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There is something else you should also consider here. As theoretical physics and experimental physics have started to grow further and further apart, there are

There is something else you should also consider here. As theoretical physics and experimental physics have started to grow further and further apart, there are people who have devoted their entire careers, in many cases their entire lives, to purely theoretical pursuits which may in the end simply be invalid. But at some point you reach a point of no return in your career - in that you would need to effectively reboot your entire life, which may be quite decorated by this point, in some entirely new direction leaving you going from leading expert to mid (or older) aged neophyte. There is a reason Max Planck famously said, "Science advances one funeral at a time." And that was back when experimental and theoretical were still very closely intertwined! One problem with dark matter is that there have been an increasingly large number of quite clever experiments to try to detect various concepts of it, WIMPs in particular. And each and every one has been a negative. This should, in and of itself, begin to cast down on the hypothesis even lacking a better alternative.

cygx 8y ago
This should, in and of itself, begin to cast down on the hypothesis even lacking a better alternative. Only if your search was exhaustive: Scooping up a spoonful of ocean is not enough to conclude fish do not exist...
- TangoTrotFox 8y ago
  That's really the problem here though. You cannot falsify dark matter, and you cannot prove a negative. Imagine I say there is a 5 headed green deer that weighs 2000 pounds and can speak Gaelic, but it's really good at avoiding being spotted - so good in fact that you can even look at right at it and might not see it. And you can even touch it and not even know you're touching it! What would you could consider an exhaustive proof of its lack of existence? You can leave carrots everywhere, but perhaps it doesn't like carrots. Or maybe you didn't spot it eating those carrots. Maybe you left them in the wrong spot, or at the wrong time. Maybe you need bigger carrots. Maybe you need smaller carrots. Maybe it likes cooked carrots instead of raw carrots. Maybe you need a better camera. Maybe the reason you camera didn't catch it is because you weren't using a flash, or maybe you need to setup an infrared camera, maybe you need to play a Gaelic greeting on loop, etc, etc. You can compile a literally infinite number of ideas to try to detect our dear deer. Instead with non falsifiable theories, all you can do is approach them from an abundance of failures. You've tried carrots, you've tried infrared, you've tried ..., and it's still not coming out. Each failure makes it more and more likely that our deer simply does not exist. Of course this does not mean it definitively does not, but nothing will ever mean that.
  - cygx 8y ago
    The idea of non-visible matter as a fix for stellar motion dates back to the 19th century, when our knowledge about the cosmos was far more limited (remember, we only learned about other galaxies in the 1920s - it post-dates general relativity!). That the hypothesis is still viable today with our more elaborate understanding of the universe does validate the idea to some degree: Our cosmological models cut have killed it off easily. So unless a better model that works equally well comes along, I see no reason to discard the dark matter hypothesis just yet: The universe has no obligation to be filled with a type of matter detectable with the means of today...
    - marcosdumay 8y ago
      Yes, it dates to the XIX Century, and alternative types of it have been proven right or wrong at times. Postulating unobservable things is still not a good way to do science. The one good thing of the dark matters theories was that physicists were clear in that it's not a done model, just a map of what's wrong with our understanding. This seems to have changed lately.
    - TangoTrotFox 8y ago
      I'd generally agree with you, except for one thing. I'm not sure our models could have killed it off, excepting finding precisely whatever is causing the apparent mass abnormalities throughout the universe. Have you seen those ancient astronomic models used to illustrate a geocentric Earth? The one with the numerous spinning 'petals' surrounding the Earth? It's interesting imagining the amount of work that went into creating such models, constantly adjusting them over and over each time yet another little problem came up. Happily accepting planets just randomly changing direction, with no analog whatsoever anywhere else in nature, and so on. When hypotheses are not falsifiable, they just tend to grow ever more elaborate rather than die. Dark matter started off as literally that - a place holder for bodies that did not significantly radiate. It's slowly changed into becoming the vast majority of all matter in the universe, existing practically everywhere, it can't be baryonic, it interacts with nothing except itself and gravity, there must exist near entirely dark matter galaxies, and so forth. So we're left with this ever evolving hypothesis that can't ever really be falsified and which every test, increasingly clever and precise, we create to detect it -- says it's not there. And it seems that the zeitgeist is starting to increasingly treat dark matter as a fact whose proof is little more than an unscheduled formality. This seems illogical given that we've done more than ever to try to show it exists, and every result is saying - nope. And again this does not mean it does not exist, but each failure makes it more likely that this is the case, and there is an alternative explanation.

cygx 8y ago

This should, in and of itself, begin to cast down on the hypothesis even lacking a better alternative. Only if your search was exhaustive: Scooping up a spoonful of ocean is not enough to conclude fish do not exist...

TangoTrotFox 8y ago
That's really the problem here though. You cannot falsify dark matter, and you cannot prove a negative. Imagine I say there is a 5 headed green deer that weighs 2000 pounds and can speak Gaelic, but it's really good at avoiding being spotted - so good in fact that you can even look at right at it and might not see it. And you can even touch it and not even know you're touching it! What would you could consider an exhaustive proof of its lack of existence? You can leave carrots everywhere, but perhaps it doesn't like carrots. Or maybe you didn't spot it eating those carrots. Maybe you left them in the wrong spot, or at the wrong time. Maybe you need bigger carrots. Maybe you need smaller carrots. Maybe it likes cooked carrots instead of raw carrots. Maybe you need a better camera. Maybe the reason you camera didn't catch it is because you weren't using a flash, or maybe you need to setup an infrared camera, maybe you need to play a Gaelic greeting on loop, etc, etc. You can compile a literally infinite number of ideas to try to detect our dear deer. Instead with non falsifiable theories, all you can do is approach them from an abundance of failures. You've tried carrots, you've tried infrared, you've tried ..., and it's still not coming out. Each failure makes it more and more likely that our deer simply does not exist. Of course this does not mean it definitively does not, but nothing will ever mean that.
- cygx 8y ago
  The idea of non-visible matter as a fix for stellar motion dates back to the 19th century, when our knowledge about the cosmos was far more limited (remember, we only learned about other galaxies in the 1920s - it post-dates general relativity!). That the hypothesis is still viable today with our more elaborate understanding of the universe does validate the idea to some degree: Our cosmological models cut have killed it off easily. So unless a better model that works equally well comes along, I see no reason to discard the dark matter hypothesis just yet: The universe has no obligation to be filled with a type of matter detectable with the means of today...
  - marcosdumay 8y ago
    Yes, it dates to the XIX Century, and alternative types of it have been proven right or wrong at times. Postulating unobservable things is still not a good way to do science. The one good thing of the dark matters theories was that physicists were clear in that it's not a done model, just a map of what's wrong with our understanding. This seems to have changed lately.
  - TangoTrotFox 8y ago
    I'd generally agree with you, except for one thing. I'm not sure our models could have killed it off, excepting finding precisely whatever is causing the apparent mass abnormalities throughout the universe. Have you seen those ancient astronomic models used to illustrate a geocentric Earth? The one with the numerous spinning 'petals' surrounding the Earth? It's interesting imagining the amount of work that went into creating such models, constantly adjusting them over and over each time yet another little problem came up. Happily accepting planets just randomly changing direction, with no analog whatsoever anywhere else in nature, and so on. When hypotheses are not falsifiable, they just tend to grow ever more elaborate rather than die. Dark matter started off as literally that - a place holder for bodies that did not significantly radiate. It's slowly changed into becoming the vast majority of all matter in the universe, existing practically everywhere, it can't be baryonic, it interacts with nothing except itself and gravity, there must exist near entirely dark matter galaxies, and so forth. So we're left with this ever evolving hypothesis that can't ever really be falsified and which every test, increasingly clever and precise, we create to detect it -- says it's not there. And it seems that the zeitgeist is starting to increasingly treat dark matter as a fact whose proof is little more than an unscheduled formality. This seems illogical given that we've done more than ever to try to show it exists, and every result is saying - nope. And again this does not mean it does not exist, but each failure makes it more likely that this is the case, and there is an alternative explanation.