Is World Year of Physics ended ?
31 Dec 2005 17:10:48 UTC
Topic 190481
(moderation:
The impossibility of deciding decisively in mathematics,e.g. determining the accuracy of a theorem, or in physics,when it talks about the particles,precisely about the fundamental phenomenum (corpuscle or wavelike), displays the limits of physics,often computed, for the cognition.The limits which partition the reality and make absolutely impossible to go beyond : for example the constancy of Planck (6/625 x 10 -34 j/second),being the smallest amount of energy in our physical world (the smallest"intelligible mecanical motion").So other absolute limits around the intelligible world are created,e.g. the ultimate length (Planck length) and the ultimate time (Planck time).
In this manner we notice that the newest discoveries in Physics, join the circle of revelation of Metaphysics. When Einstein, the last classical physicist,believed that the Universe and the Truth are knowledgeable, the Quantic theory says that the Truth, not knowledgeable, is hidden behind the Veil and is condemned to remain behind it.
With the Quantic theory , a new field about the Universe , fundamentaly different,displays itself. Now the question is , what we can find beyond all of this ?
Ariane
Is World Year of Physics ended ?
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Why we can rather say that something exists than it does not ? Why Universe began its genesis? Not any physics law based on observation give some response, but at the same time these laws let us describe precisely what happened at the beginning,e.g. 10 -43 seconds after the Big Bang : an incredible minuscule time. How from infinitely minuscule,have been born the infinitely magnified and how the whole Universe and its hundreds thousand million galaxies, emerged from a microscopic "Vaccum" ? What is the generatrix of this tremendous cosmic scenery which within a total mystery is amplifying between two "Infinity" ?
The mass and the temperature of this primordial Universe take incredible dimensions, unintelligible for human brain : 10 32 degrees, the limit of the ultimate heat, beyond which our physics collapses.
Within these fractions of thousand millionth of second, it passes something much more than within the thousand million years after that. Perhaps this effervescence of the beginning is more like a sort of Eternity, because if intelligent creatures could live in these primordial era of Universe, would certainly feel the time spent between each event somhow eternal. Why ? Because the huge "compactness" of events would necessarily claim the "obliquity" of the length of time.
In Quantum Physics, Time & Space being subjective, are pure Idea .......
Ariane
The arrow of Time
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The arrow of Time
When we try unifying gravity and Quantum Mechanics, we encounter necessarily the concept of "ambiguous" time. The ambiguous time is in a way similar to spatial directions. If we move toward north, we can turn back and take the direction of the south. In the same manner by moving forward in ambiguous time, we should be able returning back and reaching our previous position. That means in the ambiguous time there is not such an important difference between advancing and moving back. On the other hand, while observing the "real" time, we notice the difference between the two directions of forward and back . Where is the "source" of this difference between the past and the future ? Why we remember the past and not the future ?
Ariane
Anti-Matter Earthly matters
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Anti-Matter
Earthly matters are basically constituted of protons and neutrons, and these ones of quarks. It doesn't exist anti-protons and anti-neutrons made of anti-quarks, of course apart some units created by physicists in huge accelerators of particles. Nowadays, because of the cosmic rays , it has been demonstrated that this principle is applicable about the whole matter of our world, that means excepting some pairs of particles and anti-particles created in collision of high energy, we will not find any anti-proton and anti-neutron. If , in our galaxy , there existed vast zones of anti-matter , we might expecting many radiations issued from the boundaries between matter and anti-matter zones . Because there would be abundant particles in collision with their anti-particles, exterminating each-other and creating radiations of high energy ...
Ariane
The arrow of Time Ariane
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The arrow of Time
Ariane the discussion I have found most useful starts by dividing time into three categories. The first is psychological time or time as we experience it in our day-to-day lives. This is the hardest to define and can be highly variable depending circumstances. The second category is thermodynamic time which describes things like melting ice and gas escaping from a balloon. Lastly there is physical time this is the time of atomic clocks, special relativity and most quantum theories.
Physical time is by-directional you can run it forward or backwards at will. It is important to note that in the case of physical time we keep track of everything.
In thermodynamic time we give up that absolute knowledge and replace it with statistics. If what ever we are studying never changed then there would no difference between physical time and thermodynamic time (you could even say that time has lost its meaning). However if we drop an ice cube into a glass of water or release the stem of an inflated balloon we have split time into two unmixable chunks before and after. Repeated experiments will show you that left to them selves the ice cube never reforms and the balloon never re-inflates. So experiment tells us that thermodynamic time is uni-directional. Theory states that this is not precisely true but it is rather that we don’t have enough time to actually see either reversal take place (and even longer to see both happen together). It should be noted that this applies equally to classic and quantum systems.
Too round the discussion off it is thermodynamic time rather then physical time that governs most what we perceive happening in psychological time. So psychological time usually is perceived as uni-directional.
If you are looking for a more detailed account I recommend the book The Physics of Time Asymmetry by P.C.W. Davies
RE: The arrow of
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You seem to forget biological time, which makes us grow older and eventually die, geological time starting with the Big Bang and is not reversible. But I suspect that the irreversibility of time in the microscale has something to do with the "reduction of the wave packets". See e.g."Shadows of the mind", by Roger Penrose.
Regards.
Tullio
It's true that I didn't talk
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It's true that I didn't talk about the three arrows of Time : the thermodynamic,the psychological and the cosmological ones,because I was obliged mentionning the principle of order and disorder or regularity and irregularity in Universe.Given the psychological arrow is determined by thermodynamical one and they have necessarily the same direction, if we accept the infinity of Universe, we notice that these two arrows throughout the history of the World, don't follow the same direction. Despite of this fact , these arrows are unidirection just when the conditions are favorable for the developement of intelligent creatures able to ask such a question.
The second principle of thermodynamic is issued from this reality that the number of irregular positions are much more than the regular ones. A broken glass on the floor was a perfect glass on the table,e.g. in its regular position, but broken and on the floor shows its irregular position, we can easily go through the perfect glass in the past to the broken one in the future, but the inverse is impossible.
Talking about the memory of human being is very difficult because we don't know exactly how it functions.
The classical theory of general relativity had anticipated its faintness, because with the increase of the Time-Space Curve, the impact of Quantic explanations becomes more important and the classical theory give us no more satisfactory explanation of things.......
Ariane
tullio: I would consider
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tullio:
I would consider biological time a subset of thermodynamic time. Geologic time or cosmological time has elements of both thermodynamic and physical time. There may discussions wherein it helps to define these extra catagories I don't think they are of any assistance when discussing the arrow of time.
RE: tullio: I would
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I accept your point about cosmological and geologic time. I am not so sure about biological time. According to the second law of thermodynamics entropy should increase in a closed system. But biological evolution goes into the contrary direction, that is towards living systems of greater complexity. I don't think you can explain evolution with thermodynamic ideas. As a matter of fact, you can't even describe a computer within classical thermodynamics. It is simply a heat producing machine.
Tullio
tullio: Does life exist in a
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tullio:
Does life exist in a closed system? Maybe if we include the Sun but in that case you need to examine the entropy produced by the Sun. If we accept the standard model then four protons become a Helium nuclei some neutrinos and gamma rays. At this point we already have more particles than we started with (at least one neutrino and gamma ray for each proton that became a neutron) and most of them no longer gravitational bound. Then further consider how a mega-electron volt gamma decays into hundreds of thousand photons with energies in the range of 10 electron volts or less by the time the energy escape from the surface of the Sun. Life on earth captures only a minuscule portion of that output and delays it a bit.
We can apply thermodynamics to computer coherently if we look at the information input, output and lost a typical computation rather than heat. It turns out computers are usually extremely inefficient in thermodynamic engines.
There are all kinds of seeming exceptions to the three category idea. Reading Davies’s book has convinced me he covered them fairly well. A significant portion of his book is devoted to defining when his ideas are inapplicable.
Ariane:
I am not sure what you mean by Quantic I have been assuming quantum theoretic. Please correct me if I am wrong.
Mark, you are right, I meant
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Mark, you are right, I meant rather quantum theory and Quantic was just a sort of grammatical innovation i did because i wanted avoid using quantum theory. I will explain more later .
Ariane