Conflict? Releativiy and Quantum

Discussion in 'Astronomy, Exobiology, & Cosmology' started by Tristan, Jul 5, 2001.

  1. Tristan Leave your World Behind Valued Senior Member

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    What is the conflict between the theorys of Reletivity and Quantum?






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  3. Crisp Gone 4ever Registered Senior Member

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    No conflict.

    Hi Tristan,

    There is no immediate conflict between both theories.

    The "classical" (Heisenberg/Schrodinger) theory of Quantum mechanics simply assumes that energylevels are low enough to ensure no relativistic effects occur. At higher energylevels, the theory of (special) relativity and quantum mechanics have been joined to form the quantum field theory.

    You're probably hinting at a quantum theory of gravitation though. Also, in principle, there's no problem here (the gravitational field can be quantized in a graviton using quantum field theory). The reason why we don't have a quantum theory of gravity yet is because the mathematics are flawed (infinities show up where they shouldn't, the maths are inconsistent, ...). The idea is there, it's only the mathematical framework that still has to be worked out.

    Bye!

    Crisp
     
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  5. Tristan Leave your World Behind Valued Senior Member

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    no offense at all but put in simpler terms, i'm only 14! But i understand your point!

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  7. Crisp Gone 4ever Registered Senior Member

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    Correction

    Hi Tristan,

    Sorry about the technical mumbo-jumbo, I'll try to explain it in simpler words:

    First, the theory of relativity consists of two parts: the special theory of relativity (started by Einstein in 1905) which describes the bizarre world and all the special effects that occur of particles that go at tremendous speeds: almost the speed of light (we're talking 99,999999999% of the speed of light here). It is important to know that the special theory of relativity explains effects that are only seen at very high speeds (= high energies), and these effects are not noticeable in our everyday live. The second part of the theory of relativity, also named the "general theory of relativity" describes how masses bend space and time (and how this leads to gravity, ...)

    The theory of quantum mechanics as it was originally developped in the 1920's, and because they didn't want to complicate things at first, the special theory of relativity was not included. This basically means that the original theory of quantummechanics just no longer works at very high speeds, simply because the effects of special relativity are not included. Several years after the original theory of quantummechanics had been developed, the theory of special relativity was combined with quantummechanics to (what we now call) the quantum field theory.

    So basically, there was no conflict between the theory of special relativity and quantummechanics. They both complement eachother and have been combined to a single theory.

    Things become more difficult when you want to combine the general theory of relativity (the one that describes gravity) with quantum mechanics. Gravity is what physicists call a field, so if you want to describe it quantummechanically, you would expect that the quantum field theory does the job well. In quantum field theory, fields are "quantized": this means that a field is not spread out in space and exists anywhere, but is represented by a particle (= a quantum of the field). For example: the electromagnetic force is represented by the photon, the nuclear force by the pi-meson (short: pion). The quantum of the gravitational field is called the graviton. Appearantly the quantum field theory doesn't work for gravitons, because if you want to calculate the properties of this particle, you run into all sorts of mathematical problems (properties of the particle are calculated to be infinite, which is not physically possible).

    This is really just a mathematical problem (in order to fix those infinities, you need to use special math tricks). So the idea is there, but the maths isn't at the moment.

    BTW: I am no quantum field expert, anybody with more experience on the field can perhaps correct some errors I might have made in this post

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    Bye!

    Crisp
     

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