Newton's law of gravity has been falsified by classical GR.Hehe. You're the first in this thread who's made that assertion. In what sense is it not valid?
I've never heard this asserted. What I hear is more along these lines:Newton's law of gravity has been falsified by classical GR.
http://en.wikipedia.org/wiki/Newton's_law_of_universal_gravitationGeneral relativity reduces to Newtonian gravity in the limit of small potential and low velocities, so Newton's law of gravitation is often said to be the low-gravity limit of general relativity.
I enjoy rigorous logic. "Philosophy" is when you smoke some hash with your buddy, look at the stars and proclaim "Dude! Do you realize that in 10,000 years the law of Universal Gravitation might not be valid?"I can tell by the way you avoided spending time/energy in this thread
That Newton's gravity is only the weak field slow motion limit of GR means that Newton's gravity has been falsified (doesn't have to be that strong - Newtonian gravity already gets mercury wrong, while GR gets it right).I've never heard this asserted. What I hear is more along these lines:
In other words, Newton is wrong in all gravity fields. The lower the gravity, the less wrong.General relativity reduces to Newtonian gravity in the limit of small potential and low velocities, so Newton's law of gravitation is often said to be the low-gravity limit of general relativity.
I don't completely get this. Newton set out to prove gravity was universal: that all heavenly bodies had gravity. This, he did, by a mountain of geometric proofs that showed that, if they did, we'd see the orbits we actually do see (he didn't know about Mercury, and I don't see how his failure to predict the Mercury thingy invalidates the theory that all heavenly bodies have gravity.) To say he's wrong or has been falsified should mean we've found some masses out there that don't have gravity.In other words, Newton is wrong in all gravity fields. The lower the gravity, the less wrong.
http://en.wikipedia.org/wiki/Newton's_law_of_universal_gravitationNewton's law has since been superseded by Einstein's theory of general relativity, but it continues to be used as an excellent approximation of the effects of gravity. Relativity is required only when there is a need for extreme precision, or when dealing with gravitation for extremely massive and dense objects.
To every purpose, there is a Feynman quote.
It's perfectly OK with me to suggest I'm mistaken, but explain what you think Dave is saying that I don't understand, and rephrase what you said about what the teacher is saying. I couldn't make heads or tails of it the way you put it.I think you are misunderstanding what people are saying to you in this thread(incl. the philosophy teacher, who i don't perceive as attacking valid scientific inferences, but mistaking tentative but valid to the best of our knowledge conclusions for all encompassing truths). DaveC makes good points(as ever)
I would want it not to constitute" an excellent approximation of the effects of gravity". That would make it much clearer.Newton proposed three postulates. Using those postulates, he makes numerical predictions on the outcomes of experiments. The numbers don't match experiment. What more do you want to falsify a theory?
If we don't know gravity (or anything at the same fundamental level) is going to be valid in 10,000 years, then we don't know it will be valid in 10 minutes, either. Strictly speaking, we don't.
Not wishing to be a science zealot I can, therefore, recommend this teacher jump off a cliff at the first opportunity. Because I take her point: I have no definite means of knowing if gravity will be valid when she does.
No, I saw the one where he sweeps equal areas in equal times.
https://www.youtube.com/watch?v=EYPapE-3FRwR. Feynman said:If it disagrees with experiment, it's wrong. That's all there is to it.
Arrogance...I enjoy rigorous logic. "Philosophy" is when you smoke some hash with your buddy, look at the stars and proclaim "Dude! Do you realize that in 10,000 years the law of Universal Gravitation might not be valid?"
"WHOAA! Shut up man! That's TOOO heavy!"
While he clearly is making a mockery, some philosophers can be too far out there to be practical (they might actually be technically correct or make a good point, but again its what I refer to as 'too much paranoia').Arrogance...
Interesting!One thing we know for sure that will remain valid in a 100 years is the TOE - because if it isn't, it's not the TOE! Caveat - unless time exists only up till 99 years from now. The other possible attack on the teacher's statement is the assumption that probability exists - is she a frequentist or a Bayesian?