4 ms·
The point is near the end: "All these challenges arise because of physics’ adherence to reductive unification. Admittedly, the method has a distinguished pedig
by acqq 8y ago
The point is near the end:
"All these challenges arise because of physics’ adherence to reductive unification. Admittedly, the method has a distinguished pedigree. During my PhD and early career in the 1990s, it was all the rage among theorists, and the fiendishly complex mathematics of string theory was its apogee. But none of our top-down efforts seem to be yielding fruit. One of the difficulties of trying to get at underlying principles is that it requires us to make a lot of theoretical presuppositions, any one of which could end up being wrong."
"Instead, many of us have switched from the old top-down style of working to a more humble, bottom-up approach. Instead of trying to drill down to the bedrock by coming up with a grand theory and testing it, now we’re just looking for any hints in the experimental data, and working bit by bit from there."
In practice, both ways to look at the evidence are needed. And in pure science, sometimes a lot has to be done in many different directions before some of non-obvious directions bear fruits. One of big dangers is inventing the experiments that will surely "confirm." The big insights come also when something expected by the most is not confirmed, like the famous
https://en.wikipedia.org/wiki/Michelson%E2%80%93Morley_experiment https://en.wikipedia.org/wiki/Michelson%E2%80%93Morley_exper...
Without these experiments Einstein wouldn't be able to invent General Relativity. The popular culture talks too much about Einstein but sadly doesn't understand and hardly even knows Michelson.
https://en.wikipedia.org/wiki/Albert_A._Michelson https://en.wikipedia.org/wiki/Albert_A._Michelson
His experiment, from the end of the 19th century, is also the basis of the LIGO experiments that just recently confirmed gravitational waves:
https://www.ligo.caltech.edu/page/ligos-ifo https://www.ligo.caltech.edu/page/ligos-ifo
"Although much more sophisticated, at their cores, LIGO's interferometers are fundamentally Michelson Interferometers, a device invented in the 1880's."
The 1880's experiments didn't "confirm" what was "expected" but they are one of the most impressive science success stories, looking from what we know now.
Of course, LIGO itself is a technological marvel compared to what was possible in 1880, and we should celebrate all the advanced experiments where our reach extends. Not "confirming" expected can be even much bigger story, even if it disappoints those whose "pet" "expected" theory is not confirmed.
- v_lisivka 8y agoSo, LIGO experiment confirmed that Einstein theory is wrong. Right?
- misnome 8y agoI’m not sure if you are referring to something specific in that post but no, quite the opposite - LIGO confirmed Gravitational waves, predicted by Einstein’s general relativity. The Michelson-Morley experiments were a failure in that they didn’t find what they were looking for (Aether), but relativity came out of trying to understand that “failure” (rather, the null results of the experiment - calling not seeing something you expect a failure is an oversimplification)
- v_lisivka 8y agoLook, we have 3 very similar experiments (Michelson-Morley, Stagnac effect, and LIGO) and 3 very different and complex interpretations of their results while 1 simple explanation can fit them all. I must note that Michelson-Morley didn't find Aether _wind_, which is expected if you take in account Sagnac effect.
- the6threplicant 8y agoMaxwell's equations show that the speed of light is invariant in all inertial reference frames. In other words, the speed of light is the same no matter what speed you are going. This was a bigger inspiration to Einstein than the MM experiments.
- acqq 8y agoWithout the experiment the equations are just some symbols that can but don’t have to have any connection to the reality.
- v_lisivka 8y agoSpeed of sound is invariant in all intertial reference frames. Speed of sound of supersonic plane is constant. Speed of sound in supersonic plane is constant. Air does not exists: it's contraction and expanding of space-time, not an air. (Joke)
- lloeki 8y agoKind of tangential but this reminds me of Feynman: > It doesn't matter how beautiful your theory is, it doesn't matter how smart you are. If it doesn't agree with experiment, it's wrong.
- auslander 8y agoI have a better one :) "You have to worry about your own work and ignore what everyone else is doing" - stepsandleaps.wordpress.com/2017/10/17/feynmans-breakthrough-disregard-others/
- gwern 8y agoThe funny thing about that quote is that Feynman ignored it all the time. Back during the post-WWII explosion, Feynman would get told about some exciting new result and regularly said that the result was wrong because it contradicted theory and was experimental error. And it usually was error. A lot of those anecdotes in his oral history: https://www.aip.org/history-programs/niels-bohr-library/oral-histories/5020-1 https://www.aip.org/history-programs/niels-bohr-library/oral...
- marcosdumay 8y agoExperimental data comes with confidence levels. There's no point in being excited at low confidence extravagant data. This does not detract from his phrase in any way.
- gwern 8y agoYes, it does. He didn't say, "it doesn't matter how beautiful your theory is, unless of course, it's sufficiently beautiful that it has high posterior probability such that you will dismiss an indefinite but potentially large number of experiments showing it's wrong until enough experiments have been done that you have to admit that it's wrong because it disagrees with them". Of course, Feynman was right to dismiss those experiments. It's his quote which is cute, oversimplified, and wrong. It's Duhem-Quine all over.
- DoctorOetker 8y ago
- skolemtotem 8y ago> The popular culture talks too much about Einstein but sadly doesn't understand and hardly even knows Michelson. I'm not sure if that's true. At the very least, his story is given a lot of attention in my country's high school physics syllabus.