How do we know our laws of physics are correct?

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SUMMARY

The discussion centers on the validity of our current laws of physics and how we ascertain their correctness. Participants assert that while laws like the second law of thermodynamics are well-supported by experimental evidence, they are not universally correct in all circumstances. The conversation emphasizes that laws are validated within specific domains, and improvements to these laws are expected as scientific understanding evolves. The reliability of physics is reinforced by practical applications such as GPS technology and space exploration, which depend on these laws for accurate predictions.

PREREQUISITES
  • Understanding of scientific methodology and experimental validation
  • Familiarity with classical physics concepts, particularly Newtonian mechanics
  • Knowledge of thermodynamics, specifically the second law of thermodynamics
  • Basic grasp of relativity and its implications on classical physics
NEXT STEPS
  • Research the implications of the second law of thermodynamics in various domains
  • Explore the differences between Newtonian physics and Einstein's theory of relativity
  • Investigate the concept of time in physics and theories surrounding time reversal
  • Study the role of experimental evidence in validating scientific laws and theories
USEFUL FOR

Students of physics, educators, researchers in the field of science, and anyone interested in the foundations and evolution of physical laws.

  • #31
Actually, we had a huge revolution recently, that concluded that the "Law of Conservation of Mass/Energy" is incorrect. The violation is that the universe seems to be expanding at an increasing rate. There is currently no way to reconcile this with the conservation law. An invisible source of mass/energy might work. But currently the understanding is that the expansion of the universe will increase its mass/energy by huge amounts--another few universes of mass wouldn't be enough to balance things. (The vacuum energy is more than enough.)

The second result is recent and much more subtle. https://physicsworld.com/a/dark-energy-emerges-when-energy-conservation-is-violated/ A QM model where energy is not conserved allows for the energy "lost" on a small scale to create the Cosmological Constant, even though the energy conservation violations are difficult or impossible to see on even a solar system scale.

Will a "Theory of Everything" eventually have a conservation law? Don't know. My guess is that just like adding mass as a result of nuclear physics, the true conservation law will have at least one more term.
 
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  • #32
eachus said:
Actually, we had a huge revolution recently, that concluded that the "Law of Conservation of Mass/Energy" is incorrect. The violation is that the universe seems to be expanding at an increasing rate. There is currently no way to reconcile this with the conservation law.

I'm not convinced. My understanding was that the issue simply wasn't settled yet and I haven't heard anything about a consensus on the subject.

eachus said:
The second result is recent and much more subtle. https://physicsworld.com/a/dark-energy-emerges-when-energy-conservation-is-violated/ A QM model where energy is not conserved allows for the energy "lost" on a small scale to create the Cosmological Constant, even though the energy conservation violations are difficult or impossible to see on even a solar system scale.

Note that this model is very speculative and currently has little to support it over other models.
 
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  • #33
eachus said:
Actually, we had a huge revolution recently, that concluded that the "Law of Conservation of Mass/Energy" is incorrect. The violation is that the universe seems to be expanding at an increasing rate.
Conservation of energy is valid at less than cosmological scales, as centuries of experimental evidence shows. None of the cosmological results change the non-cosmological evidence validating the conservation of energy.
 
  • #34
There's a famous syllogism by Bertrand Russell:

Bread is a stone
Stones are nourishing
Therefore bread is nourishing

The syllogism is supposed to illustrate that a theory can be valid even though the premises themselves are false. So, the postulates of a theory may lead to predictions that are borne out by experiment even if the postulates are not 'correct' (in the universal way the OP refers to). There is no way to tell whether a theory is universally correct.
 
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  • #35
Science evolves. That's what makes it interesting after all. If we knew all the laws from the start of written history (some around 10000BC) it would just be so boring, there would be no evolution.

The evolution of science involves (in my opinion) taking laws that are approximately correct in some domains (the error of approximation is so small in these domains that cannot be experimentally tested, for example Galileo transformations are correct for all domains with velocities <5% of speed of light) and extending them to new domains where the error of approximation is much bigger. So we have to evolve the previous known laws in order to make the error of approximation again small in the new domains. But we can't be sure whether the newly evolved laws are again a very good approximation or they are the absolute correct laws of the universe, the newly evolved laws maybe someday will have to evolve again to match new experimental data from new domains.
 
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  • #36
TheQuestionGuy14 said:
Sorry, I meant correct as in, are they just correct for now,
Of course they are. Our successful level of technology demonstrates that. What more could you want?
Recent developments in Physics have allowed more advanced technology.
 

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