posted
...So much for the Hawking book I've been reading.
quote: The physics detail and language is very complex, but the fundamental theories are fascinating.
Very true. I understood very little of the detail but I think (I hope) that I get the general idea. Question though: Please forgive my arrogance, I'm really trying not to sound it, but isn't some of this a bit... well, common sense?
It may just be that, as with most brilliant ideas, it seems hard at times to imagine that people could have ever thought otherwise but... Well, my dad used to be a professional photgrapher and the fact that he could never get a shot of a moving object without that haze that comes from the motion would drive him crazy. ...And I know this isn't physics, but I've never really thought of time as individual moments since I started playing around with the idea that one moment is a second moment's past and a third moment's future, hence making it in all three perceived "dimensions" of time at once and that which one you see depends simply upon your own position. ::shrugs:: I know I'm not being very clear with this but I hope you can see what I mean.
posted
Pixie, you are absolutely right about the simplicity of the theory that this budding young physicist came up with.
However, it is man's destiny to complicate things beyond all comprehension and then call it higher learning.
This doesn't mean we should all simplify our lives and hunt with spears and wear animal skins, shunning higher mathematics and physics.
The whole article just seemed to hint at the controvery of contradicting the powers that be of the Physics Community.
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posted
This is interesting. Philosophy and foundations of physics is my main research topic, although I've never done any work on instantaneous velocities specifically. I will have to check this out.
Unfortunately the August issue of Foundations Letters isn't available on the web yet. I'll have to wait till I get back to school to read the paper.
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posted
By the way, foundations of physics is not a field in which you 'discover' something new that supersedes previous discoveries. It is a field of contention, which mainly includes people arguing. I doubt this kid has proven anything conclusive, merely made interesting new points.
He also sounds quite arrogant from the quotes.
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posted
Yeah, it is interesting, but like Destineer I have my reservations.
About a theory being obvious, I was suprised to find out about John Nash's theory of governing dynamics presented in A Beautiful Mind was so recently formalized. Of course groups function best when the comprising individuals are working for the interests of themselves, as well as the group itself.
Did nobody notice this until Nash did?
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posted
Sometimes I wonder if the most recent "breakthroughs" are as much new material as they are old, everyday thoughts we've taken for granted that have just been placed under a new light.
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quote:He also sounds quite arrogant from the quotes.
Aren't all the "great minds" arrogant? I mean, every philosopher I've ever read had a healthy dose of arrogance.
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posted
I don't know if I buy it. It was my impression that his theory was that single moments in time don't exist. If that's true, how is it that calculus works so damn well?
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posted
Speaking of Einstein, I have heard dozens of urban legends, like the one about his dog.
Evidently, he was too preoccupied to remember his bearings during a stroll and would get lost. So the powers that be basically got him a seeing-eye dog that was trained to lead him back to home base. Has anyone heard this one, and if so, is it true?
posted
Interesting. I especially love that this comes from someone outside of academia. It is always possible that this is a load of bull and that the one reviewer is correct in his belief that this work is based on a lack of understanding of basics. I hope this is not the case, however. I love the idea of the interested non-professional coming up with something that all the academics couldn't manage. I think it was a sad day when the powers that be decided that it was impossible to make any contribution to the academic debate unless you have degrees coming out your ear and a spotless pedigree as a member of the orthodox establishment.
I didn't understand all the technical ins and outs of the the argument - although I was able to follow more of it than I expected that I would be able to. The thing I wonder is, how will this effect the orthodox western notion of time as strictly linear, in a one-direction-only sort of way? Does it tend to support it or refute it?
posted
Xavier, my dad, who is a mathematical physicist, says that A Beautiful Mind -- especially the movie, but to a lesser degree, the book too -- greatly oversimplified Nash's work. So much so that it is inaccurate. (My dad tried to explain Nash's actual work to me . . . but I guess I found it so mind-twisting that I have blanked it out. )
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posted
Well yeah, I know he put a lot of work into it and that it involved some serious math, but I thought the general concept was accurate. Maybe not though I guess .
The first thing I thought of when he explained his theory (in the movie) was that animals and humans often show altruism to protect the group, even to the point of sacrificing themselves. I thought to myself that evolutionary scientists explain the behavior as being benificial to the group, even if it doesn't help them pass their own genes on. The idea is that when whole group benefits, the genes of the organism's siblings and other relatives have a chance to reproduce.
Now did the evolutionary scientists come up with this after John Nash did his research? At the end I think it implies that his work was applied to many fields, including evolutionary biology. But this theory seems just so darn obvious to me that it boggles that it was so recently discovered. I mean, the man is still alive.
Makes me wonder what other "obvious" things will be discovered during my lifetime.
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posted
My only exposure to Nash was the movie and as i understood it what was not "obvious" about his work was the math. The basic ideas of what he did may be obvious but he devised the math that explained it and could be used to predict it. Thats what I took from the movie anyway.
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posted
It sounds to me like Lynds is absolutely brilliant. His solution to Zeno's paradox is exactly what one would expect it had to be- a change in the underlying assumptions rather than a clever mathematical trick.
It seems to me that if correct Lynd's theory also precludes time travel of any sort as discrete time intervals don't exist therefore one can hardly go back to visit one.
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posted
Actually to my mind it might make calculus easier. The whole premise of derivatives is that you are taking "the limit" of the tiniest instant of time possible. Instead the "limit" of the instants may be more real than the instants themselves. You don't have to pretend to jump to infintessimally smaller to get there anymore, but just say that the "limit" is real while the "instants" don't actually exist and you are there.
posted
sigh... Rather dispiriting to hear that some grown physicists see a formal statement of the implicitly obvious as 'new'.
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posted
It just doesn't sound that profound to me. We've known since Heisenberg that, once you are dealing with small enough measurements, velocity and position cannot be both measured accurately. If you measure one, you'll have no idea what the other one is. This is because once you "squeeze" a particle into a small enough space (thus knowing it's position), the particle will then "shoot" out who-knows-where. This is because all particles are composed of waves, which can be "squeezed" only at the cost of adding energy to the particle.
This sound a lot like what he is describing.
We'll see what the experts decide on it.
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posted
Andrew, not completely true. If you measure the position of a subatomic particle to exactitude, then it's momentum will be uncertain, within a Planck's Constant of value (said constant being very very tiny, on the order of 10^-34). However, that is not to say that it is completely uncerain.
posted
Another thing that bugs me is that it is not at all a 'consensus view' among physicists or philosophers of physics that instants of time exist. Hawking may hold that view, I'm not sure, but it is a problem that few physicists have opinions about and most philosophers and philosophically-minded physicists are divided on. So to say that Lynds is 'rocking the establishment' is inaccurate, unless his paper contains something beyond what the article describes. He's just supporting one of two existing alternatives.
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I finally got around to reading this paper, and it is extremely disappointing.
The guy basically wrote "there is not a precise static instant in time underlying a dynamical physical process" about thirty times and filled in the remainder of the 13 pages with grammatical errors and presumptive analogies.
There is not a single mathematical derivation in the entire paper. Nor is there really any sort of argument; he merely states his position several times and then describes how it is incompatible with several ideas in modern physics.
Check out this lovely prose:
quote:There is a necessary trade of (sic) between certainty at a time, for continuity through time. Please not (sic) that the explanation provided here and previously throughout this paper is also the correct solution to the motion and infinity paradoxes... originally conceived by the Greek mathematician, Zeno or (should be of) Elea.
posted
Destineer's critique makes me want to read the paper. I was intimidated at first, now I'm prepared to giggle. Reminds me of the scientist who was always getting long,long letters from cranks who had figured out The Meaning of It All. From this experience, he came up with a rule: Madmen write 8 page letters.
Bok, I don't know why I didn't see your error the first time. I hope I haven't misunderstood, especially when you just said I was eloquent on the Christianity/rationality thread
quote:If you measure the position of a subatomic particle to exactitude, then it's momentum will be uncertain, within a Planck's Constant of value (said constant being very very tiny, on the order of 10^-34). However, that is not to say that it is completely uncertain
Bok Heisenburg equation: dp x dx > h / (2 x pi) = Planck's constant / ( 2 x pi )
dp= change in momentum, dx= change in position. So if you measure the position of a subatomic particle exactly, dx=0. Therefore dp=infinity. If you don't get the position precision to zero, just close (smaller than the Planck length, say), then the uncertainty of the momentum is only very large, not infinite. Note also that this is a theoretical limit, actual uncertainties will always be larger. The important thing is momentum and position uncertainty are inversely proportional. Heisenburg review (I needed to be sure): linkPosts: 6316 | Registered: Jun 2003
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posted
Actually, it is a common misconception about the uncertainty principle (so common that even many physicists have it!) that the uncertainty applies to the results of measurement. Actually, the Heisenberg principle refers to uncertainty in our ability to predict the result of a measurement given the wave function of the particle. So if we take a particle with a very narrow, spiky wave function we can be quite sure how a position measurement will turn out, but not very sure how a momentum measurement will turn out.
But once we do measure position (or momentum), we get a precise answer. This is discussed in Griffiths, Intro to Quantum Mechanics, p. 19.
posted
The thoughts that there really is no instant in time except what we subjectively imagine as a part of consciousness, and that no object can ever be precisely identified at any point in time because it is constantly in motion through time, are instantly recognizable as true, and I am amazed it took us homo saps so long to realize such simple things. I am still struggling with the concept that time does not move in any direction; what really is involved is just a sequence of events. I suspect this means that time travel truly is impossible, and those equations that suggest otherwise will have to be revisited.
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posted
Ron, this is science we're talking about. Nothing is 'instantly recognizable as true' -- you have to go out there and do experiments!
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posted
Actually I'd say the heart of this is more an issue of philosophy than science, in which case it would be more accurate to say that it is indeed instantly recognizable as true for some people, but also instantly recognizabe as false for others.
quote:Actually I'd say the heart of this is more an issue of philosophy than science, in which case it would be more accurate to say that it is indeed instantly recognizable as true for some people, but also instantly recognizabe as false for others.
Hmmm... yes and no. Like a lot of phil-science questions, the science is very deeply involved in the metaphysics, and so which theories are successful ought to count as 'evidence' of a sort.
For instance, our best theories of motion (which are supported by evidence) use differential geometry to depict spacetime as a collection of points (possible locations of events). Each of these points has a well-defined location in all three spatial dimensions and in the fourth dimension of time. So if you accept, as the theory indicates, that there are points in spacetime, then you should conclude that moments of time do exist.
It actually comes down to a question about calculus. We know that time is continuous; that's what Peter Lynds takes as the main premise of his 'argument.' So the question is, if time is continuous, can there still be instants? This is the same as asking whether there are points on a continuous line. Calc tells us that there are, so Lynds is mistaken.
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posted
Is it possible that the paradoxes that furnish the boundaries for Lynd's theories are more bound up with linguistics than with mathematics? (Where's Tolkein when you need him?)
For instance, the first paradox listed, the tortoise moving in a 10:1 or 100:1 ratio to a never catching-up faster racer is untrue because the racer does pass the tortoise. Therefore change the language! Since you can't compare apples and oranges, why accept ratios and speed in the same sentence?
Just add the term "per moment of time" to any of the paradoxical conundrums and they all seem to work out. This seems to prove that time does have finiteness.
As an animator for many years I was aware of the pacing and acceleration of things in relation to others. Things vary. They are also cyclical. Why does the spokes of the stagecoach appear to revolve backwards? Because our perception of the relationship of the image to the recurring framecount gives an impression of spinning backwards. Even though it appears to go backwards, it is going forward - both mathematically and in reality. It only appears to revolve backwards because our perception sees a phenomenon which our senses process incorrectly and looks like something else.
I look at this more philosophically, rather than mathematically... I have memories. What I am now is based on what happened in the past. My memories of the past exist in the present and make me what I am today. Without the past there would be no memories. Without the memories there would be no me in the present to grow into the future. If math doesn't handle the process correctly - then change the math.
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posted
"We know that time is continuous"--Destineer. I believe this is unproven physically though accepted as axiomatic by almost all modern physical theories, I could be wrong.
I think a discrete theory of time could be fashioned if the "framerate" was suitably small, probably much less than 10^(-45) sec= 0.(45 zeros)1 of a second.= 1/1(45 zeros) of a second
That would mean we are all like characters on God's roto-scope animation! hee hee
Uh-uhh, here comes the eraser! It was just a guess, Nooooooooooooo!! Attica!, Att.......
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quote:For instance, the first paradox listed, the tortoise moving in a 10:1 or 100:1 ratio to a never catching-up faster racer is untrue because the racer does pass the tortoise. Therefore change the language!
But wouldn't that simply be ignoring the problem. After all, why should we have to change the language? Shouldn't we be able to make sense of the situation no matter how it is described?
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posted
Actually, no. Plain language is highly fallible when trying to describe very detailed or specific phenomena, such as you find in science and math. That's why scientists use numbers and equations instead of words.
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posted
I agrre with what Tres and msakaseg posted. The paradoxes of Zeno remain in the mathematical model, they are not just language paradoxes.
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posted
One can use language to say things that are mathematically impossible, sometimes obviously so and other times not. Two examples: a square circle, and the set of all sets that do not contain themselves. Neither construct exists, yet it is still possible to say them.
Hence math. However, that does not make xeno's paradox any less solvable. Xeno's paradox is completely described mathematically with no problems whatsoever. Similarly for every other "paradox" presented as an example. One of the primary reasons for this is that none of the paradoxes is a physical occurence -- they're all mathematical games phrased as physical occurences. However, that they are all solvable mathematically without invoking discrete "temporal" instances strongly suggests that no such instances are required in the concrete parallel situations -- which can never be truly parallel due to the inexactness of the physical world.
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posted
I think the paradox is simply an example of how a bad model, no matter how sophisticated, cannot describe reality. The paradox uses an ever decreasing unit of measure. It notices that its unit cannot describe reality beyond a certain point. All that proves is that its unit is a poor choice for performing this calculation. WmLambert is correct- Most people think of the word "never" in terms of units of the same size. An endless succession of halves may not reach beyond a certain point, but all that shows us is that these halves are poor choices for units. There are some phenomena where an endless succession of halves really is the best description- RC circuits are an example I can think of, since the capacitor will never completely discharge (at least in the simple model I have learned ). Decay of elements is another example. The difference is that in these situations, the halves are taking place in a descreet period of time- Over such a time half the element will decay, over the next period in time equal to the first half of the remaining element will decay, and so forth. In Zeno's example, the runner would be going through an ever increasing number of halves in a descreet period of time, until it would take an infinite number of halves to get to a certain point in time, and it would be impossible to get beyond that point. That point, coincedentally, is precicely where the runner meets the tortoise.
And totally off topic, I want to bring up the coolest paradox ever. If the Greeks were so smart, they should have come up with this one. Furthermore, the principles behind it are relevant to all sorts of areas in our life today. Here goes: Suppose a new drug is invented to treat a disease. A study is formed to see if it is effective. The study compares a group of people who took the drug with a group who didn't. They find that the people who took the drug recovered 50% of the time, while the people who did not recovered 40% of the time. But then they looked a little closer. They found that 70% of the men who did not take the drug recovered, while only 60% of the men who took the drug did. Further, they found that 20% of the women who took the drug recovered, compared to 30% of those who didn't. So the drug increased the recovery rate for the population as a whole, but reduced it for both men and women.
Any way, the answer is found here.
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posted
well of course its obvious, the greatest theoretical changes always are, its their simplicity that makes them useful. the significance is that they're fundamentally different than what was always assumed to be true.
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). Decay of elements is another example. The difference is that in these situations, the halves are taking place in a descreet period of time- Over such a time half the element will decay, over the next period in time equal to the first half of the remaining element will decay, and so forth. In Zeno's example, the runner would be going through an ever increasing number of halves in a descreet period of time, until it would take an infinite number of halves to get to a certain point in time, and it would be impossible to get beyond that point. That point, coincedentally, is precicely where the runner meets the tortoise.
