Looking For a Theory whose entities turned out not to exist

  1. Hey. I'm currently studying philosophy of physics and was looking around to find something I need. Basically I'm looking through the history of science to find cases where a theory posited entities that were supposed to have existed but failed. In other words, the theory had some true predictions, was somewhat verified and was then rejected because the entities it posited didn't exist.

    The main one I'm looking at is the 19th century aether theory. EM radiations are waves. Back then, scientists assumed that since EM radiation is waves then there must be a medium. It was pretty much unfathomable to have waves independent of a medium (I know that currently some scientists posit the space-time continuum as the 'aether', but that's irrelevant for me). Aether was discredited by the Michelson and Morely experiment. My only problem with this is that even though aether was considered somewhat of a necessity back then, I couldn't find any scientist of that time writing about the topic (probably because it was very short lived).

    Are there any such theories in physics or chemistry where an entity was indispensable to the theory and then the entity turned out to be false even though the theory has some true predictions?

  2. jcsd
  3. AlephZero

    AlephZero 7,298
    Science Advisor
    Homework Helper

    If you want to go a bit further back in time: phlogiston.
    collinsmark likes this.
  4. SteamKing

    SteamKing 8,304
    Staff Emeritus
    Science Advisor
    Homework Helper

    Even further back: Ptolemy and his epicycles.
  5. Thanks. The newer better (Due to the advancement in scientific methodology) but the phlogiston seems to work. Thanks a lot.

    If there are any newer ones, please let me know.
  6. Nugatory

    Staff: Mentor

    In biology, life-force theories were circulating well into the 20th century.
    Indeed, they're still animating a fair amount of online crackpottism and quackery today (which may make them hard to research - there's a loy of garbage to plow through).
  7. Bobbywhy

    Bobbywhy 1,908
    Gold Member

    The "Steady State Theory" and the "Quasi-Steady State Theory" could be examples. Certainly those proposing those theories suggested experiments to prove their theories correct, but, alas, it never happened!
    Last edited: Aug 27, 2013
  8. Doesn't really work because I'm looking for theories, advocated by proper scientists with experimental verification, though later they were falsified because the entities they posit didn't exist. My point in looking at this is to show that scientists test the entities of a theory independently of the theory. A theory could be corroborated over and over, hell, there could great reasons for believing such entities (such as aether). But when attempting to 'observe' (I'm using that term loosely) those entities, we cannot find them.
  9. Nugatory

    Staff: Mentor

    That's going to be a lot harder to find. Of the examples already cited in this thread, aether, phlogiston, and life-force were all conjectured/assumed to exist (with good reason! Even before the notion of "proper scientist" emerged sometime in the 19th century, the players were smart people not given to sloppy thinking or overlooking the obvious) but then didn't make it past the "experimental verification" hurdle.

    Of the things already cited in this thread, you could make a case that Ptolemaic epicycles were empirically confirmed but then abandoned.

    But mostly you're going to find that once something is experimentally confirmed it stays that way. For example, we know that, despite all its experimental successes on the surface of the earth, in the motion of the planets, in navigating spacecraft and aiming artillery, Newtonian gravity is "wrong" compared to the predictions of general relativity. But that hardly makes Newton wrong or invalidates the centuries of success that we've had with Newtonian gravity.
  10. The case of phlogiston and caloric theory of heat were actually experimentally confirmed for a while. Caloric theory of heat was in fact experimentally successful until Rumford.

    True, but a case can be made (on a purely theoretical level) that there are extremely small (in fact negligible) corrections to Newtonian mechanics.

    But I don't disagree with you. Once an experiment is preformed the results remain. But my point is exactly this, experimental phenomena always are the same, it's the theories that keep getting altered. What we experimentally 'observe' is true. But we can never say that with absolute certainty about our theories.

    I just wanted to make the case stronger by finding a theory that was considered very successful until it was abandoned due to an experiment later on that showed the entity not to exist (the caloric, in this case).
  11. arildno

    arildno 12,015
    Science Advisor
    Homework Helper
    Gold Member

    Remember that theory production always implies a generalization from which deductions can be made that as yet has no empirical verification.

    Thus, the possibility exists, within any theory, that those deductions will be proven false, i.e, that the specific generalization made by the theory must be rejected.
  12. SteamKing

    SteamKing 8,304
    Staff Emeritus
    Science Advisor
    Homework Helper

    There's this little chestnut from more recent times: N-rays


    In all the hoopla surrounding the discovery of X-rays, everyone and their mother was jumping into radiation physics to see who could discover the next big thing in the field. Although some scientists reported the confirmation of N-rays, eventually the whole episode collapsed when a clever observer secretly switched out key parts of the device used to observe the N-rays, and yet the experimenters still reported the presence of these non-extant rays.
  13. Thanks for the replies. But I think I'm going to use the perturbations in Mercury and Uranus' orbit. Whereas one proved the existence of another planet, another failed to do so even though the predictions for both were pretty similar.
  14. Nugatory

    Staff: Mentor

    Hey - good one! thanks, I had completely forgotten that cautionary little tale.
  15. Pythagorean

    Pythagorean 4,577
    Gold Member

    not sure if the ether counts as an entity, but an experiment disproved it :)
  16. Thanks, but I already mentioned it in my first post. Do you know of any scientists, philosophers writing about it in that time? The only thing I see is the experiments that disproved it. But then again, its appeared and vanished too quickly for any substantial discourse on the topic.
  17. Pythagorean

    Pythagorean 4,577
    Gold Member

    Ah, I responded on the title, my apologies.

    Huygens was talking about the ether as far back as 17th century.
  18. kith

    kith 839
    Science Advisor

    The ether was discussed for a long time. Newton and Maxwell for example wrote about it. Even after the Michelson-Morley experiment, Lorentz developed a sophisticated ether theory which is said to be equivalent to SRT (but of course less elegant).

  19. Evo

    Staff: Mentor

    I think you need to step back and decide whether you want what was considered valid science, or what was/is considered philosophy. Since we are a science forum, let's stick to actual science please.
    Last edited: Aug 29, 2013
  20. I am actually talking about science and scientists who wrote about it. Sorry if I implied otherwise. I'm just looking for something specific that scientists actually said about an entity.

    Anyways 18th-19th century atomic chemistry turned out to work quite so well. So thanks.
Know someone interested in this topic? Share a link to this question via email, Google+, Twitter, or Facebook