-1
$\begingroup$

We all know about the discrepancy between relativity and quantum physics at the scale relative to particles. Wouldn't the fact that recent experiments show quantum effects at the macro-scale in some way negate relativity since they're not supposed be compatible? For instance:

Weird Quantum Theory Works in 'Big' Things

Physicists Show Theory of Quantum Mechanics Applies to the Motion of Large Objects

And several others. There have been many such experiments lately. I recall one involving super-cooled semiconductors. Searching Google for "quantum physics macro scale" reveals many such experiments. How can this be reconciled with what are supposed to be two incompatible areas of physics?

$\endgroup$
  • 2
    $\begingroup$ General relativity doesn't predict quantum behaviour at the microscale, either. Why would quantum behaviour at a macroscale disprove it when the formerly microscale behaviour didn't? (If the microscale behaviour did disprove GR, this question is similarly meaningless) $\endgroup$ – ACuriousMind Sep 24 '15 at 0:41
  • 1
    $\begingroup$ I think you may have misunderstood the degree to which there is a problem between the theories. At accessible energies (and in all likelihood for many orders of magnitude beyond) relativity and quantum mechanics get on swimmingly. $\endgroup$ – dmckee Sep 24 '15 at 0:47
  • $\begingroup$ I'm not a physicist by profession so I get that maybe my question isn't going to lead to something groundbreaking but this is why I hate the downvoting of stack exchange. I ask a question that's valid even if my understanding of physics isn't as good as some of the people here and my question get's downvoted. I don't think that's what downvoting is for. It's for questions that have already been answered or that aren't constructive. I could imagine other people asking the same thing. $\endgroup$ – xendi Sep 24 '15 at 1:56
  • 2
    $\begingroup$ I have not voted on this questions, xendi, but I would invite you to take the tour of our fair site. Each exchange sets it's own rules about topicality and the expected style and level. The users of Physics have repeated said they want the focus to be on the kinds of questions that physicists ask. And while not all pop-sci level question meet with disapproval, neither are all well received. In any case, the tooltip on the downvote button reads "This questions does not show any research effort; it is unclear or not useful." $\endgroup$ – dmckee Sep 24 '15 at 2:22
0
$\begingroup$

We all know about the discrepancy between relativity and quantum physics at the scale relative to particles.

No, we do not, at least those of us who have studied particle physics for decades.

Special relativity and quantum mechanics describe particle data with great accuracy. General relativity, due to the extreme weakness of the gravitational constant and the tiny masses of the particles is beyond the pale of measurements possible with particle physics .

How can this be reconciled with what are supposed to be two incompatible areas of physics?

The incompatibility your are referring to is that quantization of gravity is still at the research stage. The need for quantization of gravity appears at cosmological distances, and particularly in modeling the Big Bang. There exist effective field theories that are used in the BB model with quantization of gravity before 10^-32seconds. It is at cosmological scales that the two, general relativity and quantization have to be reconciled.

The most promising research field for quantization of gravity is with string theories, which can accomodate both General Relativity and embed the Standard Model of particle physics. Once a definitive model, based on string theories, is found even this "incompatibility" at cosmic scales will disappear.

Your misunderstanding is based on the word "macro" . Macro for general relativity is on cosmological scales. For GPS to work well we need GR, for problems like a falling apple its effect is too small to be measurable in the lab. The experiments you are talking about are not on cosmological scales.

$\endgroup$
  • $\begingroup$ After reading your answer I then went and did more reading and now realize the problem with my question which makes an incorrect assumption. One thing I don't understand though is your definition of macro-scale as being "Cosmic." To my understand, anything that isn't microscopic or so discrete as say an atom or even higher up as larger than a cell is considered to be macro-scale. For instance, the chair on which I'm sitting is constructed out of macro-scale materials that are made of many microscopic (And smaller) discrete parts as atoms and particles. I was originally referring to particles. $\endgroup$ – xendi Sep 27 '15 at 21:26
  • $\begingroup$ Ran out of space... I was originally referring to particles vs let's say a basketball. $\endgroup$ – xendi Sep 27 '15 at 21:28
  • $\begingroup$ The gravitational constant is so very small that to see any effect of general relativity one has to go at least to planetary sizes, not basket balls. Basket balls are macro for the three other forces. The GPS system needs corrections from General Relativity $\endgroup$ – anna v Sep 28 '15 at 3:46

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.