“isn’t it quite odd that looking around at different parts of the universe seems to produce such a striking level of agreement on how much missing mass there is?”
But they don’t. Dark matter, as a theory, posits that the amount of mass that “must be there somewhere” varies in amount and distribution in an ad-hoc fashion to explain the observations. I think it’s likely that whatever is wrong with the theory, on the other hand, isn’t varying wildly by where in the universe it is. Any such explanation would (need to) be more parsimonious, not less so.
And I agree that physics isn’t obligated to make things easy to find—but when the dark matter theory was postulated, they guessed it was a certain type of WIMP, and then kept not finding it. Postulating that it must be there somewhere, and physics doesn’t need to make it easy, isn’t properly updating against the theory as each successive most likely but still falsifiable guess has been falsified.
Postulating that it must be there somewhere, and physics doesn’t need to make it easy, isn’t properly updating against the theory as each successive most likely but still falsifiable guess has been falsified.
Most physicists actually have updated—if you listen to Sean Carroll’s podcast, he just this week talked about how when the LHC started up he thought there was about a 60% chance of finding a dark matter candidate, and that he’s updated his views in light of our failure to find it. But he also explained that he still thinks dark matter is overwhelmingly likely (because of evidence like that explained in the post).
That’s good to hear. But if “he started at 60%,” that seems to mean if he “still thinks dark matter is overwhelmingly likely” he is updating in the wrong direction. (Perhaps he thought it was 60% likely that the LHC found dark matter? In which case I still think that he should update away from “overwhelmingly likely”—it’s weak evidence against the hypothesis, but unless he started out almost certain, “overwhelmingly” seems to go a bit too far.)
Yes, 60% that the LHC would find a dark matter candidate. Anyhow, maybe you should take away that this emphasizes that he does (and cosmologists in general do) have lots of evidence.
“isn’t it quite odd that looking around at different parts of the universe seems to produce such a striking level of agreement on how much missing mass there is?”
But they don’t. Dark matter, as a theory, posits that the amount of mass that “must be there somewhere” varies in amount and distribution in an ad-hoc fashion to explain the observations. I think it’s likely that whatever is wrong with the theory, on the other hand, isn’t varying wildly by where in the universe it is. Any such explanation would (need to) be more parsimonious, not less so.
And I agree that physics isn’t obligated to make things easy to find—but when the dark matter theory was postulated, they guessed it was a certain type of WIMP, and then kept not finding it. Postulating that it must be there somewhere, and physics doesn’t need to make it easy, isn’t properly updating against the theory as each successive most likely but still falsifiable guess has been falsified.
Most physicists actually have updated—if you listen to Sean Carroll’s podcast, he just this week talked about how when the LHC started up he thought there was about a 60% chance of finding a dark matter candidate, and that he’s updated his views in light of our failure to find it. But he also explained that he still thinks dark matter is overwhelmingly likely (because of evidence like that explained in the post).
That’s good to hear. But if “he started at 60%,” that seems to mean if he “still thinks dark matter is overwhelmingly likely” he is updating in the wrong direction. (Perhaps he thought it was 60% likely that the LHC found dark matter? In which case I still think that he should update away from “overwhelmingly likely”—it’s weak evidence against the hypothesis, but unless he started out almost certain, “overwhelmingly” seems to go a bit too far.)
Yes, 60% that the LHC would find a dark matter candidate. Anyhow, maybe you should take away that this emphasizes that he does (and cosmologists in general do) have lots of evidence.