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Was the orbit of Mercury (or any other astronomical observations) important for the discover of Relativity. My understanding was that experimental impetus for r

Was the orbit of Mercury (or any other astronomical observations) important for the discover of Relativity. My understanding was that experimental impetus for relativity was the Michelson–Morley experiment, which was an in-lab experiment, not an astronomical observation. General relativity was then developed on a purely theoretical basis. That it was able to explain Mercury's orbit was a nice bit of empirical confirmation after the theory was developed. Having such evidence probably helped get the theory accepted faster; but probably wasn't necessary. Almost by definition, a theory that is ultimately useful can be confirmed without need of astronomy. If the theory is useful to do X, then we can try doing X as an experiment and see if it works how the theory predicts. As a secondary point, we could probably get GPS to work even without relativity. The core idea makes just as much sense under any theory of a finite speed of light. When we actually launched a GPS constellation and try it, the engineers would notice that the clocks were drifting for some unknown reason. Some ad-hoc corrections later and the engineers could account for the drift based on empirical evidence, likely with regular re synchronization and recalibration of the fudge factors.

onlyrealcuzzo 5y ago
Good luck finding a $1Tr project without real world evidence - just theoretical models.
- flaburgan 5y ago
  You mean like we do at CERN?
  - jacquesm 5y ago
    You're off by a factor of 1,000.
    - throwawaylinux 5y ago
      How about the Iraq War?
      - Dylan16807 5y ago
        Is not a science project. If you're trying to make a weird point you need to be more direct, and if you're trying to make a political point you're just wasting everyone's time.
        throwawaylinux 5y ago
        Original post didn't specify science project, just project.
        Dylan16807 5y ago
        Even ignoring context it's a huge stretch to call that a 'project'.
      - jacquesm 5y ago
        I fail to see the link between the budget of CERN and the cost of the Iraq war.
  - deleted 5y ago
    [deleted]
fhars 5y ago
No, there was basically no empirical input into the development of special relativity either, Michelson-Morley was already perfectly explained by Lorentz contraction caused by movement of matter through the ether. What special relativity did was solve the purely theoretical contradictions between Newtonian mechanics and Maxwell's electrodynamics (hence the title of Einstein's paper "On the electrodynamics of moving bodies"), reinterpreting Lorentz' math for the description of movement through the ether as transformations of spacetime itself and doing away with the ether.
- Maursault 5y ago
  > No, there was basically no empirical input into the development of special relativity either There is a myth of Einstein that just isn't credible, which is that Einstein, while working as a patent clerk just came up with Special Relativity out of the blue without anyone's input, without the benefit of history. But Special Relativity was in the air. Henri Poincare was already writing about relativity, and so were others in years previous to Einstien's publication. If Einstein hadn't published when he did, someone else would have within a few years at best. Einstein was amazing, also, just a man, but definitely was not the myth taught to us in elementary school, like Abe Lincoln carrying an ax, these are childish and frankly false ideas. Einstein stood on the shoulders of giants, and there was massive amounts of empirical evidence for Special Relativity going back thousands of years, really, billions.[1] [1] https://en.wikipedia.org/wiki/History_of_special_relativity https://en.wikipedia.org/wiki/History_of_special_relativity
  - macmuras 5y ago
    This has been on my mind for a while now. Heroes, such as Einstein, are good in that they motivate certain people, me included, to go into natural sciences, but once you start grasping more of historical context of scientific breakthroughs you begin to wonder why some scientists were elevated to that rank in general public's mind. I would say that this is some kind of PR type selection. It's natural that general public is aware of science communicators (amongs other things) like Carl Sagan, Jacob Bronowski or Neil deGrasse Tyson, but it is interesting that they wouldn't know as much about Lorenz, Poincare or Riemann, even though they have played significant roles in Special and General Relativity developments. There seems to be a preference for scientists that deal with more concrete problems, easier to understand in a very generic way (Cosmology seems to be a good pick). Also particular personal struggle like in Hawking's case or personality (Feynman comes to mind). So it is easier to talk about black holes and expanding universe (Hawking, Einstein) than abstract mathematics with none/loose/difficult to grasp connection to reality (Poincare, Riemann). Outside CS it might even be rare for people to know about Von Neumann. I wonder from current generation of scientists who will be remembered and what would be a reason behind it. There seems to be a requirement for some form of mystic atmosphere around a person in order to be talked about.
pdonis 5y ago
> Was the orbit of Mercury (or any other astronomical observations) important for the discover of Relativity. For general relativity, yes. > My understanding was that experimental impetus for relativity was the Michelson–Morley experiment This was one of the results that pointed the way to special relativity. It had nothing to do with general relativity. > General relativity was then developed on a purely theoretical basis. No, it wasn't. There was a huge body of experimental evidence already about gravity. It was true that all of that evidence, except for the anomalous precession of Mercury's perihelion, could be explained by Newtonian gravity; but general relativity, as a proposed new theory of gravity, had to also account for all of that experimental evidence. In other words, in the appropriate limiting case (weak fields and low speeds compared to the speed of light), general relativity had to reproduce all of the correct predictions of Newtonian gravity. That was a huge, and very important, experimental constraint. > Almost by definition, a theory that is ultimately useful can be confirmed without need of astronomy. Not if the differences between its predictions and the predictions of the previous theory (in this case Newtonian gravity) are only measurable in astronomical observations at the time the new theory is proposed. That was true of general relativity in 1915 and for at least a couple of decades afterwards. The differences between GR and Newtonian gravity for earthbound experiments were simply too small for the technology of the time to measure. So astronomical observations were the only way to test GR when it was proposed. > we could probably get GPS to work even without relativity Technology can of course be developed on a purely empirical basis, if you're prepared to make a lot of mistakes along the way that you wouldn't make without a good theoretical foundation. If it hadn't been for the knowledge of relativity on the part of the scientists involved, the GPS satellites probably would have been launched without any capability for adjusting their clock rates. Which would have meant that, once clock rate drift due to relativistic effects was seen, there would have been no way to adjust for it. So those satellites would have become expensive but useless toys, and a new constellation of satellites would have had to be built and launched.
- gizmo686 5y ago
  > No, it wasn't. There was a huge body of experimental evidence already about gravity. It was true that all of that evidence, except for the anomalous precession of Mercury's perihelion, could be explained by Newtonian gravity; but general relativity, as a proposed new theory of gravity, had to also account for all of that experimental evidence. In other words, in the appropriate limiting case (weak fields and low speeds compared to the speed of light), general relativity had to reproduce all of the correct predictions of Newtonian gravity. That was a huge, and very important, experimental constraint. Yes. I assumed that reproducing Newtonian gravity in the classical limit would be considered theoretical, as we had a solid theoretical understanding of Newtonian physics. Implicit in that would be a bunch of empirical evidence; but Einstein wouldn't need to explicitly think about the details of what evidence supported Newtonian mechanics (beyond the general understanding that it was all in the classical limit). > Not if the differences between its predictions and the predictions of the previous theory (in this case Newtonian gravity) are only measurable in astronomical observations at the time the new theory is proposed. Such a theory is not "useful", for many definitions of useful. Astronomical observations allowed us to verify Relativity earlier than we otherwise would be able to; but eventually technology advanced to the point where we could conduct satellite based experiments to directly confirm it. The theory was not practically useful until we had this technology. > Technology can of course be developed on a purely empirical basis, if you're prepared to make a lot of mistakes along the way that you wouldn't make without a good theoretical foundation. If it hadn't been for the knowledge of relativity on the part of the scientists involved, the GPS satellites probably would have been launched without any capability for adjusting their clock rates. Its not like we launched the entire GPS constellation then just hoped it would work. Before launching the GPS constellation, we launched the experimental Timation satellites to act as a proof of concept. Difficulties with maintaining accurate clocks in orbit would have been noticed then (if not sooner).
throwawaymaths 5y ago
> Having such evidence probably helped get the theory accepted faster I mean the original context is societal contribution, so getting something import understood faster I think counts, no?

onlyrealcuzzo 5y ago

Good luck finding a $1Tr project without real world evidence - just theoretical models.

flaburgan 5y ago
You mean like we do at CERN?
- jacquesm 5y ago
  You're off by a factor of 1,000.
  - throwawaylinux 5y ago
    How about the Iraq War?
    - Dylan16807 5y ago
      Is not a science project. If you're trying to make a weird point you need to be more direct, and if you're trying to make a political point you're just wasting everyone's time.
      - throwawaylinux 5y ago
        Original post didn't specify science project, just project.
        Dylan16807 5y ago
        Even ignoring context it's a huge stretch to call that a 'project'.
    - jacquesm 5y ago
      I fail to see the link between the budget of CERN and the cost of the Iraq war.
- deleted 5y ago
  [deleted]

fhars 5y ago

No, there was basically no empirical input into the development of special relativity either, Michelson-Morley was already perfectly explained by Lorentz contraction caused by movement of matter through the ether. What special relativity did was solve the purely theoretical contradictions between Newtonian mechanics and Maxwell's electrodynamics (hence the title of Einstein's paper "On the electrodynamics of moving bodies"), reinterpreting Lorentz' math for the description of movement through the ether as transformations of spacetime itself and doing away with the ether.

Maursault 5y ago
> No, there was basically no empirical input into the development of special relativity either There is a myth of Einstein that just isn't credible, which is that Einstein, while working as a patent clerk just came up with Special Relativity out of the blue without anyone's input, without the benefit of history. But Special Relativity was in the air. Henri Poincare was already writing about relativity, and so were others in years previous to Einstien's publication. If Einstein hadn't published when he did, someone else would have within a few years at best. Einstein was amazing, also, just a man, but definitely was not the myth taught to us in elementary school, like Abe Lincoln carrying an ax, these are childish and frankly false ideas. Einstein stood on the shoulders of giants, and there was massive amounts of empirical evidence for Special Relativity going back thousands of years, really, billions.[1] [1] https://en.wikipedia.org/wiki/History_of_special_relativity https://en.wikipedia.org/wiki/History_of_special_relativity
- macmuras 5y ago
  This has been on my mind for a while now. Heroes, such as Einstein, are good in that they motivate certain people, me included, to go into natural sciences, but once you start grasping more of historical context of scientific breakthroughs you begin to wonder why some scientists were elevated to that rank in general public's mind. I would say that this is some kind of PR type selection. It's natural that general public is aware of science communicators (amongs other things) like Carl Sagan, Jacob Bronowski or Neil deGrasse Tyson, but it is interesting that they wouldn't know as much about Lorenz, Poincare or Riemann, even though they have played significant roles in Special and General Relativity developments. There seems to be a preference for scientists that deal with more concrete problems, easier to understand in a very generic way (Cosmology seems to be a good pick). Also particular personal struggle like in Hawking's case or personality (Feynman comes to mind). So it is easier to talk about black holes and expanding universe (Hawking, Einstein) than abstract mathematics with none/loose/difficult to grasp connection to reality (Poincare, Riemann). Outside CS it might even be rare for people to know about Von Neumann. I wonder from current generation of scientists who will be remembered and what would be a reason behind it. There seems to be a requirement for some form of mystic atmosphere around a person in order to be talked about.

pdonis 5y ago

> Was the orbit of Mercury (or any other astronomical observations) important for the discover of Relativity. For general relativity, yes. > My understanding was that experimental impetus for relativity was the Michelson–Morley experiment This was one of the results that pointed the way to special relativity. It had nothing to do with general relativity. > General relativity was then developed on a purely theoretical basis. No, it wasn't. There was a huge body of experimental evidence already about gravity. It was true that all of that evidence, except for the anomalous precession of Mercury's perihelion, could be explained by Newtonian gravity; but general relativity, as a proposed new theory of gravity, had to also account for all of that experimental evidence. In other words, in the appropriate limiting case (weak fields and low speeds compared to the speed of light), general relativity had to reproduce all of the correct predictions of Newtonian gravity. That was a huge, and very important, experimental constraint. > Almost by definition, a theory that is ultimately useful can be confirmed without need of astronomy. Not if the differences between its predictions and the predictions of the previous theory (in this case Newtonian gravity) are only measurable in astronomical observations at the time the new theory is proposed. That was true of general relativity in 1915 and for at least a couple of decades afterwards. The differences between GR and Newtonian gravity for earthbound experiments were simply too small for the technology of the time to measure. So astronomical observations were the only way to test GR when it was proposed. > we could probably get GPS to work even without relativity Technology can of course be developed on a purely empirical basis, if you're prepared to make a lot of mistakes along the way that you wouldn't make without a good theoretical foundation. If it hadn't been for the knowledge of relativity on the part of the scientists involved, the GPS satellites probably would have been launched without any capability for adjusting their clock rates. Which would have meant that, once clock rate drift due to relativistic effects was seen, there would have been no way to adjust for it. So those satellites would have become expensive but useless toys, and a new constellation of satellites would have had to be built and launched.

gizmo686 5y ago
> No, it wasn't. There was a huge body of experimental evidence already about gravity. It was true that all of that evidence, except for the anomalous precession of Mercury's perihelion, could be explained by Newtonian gravity; but general relativity, as a proposed new theory of gravity, had to also account for all of that experimental evidence. In other words, in the appropriate limiting case (weak fields and low speeds compared to the speed of light), general relativity had to reproduce all of the correct predictions of Newtonian gravity. That was a huge, and very important, experimental constraint. Yes. I assumed that reproducing Newtonian gravity in the classical limit would be considered theoretical, as we had a solid theoretical understanding of Newtonian physics. Implicit in that would be a bunch of empirical evidence; but Einstein wouldn't need to explicitly think about the details of what evidence supported Newtonian mechanics (beyond the general understanding that it was all in the classical limit). > Not if the differences between its predictions and the predictions of the previous theory (in this case Newtonian gravity) are only measurable in astronomical observations at the time the new theory is proposed. Such a theory is not "useful", for many definitions of useful. Astronomical observations allowed us to verify Relativity earlier than we otherwise would be able to; but eventually technology advanced to the point where we could conduct satellite based experiments to directly confirm it. The theory was not practically useful until we had this technology. > Technology can of course be developed on a purely empirical basis, if you're prepared to make a lot of mistakes along the way that you wouldn't make without a good theoretical foundation. If it hadn't been for the knowledge of relativity on the part of the scientists involved, the GPS satellites probably would have been launched without any capability for adjusting their clock rates. Its not like we launched the entire GPS constellation then just hoped it would work. Before launching the GPS constellation, we launched the experimental Timation satellites to act as a proof of concept. Difficulties with maintaining accurate clocks in orbit would have been noticed then (if not sooner).

throwawaymaths 5y ago

> Having such evidence probably helped get the theory accepted faster I mean the original context is societal contribution, so getting something import understood faster I think counts, no?