[sago]

"Defy the known laws of physics" is thrown about a lot. But usually means "If what we are seeing is a self-contained vehicle, it exceeds reasonable assumptions about manoeuvring envelopes for known technologies."

The "laws of physics" are pretty wide. There are many kinetic phenomena, entirely consistent with them, whose dynamics can't be filmed even at thousands of frames per second. There are all kinds of potential optical and electromagnetic effects (whether natural or intentional) that could show essentially arbitrary scale and motion.

"Def[ies] the known laws of physics", is a good sign your imagination is too narrow, or your understanding of physics too small.

[hermitdev]

Not trying to be pedantic, but I think this fits well with your comment.

To the best of my knowledge, the only accepted laws of physics relate to the 3 laws of thermodynamics. Everything else is still considered a theory (to the best of my knowledge), even if the theory works really damn well (for instance relativity is still considered a theory).

I know there are accepted "laws" in other fields related to physics, such as Ohm's or Kerchov's laws in electrical engineering, but I don't think these are generally accepted scientific laws, more generally accepted as engineering laws where for nearly all cases for engineering, they apply to a sufficient accuracy to produce products that are sufficient.

[paulmooreparks]

You're confusing the colloquial meaning of "theory" with the scientific meaning. A scientific theory has been tested repeatedly and can be reasonably relied upon to make predictions (see relativity and GPS, for example). The colloquial meaning of theory is more accurately called a hypothesis.

[hermitdev]

I'm not, actually. If relativity were a law, we'd presumably have unification with quantum mechanics. But we don't. Relativity works really well (well enough) in an enourmous number of areas, but not all and completely breaks down at the quantum level.

And, it only takes a single counterpoint to disprove a theory. Hence theories are signifcantly harder to prove than disprove.

What you're referring to as laws are theories that work well enough in some circumstances that needing something better isn't needed. Such as relativity to implement GPS. Newton's theorems in Principia Mathematica are generally good enough for most day to day type stuff. E.g. we dont need to involve Relativity to understand the physics being acted upon a car (thats not a Tesla roadster launched into space).

Science isnt much about coining laws. It's more about obtaining an ever more correct model of reality, and as you say, make (reasonably accurate) predictions.

[mehrdadn]

> To the best of my knowledge, the only accepted laws of physics relate to the 3 laws of thermodynamics.

How about conservation of momentum?

[chopin]

Following Noether's theorem conservation of momentum relies on translational symmetry of space which we assume but have no proof for (other than measurements of conservation of momentum). In so far it is theory territory.

Thermodynamics on the other hand relies only on effects of large numbers (of hard balls) with no further assumptions. In so far I can understand the GP assertion although I am reluctant. You put in the hard ball assumption (particles can exchange energy) which may put it in theory territory. As well the laws hold only for equilibrium situations which can be reached in (sufficiently dense) baryonic matter but maybe not for non-baryonic matter.

[mehrdadn]

> "Def[ies] the known laws of physics", is a good sign your imagination is too narrow, or your understanding of physics too small.

I don't know but I would assume they are usually referring to conservation of momentum being violated, rather than something like the 2nd law of thermodynamics or the Heisenberg uncertainty principle. Which is pretty easy to see unless you have reason to believe there is something rather crazy happening that you cannot see (like I imagine a neutron being emitted at >99% of the speed of light to cancel some change in momentum that you otherwise can't explain).