Why is Time a One-Way Street?
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Leonard Susskind June 26, 2013 Anyone can see that the past is different from the future. Anyone, that is, but theoretical physicists, whose equations do not seem to distinguish the past from the future. How, then, do physicists understand the "arrow of time" — the fact that the past and future are so different? Leonard Susskind will discuss the paradox of time's arrow and how physicists and cosmologists view it today.
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Not sure he addressed the topic. Why not doubt the big bang at least to the extent that it is still banging (and increasing at that). All the space that is being created everywhere is our experience of time. Time should be gradually ticking faster. The arrow of time has to do with the nature of the creation of space. Perhaps with each plank unit of space that is created we experience one plank unit of time. I'm sure I could fill a lecture with such a theory and not get so far off topic.
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The usual progression of events, and time itself may be two quite separate things. That is, although events seem to follow one after the other (moving toward the future), the "time" for them to take place in is unfolding (flowing) from the future through the present and into the past. Picture a reel to reel tape recorder. The unrecorded tape (future) passes through the record head (present) and onto the take-up reel (the past - history). Time in itself may well "move" in such a manner.
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Besides being real, time can be complex. Nahin (An Imaginary Tale...) explains how the equations of motion of a man and a bus tells us if the man can catch the bus. This is done by interpreting complex components of time, that explains if the man can catch the bus or not. In doing so he explains how complex time maybe interpreted as indicating space !!!
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But Boltzmann was right - so far as we know, there seems to have been, and in most statistical probability, there WAS only one Boltzmann brain, in the then-known universe.
Same goes for YOUR brain: so far as we know, there seems to be, in a statistical probabilistic sense, only ONE of your brains in the known universe.
Same goes for my brain. -
Time is a miraculous material measurement of our short lifetimes, with a great need to learn of our greater spiritual reality.. Spirituality is timeless and an enlightened person, educated or uneducated, can enjoy the timelessness of that other dimension..
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This is one of the best lecture you can watch on youtube.
I've learnt alot. Thanks Lenny! -
When ppl learned to measure things, time was one of them. Later they divided time into smaller units of measures. This way ppl learned to sense proceeding time when earlier everything happened "now". Time is two things: 1. a human can experience time (ie. one sees an object moving from A to B) 2. measure (clock is based on earths rotation)
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That's not Leonard Susskind !!!
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OK, for as long as I've followed cosmology Hubble's constant made no sense to me. It only makes sense that galaxies farther away are travelling faster as they are further back in time and haven't slowed as much as the ones closer to the observer. So how does that prove the universe is accelerating?
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This was an interesting lecture on how to reason from the premise of the weak anthropic principle. But what if the weak anthropic principle explains nothing? And the strong antrhopic principle explains why?
It's seems odd that we should have to, literally, make things up (like m-theory) just to satisfy a weak anthropic interpretation of cosmology. -
Nice complement to Sean Carroll's excellent discussion of this.
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Time passes at different rates for different observers. The universe is a vast, ancient sphere from our point of view, but it's a young pancake for a primordial photon. How long does it have to wait for one of Lenny's bubbles? Does it perceive its disk universe to be expanding? And what's the speed of time?
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I don't quite get why ONE single brain would be more likely than many...
The "many" property allows for gradual improvement through evolution and/or cooperation through time....
(in the same way that a child is more likely to be born with a couple of parents than with just one parent!) -
The explanation is circular. He is using time (a dynamic model with change, motion, interaction, cause and effect) to define why there is time. The problem is motion, change and interaction require time to already be defined.
The vortexes which he is proposing as the cause of time, were put into motion by an event in their past, so they already depended on time.
To define time without circular logic, you would need to use a static 4 (or more) dimensional model. -
Is there any reason why the asymmetry of new universes wouldn't itself eliminate the possibility of the Boltzman Brain in the expanding and bubbling scenario? It seems to me if there as a mechanism for the generation of a new universe, and only new universes with certain qualities can result in human life (and thus no Bolztman Brain scenario would occur because that universe wouldn't actually lead to a single brain), then we would "be there" and no longer be "stuck"?
There are plenty of planets out there. Likely some of them have life on them, and there may be many types of life, but we can be confident that many more planets will have life that starts out simple with bacteria and the like and then develop into complex things with brains than there are planets that start out with things with brains. -
All very interesting theories - my take is that time as we experience it is not the cosmological time, but requires a body consciousness to be experienced. Outside of consciousness all bets are off, time can go in any direction or speed. The reason the experience of time needs a body is, that in a living body the arrow of thermodynamics is reversed and the body is constantly renewing itself from the center and eroding at the outside until death. This is the only reason we experience time as linear...
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time is just a human concept to organize the unfolding of events, in my opinion.Maybe its a flaw of the mind, and not something that exists.
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So it comes down to a model of the universe that requires an disequilibrium between 3 space-time and 3+ space, providing vortices (or in modern terms vortexes) to form. Interesting thing, I just made a video on this that includes the role of gravity in the vortices cosmology, called "What is Inertia"
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There are no new dimensions curled in on themselves because if there are, they unwind in the same 3D Euclidian geometry space with 6 degrees of freedom. The extra-dimensions are always perpendicular to the previous ones. How I see it is that there are extra-dimensions but they are in different frequencies like 3D realities superimposed on other 3D realities occupying the same space like a multilayered onion one on top of each other like radio TV frequencies. Again science chooses to ignore metaphysical information.
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he is the best:)
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