Consulting only my memory: I believe it’s the special case of a larger equation describing an object’s total mass-energy, something like E^2 = [something based on the rest mass of an object] + [something based on the object’s momentum], and when the object’s velocity is 0, it becomes something like E^2 = m^2 c^4 + 0, which simplifies to E = mc^2.
I believe it’s correct—let’s say at least 99.9% confidence that this is what special relativity says, and 99% confidence that special relativity is accurate in some broad range of scenarios (though there’s probably a “more correct” theory that will replace relativistic quantum electrodynamics eventually). I believe it’s useful for physicists—”it” being the full E^2 = … equation. If you mean the E=mc^2 special case… I think it may still somewhat useful for nuclear reactor engineers, because a noticeable amount of mass evaporates when nuclear fule is spent. Maybe some other specialized engineers.
I believe the equation itself because I’ve seen statements to that effect (some more explicit than others) in a few different physics books and Wikipedia, and have never encountered a reason to doubt them in this subject.
How much does it concern you that, previously in human history, “every book”/authority appears to have been systematically wrong about certain things for some reason? How many of these authors have directly experimented in physics, compared to how many just copied what someone else/ a small number of really clever scientists like Einstein said?
I guess maybe that accounts for the 1% doubt you assigned.
Some things are easier to test than others. Also, some phenomena are simpler than others. In social sciences, experiments involve what is effectively a lot of human labor (hence expensive and slow), and observations tend to be very subjective (hence imprecise when you try to aggregate anything), and humans have a lot of complexity you can’t subtract out while keeping them alive and free. Also, there are political considerations / ideology that impinge on social science and economics results. In physics, there is mainly just the potential for politics about supporting an individual physicist’s career and prestige… and the more funding there is, I guess the more danger there is of that. (String theory seems to be an example in which predictions aren’t really testable, and some people do make a strong case that career politics has unduly influenced that subfield.) But the danger of corruption seems smaller, at least. Results from enormous supercolliders that cost zillions of dollars—sure, those are harder to verify. But there’s plenty of physics that’s much cheaper to test.
Einstein himself made mistakes. He added an arbitrary “cosmological constant” into his theory of general relativity, and later called it the biggest mistake of his career (though, ironically, I think more evidence has arisen since then that points to something vaguely resembling it—”dark energy”). He also needed to have his front door painted red, else he would wander into the wrong house. The Millikan oil drop experiment is a famous case of stupefaction… but I think it’s well-known in physics because it’s rare.
I’ve heard that quantum electrodynamics is one of the most heavily verified sciences there is, with the theory matching observations out to something like 8 decimal places. Now, we know that QED is “wrong” in the sense that it doesn’t account for gravity, so there will hopefully be some future theory that replaces it like general relativity replaced Newtonian mechanics. But I believe there’s a wide range of scenarios in which gravity doesn’t matter much (or can be accounted for in a crude fashion), in which observations match theory, and in that sense I’m confident QED is “correct”.
I’ve heard that all the companies that use satellites need to take general relativity into account for accurate timekeeping (which is important for, I imagine, purposes like triangulating a signal). If that’s true, it would be unlikely that they’d all make the same mistakes and believe the same incorrect theory. I’m pretty satisfied with that as proof that general relativity is “correct” (within a reasonable set of scenarios, to a good degree of accuracy).
Most of the uncertainty about the above is “have people been lying to me?” or “is my memory screwed up?” rather than “have the practitioners screwed up?”.
Consulting only my memory: I believe it’s the special case of a larger equation describing an object’s total mass-energy, something like E^2 = [something based on the rest mass of an object] + [something based on the object’s momentum], and when the object’s velocity is 0, it becomes something like E^2 = m^2 c^4 + 0, which simplifies to E = mc^2.
I believe it’s correct—let’s say at least 99.9% confidence that this is what special relativity says, and 99% confidence that special relativity is accurate in some broad range of scenarios (though there’s probably a “more correct” theory that will replace relativistic quantum electrodynamics eventually). I believe it’s useful for physicists—”it” being the full E^2 = … equation. If you mean the E=mc^2 special case… I think it may still somewhat useful for nuclear reactor engineers, because a noticeable amount of mass evaporates when nuclear fule is spent. Maybe some other specialized engineers.
I believe the equation itself because I’ve seen statements to that effect (some more explicit than others) in a few different physics books and Wikipedia, and have never encountered a reason to doubt them in this subject.
Thanks for your thoughtful answer.
How much does it concern you that, previously in human history, “every book”/authority appears to have been systematically wrong about certain things for some reason? How many of these authors have directly experimented in physics, compared to how many just copied what someone else/ a small number of really clever scientists like Einstein said?
I guess maybe that accounts for the 1% doubt you assigned.
Some things are easier to test than others. Also, some phenomena are simpler than others. In social sciences, experiments involve what is effectively a lot of human labor (hence expensive and slow), and observations tend to be very subjective (hence imprecise when you try to aggregate anything), and humans have a lot of complexity you can’t subtract out while keeping them alive and free. Also, there are political considerations / ideology that impinge on social science and economics results. In physics, there is mainly just the potential for politics about supporting an individual physicist’s career and prestige… and the more funding there is, I guess the more danger there is of that. (String theory seems to be an example in which predictions aren’t really testable, and some people do make a strong case that career politics has unduly influenced that subfield.) But the danger of corruption seems smaller, at least. Results from enormous supercolliders that cost zillions of dollars—sure, those are harder to verify. But there’s plenty of physics that’s much cheaper to test.
Einstein himself made mistakes. He added an arbitrary “cosmological constant” into his theory of general relativity, and later called it the biggest mistake of his career (though, ironically, I think more evidence has arisen since then that points to something vaguely resembling it—”dark energy”). He also needed to have his front door painted red, else he would wander into the wrong house. The Millikan oil drop experiment is a famous case of stupefaction… but I think it’s well-known in physics because it’s rare.
I’ve heard that quantum electrodynamics is one of the most heavily verified sciences there is, with the theory matching observations out to something like 8 decimal places. Now, we know that QED is “wrong” in the sense that it doesn’t account for gravity, so there will hopefully be some future theory that replaces it like general relativity replaced Newtonian mechanics. But I believe there’s a wide range of scenarios in which gravity doesn’t matter much (or can be accounted for in a crude fashion), in which observations match theory, and in that sense I’m confident QED is “correct”.
I’ve heard that all the companies that use satellites need to take general relativity into account for accurate timekeeping (which is important for, I imagine, purposes like triangulating a signal). If that’s true, it would be unlikely that they’d all make the same mistakes and believe the same incorrect theory. I’m pretty satisfied with that as proof that general relativity is “correct” (within a reasonable set of scenarios, to a good degree of accuracy).
Most of the uncertainty about the above is “have people been lying to me?” or “is my memory screwed up?” rather than “have the practitioners screwed up?”.
Actually, the best tests of QED are correct to 13 decimal places, see the electron’s g in https://en.wikipedia.org/wiki/Anomalous_magnetic_dipole_moment , or 10 if you only consider g-2 (which is much smaller than g).