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Relativity and quantum mechanics.

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Sonic200
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30 Aug 2021, 11:24 am

I have heard that relativity and quantum mechanics can't both be right based on the current understanding of them because they contradict each other.

While relativity and quantum mechanics both do a good job in describing the physical world, they don't do well together.



naturalplastic
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30 Aug 2021, 11:37 am

Yep. Thats what Ive heard. And read. Einstein is good on the macro level. Galaxies and the Universe. Quantum works on the subatomic level. In between...here on the human scale -good old fashioned Newton works well enough.



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30 Aug 2021, 11:41 am

I want to see how far I can follow with my limited physics.

In the past, Bohr seemed a tiny bit accessible to me.

Quote:
The Bohr–Einstein debates were a series of public disputes about quantum mechanics between Albert Einstein and Niels Bohr. Their debates are remembered because of their importance to the philosophy of science, since the disagreements and the outcome of Bohr's version of quantum mechanics that became the prevalent view form the root of the modern understanding of physics.[1] Most of Bohr's version of the events held in Solvay in 1927 and other places was first written by Bohr decades later in an article titled, "Discussions with Einstein on Epistemological Problems in Atomic Physics".[2][3] Based on the article, the philosophical issue of the debate was whether Bohr's Copenhagen Interpretation of quantum mechanics, which centered on his belief of complementarity, was valid in explaining nature.[4] Despite their differences of opinion and the succeeding discoveries that helped solidify quantum mechanics, Bohr and Einstein maintained a mutual admiration that was to last the rest of their lives.[5][6]

The debates represent one of the highest points of scientific research in the first half of the twentieth century because it called attention to an element of quantum theory, quantum non-locality, which is central to our modern understanding of the physical world. The consensus view of professional physicists has been that Bohr proved victorious in his defense of quantum theory, and definitively established the fundamental probabilistic character of quantum measurement.[citation needed]


https://en.wikipedia.org/wiki/Bohr%E2%8 ... in_debates



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31 Aug 2021, 7:55 am

Sonic200 wrote:
I have heard that relativity and quantum mechanics can't both be right based on the current understanding of them because they contradict each other.

While relativity and quantum mechanics both do a good job in describing the physical world, they don't do well together.


It is because there are pieces missing from our understanding, not from a specific error in either one of them. Without those missing pieces, they look like they do not fit to make the universe work the way it does. We likely will not know the full story in our lifetimes.

Theories can have issues but still be valuable for their explanations. Niels Bohr earned his Nobel Prize from his atomic structure theory of how electrons orbit the nucleus of an atom. His theory only perfectly describes what goes on in a simple hydrogen atom. Once the number of orbiting electrons in an atom increases above one, his model shows flaws. They do not typically orbit in perfect circles around the nucleus. The theory is not absolute, but it is the best explanation from that era in time. It is still the best model we have to teach atomic theory to students learning the basics of chemistry for the first time.

Most people think the electrons move purely randomly in an 3-D orbit, but that is not the complete answer. The seeming random movement is why physicists have equations of probability for their orbits. Electrons are acted upon by the particles within the nucleus that direct them in their movement. How they are directed is something that I have been researching for a few years. The key involves the substructure of each particle. If that relationship can be found and proven experimentally, it could undue the Heisenberg uncertainty principle as we know it.



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31 Aug 2021, 8:33 am

Not really.
Special relativity can be totally incorporated into quantum models. It makes formulas lots and lots more complicated but it can be done and it's done when relevant.
For electromagnetic forces, you can introduce relativistics first with Dirac equation, then with fully QED approach. Spontanous generation and annihilation of particles emerges from the equations.
The calculations are pretty horrorous but the agreement between theory and measurements is perfect to the limits of current best measurement precision.

The problem is to "marry" quantum theory with general relativity. It's the current Holy Grail of theoretical physics. The problem is, indeed, these theories start from completely different points and use completely different terms, impossible to translate between each other within existing understanding.
They also work perfectly within regions where they dominate: quantum theory with things of the size of atoms (where we can safely ignore gravity), general relativity with things of the size of planets (where we can safely ignore quantum effects).

Current human knowledge has no idea what happens in Planck scale where both quantum and gravitational effects are expected to be of similar strength. Existing theories, working great elsewhere, collapse in this region. There are probably some yet unknown phenomena, some "new physics".
Current technology is unable to explore these areas experimentally and current theories are lots of mathematics not necessarily connected to any physical reality.
We just don't know what to expect there.


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Sonic200
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31 Aug 2021, 3:01 pm

QuantumChemist wrote:
Sonic200 wrote:
I have heard that relativity and quantum mechanics can't both be right based on the current understanding of them because they contradict each other.

While relativity and quantum mechanics both do a good job in describing the physical world, they don't do well together.


It is because there are pieces missing from our understanding, not from a specific error in either one of them. Without those missing pieces, they look like they do not fit to make the universe work the way it does. We likely will not know the full story in our lifetimes.

Theories can have issues but still be valuable for their explanations. Niels Bohr earned his Nobel Prize from his atomic structure theory of how electrons orbit the nucleus of an atom. His theory only perfectly describes what goes on in a simple hydrogen atom. Once the number of orbiting electrons in an atom increases above one, his model shows flaws. They do not typically orbit in perfect circles around the nucleus. The theory is not absolute, but it is the best explanation from that era in time. It is still the best model we have to teach atomic theory to students learning the basics of chemistry for the first time.

Most people think the electrons move purely randomly in an 3-D orbit, but that is not the complete answer. The seeming random movement is why physicists have equations of probability for their orbits. Electrons are acted upon by the particles within the nucleus that direct them in their movement. How they are directed is something that I have been researching for a few years. The key involves the substructure of each particle. If that relationship can be found and proven experimentally, it could undue the Heisenberg uncertainty principle as we know it.


Well, yes. Newtonian mechanics is still useful in certain situation. It's not perfect however. Relativity and quantum mechanics might turn out the same way in the future. Useful approximations, but not perfect.



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23 Sep 2021, 10:15 am

Sonic200 wrote:
... Newtonian mechanics is still useful in certain situation. It's not perfect however. Relativity and quantum mechanics might turn out the same way in the future. Useful approximations, but not perfect.
That is an apt description of one aspect of science, it relies on many useful approximations, many of which do not work well together -- yet they still work.

Also, science is self-correcting, so scientists may one day reach the goal of a Unified Field Theory.  Until then, our approximations will continue to work just fine.