikeMan wrote: »

Ketherial wrote: »

MikeMan wrote: »

Cute. The controversy about absolute time with respect to Newtonian concepts was one against which Einstein and his contemporaries were busy rebelling, but you, for no reason, took that quote and applied it just to absolute time, and not to space-time in general.

Hence, what is that nonsense, and how do you get it from his quote?

hahahah.

you're the one who quoted greene using einstein's quote way out of context.

i'm just putting it back into the context of the time.

Greene just got done explaining how you're wrong. You have yet to give me a reason to believe you over him.

uh, no he didn't. are you sure you read that passage? it says nothing about condensing time, only about how various time slices exist together.

why don't we email him with this thread and see who he agrees with. hahahaha.

greene(at)phys.columbia.edu

Feel free. The only part of this thread (I'm re-reading his book because of it) that I am misguided about was that Blargle's condensing would not span the past AND future when he moved away from earth. It would condense the past if he moved away, and the future if he moved towards.

Everything else I believe to be an accurate rendition of his views. I'm curious, though; what part of "the reality encompasses all of the events in space-time" don't you understand?

Perhaps I should continue on in the book for you. I'm not making this stuff up.

Greene wrote:

In this way of thinking, events, regardless of when they happen from any particular perspective, just are. They all exist. They eternally occupy their particular point in spacetime. There is no flow. If you were having a great time at the stroke of midnight on New Year's Eve, 1999, you still are, since that is just one immutable location in spacetime. It is tough to accept this description, since our worldview so forcefully distinguishes between past, present, and future. But if we state intently at this familiar temporal scheme and confront it with the cold hard facts of modern physics, its only place of refuge seems to lie within the human mind.

So you're gonna tell me that you can read that quote, and the one preceding it, and tell me with a straight face you think Brian Greene is not saying time's flow is an illusion according to modern physics.

Gorak · August 2007

Greene's clearly just making a semantic argument.

Ketherial wrote: »

Gorak wrote: »

Ketherial wrote: »

the atomic reality i keep mentioning is how any atom (or more useful to our conversation, any living cell) is affected by the passage of "time" (e.g. left to my own devices my heart stops beating after the passage of approximately 80 years or so).

Time does not "pass".

are you making a semantics argument?

Marty81 · August 2007

MikeMan wrote: »

Marty81 wrote: »

which is just plain fucking wrong.

MikeMan wrote: »

indeed it would be, had I said it.

Except you do say it. The thing is, you're saying a lot of stuff that's correct, and then you go and say absurd things like the things I've bolded below:

MikeMan wrote:

So, yeah, we've experienced the full amount of time. But that time can be tweaked and distorted depending on where you are. It's not just the perception. It's the actual simultaneity and duration of the events themselves. All are affected. So Blargle's perspective is not just some wank-off thought experiment. Blargle's perspective, BECAUSE IT IS EQUALLY TRUE, shows that time is as fluid as space. (that doesn't even mean anything!) It shows that our perception of events and simultaneity is flawed, because we regard them as absolutes. It also shows that events that we would consider in our future, in some sense already occurred, because a simple change of perspective can condense them into the present, in an actual, real sense.

None of those things are absurd. Please read up on things before calling into question actual, demonstrated, principles of relativity. This is getting wearisome.

Er, just to be clear, are you saying that a strategically placed observer can see into my future? Because the last thing I bolded certainly seems to say so. I dunno, maybe you're just wording things really strangely and people are getting frustrated.

Marty81 wrote:

Anyway, I have a quick question unrelated to the current discussion because I forgot: When can two observers A and B agree on the order of two events X and Y?

When they are not moving with respect to one another.

Actually, I think there's more to it than that. I'm not asking about simultaneity, just order. I seem to remember it has something to do with whether certain things are within certain light cones or something.

MikeMan · August 2007

Marty81 wrote: »

MikeMan wrote: »

Marty81 wrote: »

which is just plain fucking wrong.

MikeMan wrote: »

indeed it would be, had I said it.

Except you do say it. The thing is, you're saying a lot of stuff that's correct, and then you go and say absurd things like the things I've bolded below:

MikeMan wrote:

So, yeah, we've experienced the full amount of time. But that time can be tweaked and distorted depending on where you are. It's not just the perception. It's the actual simultaneity and duration of the events themselves. All are affected. So Blargle's perspective is not just some wank-off thought experiment. Blargle's perspective, BECAUSE IT IS EQUALLY TRUE, shows that time is as fluid as space. (that doesn't even mean anything!) It shows that our perception of events and simultaneity is flawed, because we regard them as absolutes. It also shows that events that we would consider in our future, in some sense already occurred, because a simple change of perspective can condense them into the present, in an actual, real sense.

None of those things are absurd. Please read up on things before calling into question actual, demonstrated, principles of relativity. This is getting wearisome.

Er, just to be clear, are you saying that a strategically placed observer can see into my future? Because the last thing I bolded certainly seems to say so. I dunno, maybe you're just wording things really strangely and people are getting frustrated.

There is no way for information to be transmitted faster than light. No one could see into our future. That is why, in my original example on page one, I talked about how the entire phenomenon could only be retroactively compared to other events, after light has taken the time to get to the observer.

Marty81 wrote:

Anyway, I have a quick question unrelated to the current discussion because I forgot: When can two observers A and B agree on the order of two events X and Y?

When they are not moving with respect to one another.

Actually, I think there's more to it than that. I'm not asking about simultaneity, just order. I seem to remember it has something to do with whether certain things are within certain light cones or something.

"Light cones" are the 45 degree cones outside of which events cannot be causally connected. They have to do with the experience of time, but they are descriptive. In other words, they merely help explain the relativistic effects I was talking about. A discrepancy between the order of events as perceived by two observers is caused by the bending of spacetime. Spacetime bends in the presence of gravity and acceleration (gravity is actually indistinguishable from acceleration, but that's another topic). So, if two observers are at rest with respect to each other, and close enough so that their light cones intersect, they will agree on the relative order of events.

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