Things go in cycles, they say. Maybe more in history than in physics. In 600 BC Thales started an era of scientific thought by rejecting the idea that nature is driven by the Greek Gods and argued that it was made of water. This idea was more incisive than it seems at first sight, because unlike every theory that preceded it, it was testable. This great tradition of Greek science continued for seven centuries and included such greats as Aristarchus who suggested the Sun-centred Solar system and Hero with his steam engine (AD 100).
The death blow for Greek astronomy occurred seven centuries after Thales, when Ptolemy in 150 AD used the new tool of geometry, to make a complex Earth-centred model using many oscillating circles (epicycles) which worked well enough to fit planetary motion, for the wrong reasons, as it is easy for complex systems to do. After Ptolemy 1200 years of intellectual darkness descended (despite a few brief flashes in the dark). Of course, it was not all poor Ptolemy's fault since the zeitgeist was moving away from science as well, he was more like a symptom than a cause, but the effect of the epicycles on human thought was dulling.
Scientific enquiry started again 1200 years later around 1300 AD when William of Occam realised that complex models are false friends, and can easily be right for the wrong reason, and proposed Occam's razor (keep it simple). 'Roger' Bacon (thanks qraal) then supported the importance of experimental evidence. Humankind was finally self-correcting and after people like Kepler, Galileo and Newton applied logic (maths) to this reawakened scientific mindset a revolution soon followed.
Now seven hundred years after Occam and Bacon, physics is in danger once more. This time from dark matter, which is just as insidious as Ptolemy's epicycles: a complex fudge to allow an old theory to fit new data. Physicists have used data from galaxy rotation and the new tool of computers to work out what ad hoc complex distributions of invisible stuff will allow the old theories to fit the newly-observed galactic rotation and in so doing have backed themselves into a dark corner it'll be hard to get out of. Specifically, it is unsatisfactory because:
1. Dark matter is ad hoc. It is added to the cosmos by definition to make general relativity predict the data, so, like the epicycles, it inverts the scientific method of changing theories to suit facts, and changes uncheckable 'facts' to suit the theory.
2. It is complex. Rather like the epicycles, it has so many versions and so much flexibility that it is possible for it to appear to work, and yet be absolute rubbish.
3. Mainstream astrophysics must now claim that 95% of the cosmos is made of dark stuff and their model therefore predicts only 5% of the cosmos. If the Met Office only had a 5% success rate I think they'd be revising their model.
4. Dark matter is often presented in the articles I read as doubtless fact, always a danger sign.
5. Popper: any theory that is not falsifiable is not scientific. Dark matter is not falsifable. If they don't find any tomorrow they'll ask for funding to look in a different regime, as has happened many times.
My point is that if dark matter is allowed to absorb almost all the physics funding, then it will stop progress in the same way that Ptolemy's epicycles killed Greek astronomy. It is right on cue as well, roughly seven centuries after Roger Bacon and William of Occam restarted the scientific process. We need to look back at the mindset they had: take no-one's word for it, keep it as simple as possible, look at the data without prejudice, disregard received opinion. The opposite to today's mainstream.
Observations used by Galileo to prove the Sun-centred theory which could have saved Aristarchus' model much earlier, are the phases of Venus. In Ptolemy's Earth-centred Solar system model, Venus could never be behind the Sun, so could never be fully illuminated (see the first reference below). It should have always shown a crescent. In reality, Venus shows phases, sometimes full, sometimes crescent, supporting a Sun-centred model. These phases are just about visible to the naked eye and had been noticed, it is thought, by the Babylonians (Venus has horns they said). Aristotle was sensibly susceptible to data: he had decided the Earth was round by looking at the curved shadow of the Earth during a lunar eclipse. Just imagine if he'd studied the phases of Venus? Being swayed by observation he may well have opted for a heliocentric theory and erased 1200 years of human stagnation. We might be settling Tau Ceti now..
More to the point, what observations in our time unambiguously discredit dark matter? The problem is that dark matter's adjustability (like the epicycles) means it is not easily falsifiable, but there are some data that embarrass it, eg: the anomalous spin of globular clusters which are too small to have dark matter, the alignment of quasars, the critical acceleration in galaxies, the overall agreement of lots of anomalies with MiHsC. Acceptance of these observations at this point may well save us from a 1200 year dark age.
Send any further such observations to the Seldon project, planet Terminus, or, failing that, post a comment below :)
More to the point, what observations in our time unambiguously discredit dark matter? The problem is that dark matter's adjustability (like the epicycles) means it is not easily falsifiable, but there are some data that embarrass it, eg: the anomalous spin of globular clusters which are too small to have dark matter, the alignment of quasars, the critical acceleration in galaxies, the overall agreement of lots of anomalies with MiHsC. Acceptance of these observations at this point may well save us from a 1200 year dark age.
Send any further such observations to the Seldon project, planet Terminus, or, failing that, post a comment below :)
References
Venus reference: http://astronomy.nmsu.edu/geas/lectures/lecture11/slide02.html
Asimov, I., 1951. Foundation. Gnome Press.
15 comments:
You mean like string theory that has sucked up a lion's share of the funding?
Big Bang cosmology looks like a collaboration between Rube Goldberg and M.C. Escher.
You mean like string theory that has sucked up a lion's share of the funding?
Big Bang cosmology looks like a collaboration between Rube Goldberg and M.C. Escher.
Indeed: string theory is just as bad as dark matter: complex and not falsifiable, and the evidence for the big bang is indirect so I don't trust that either.
Rube Goldberg is a good analogy for all these convoluted theories (in the UK we had Heath Robinson). The difference is those guys did it for entertainment..
I once attended a talk by a string theorist and wrote a blog entry about that, here:
http://physicsfromtheedge.blogspot.co.uk/2012/05/in-between-models.html
Mike,
Good post. I remember reading a statement, maybe 30 or 40 years ago, that Einstein/Lobachevsky space was Euclidean in 11 dimensions. Being kind of a one dimensional guy at the time I was more interested in pursuing girls as opposed to theories, thus didn't follow up.
At base, most all dynamic physical theories are geometric mappings expressed as a set of simultaneous partial differential equations. The squirrels in the attic are all those arbitrary constants of integration. Unconstrained by experimental evidence it is "dial a universe" time. It can lead to wondrous things - black holes, neutronium, dark matter, unicorns... Refined Onanism.
Regards,
Roy
I did wonder if apparent dark matter was a side effect of living in a Multiverse, and the effects we see are simply gravity tunneling across that barrier.
Also various people have suggested that EmDrive might in fact be taking energy from parallel space-times and thus balancing out the system.
Perhaps in another Universe the equivalent device is increasing local inertia and not decreasing it, due to a reversed arrow of time or similar.
I just now came up with a saying:
Astrophysics has gone dark, because there aren't enough bright minds left to illuminate the universe.
Dear ZeroIsEverything: Poetic :) I'd say that minds may still be bright, but instead of being like light bulbs illuminating a lot of space or at least like a bunch of torches following their own curiosity and pointing in many directions, the majority are now more like torches all pointing the way authority tells them, ie: the same way. You get a larger area of dark that way. In my opinion the problem is not lack of brightness, but lack of independence.
Hi Mike
One fact check: in the 13th Century it was Roger Bacon, not his 17th Century intellectual kinsman Francis. James Blish's amazing novel, "Doctor Mirabilis", is a good introduction to his world. Francis Bacon was more theorist than experimentalist and died from pneumonia he caught after trying to stuff a chicken with snow in a food preservation experiment.
qraal: thanks for that. I often get them mixed up. Now corrected..
While paddleboarding some near and shallow Internet for related stuff, I just found out, that lack of evidence for dark matter is rather mainstream these days (of course, if we don't count mainstream media "science" articles, which present dark matter as "fact", as was criticized )
http://phys.org/news/2012-04-dark-theories-mysterious-lack-sun.html
(I really lack discussions on this topic more recent than 2012, to be true)
Anyway, I would prefer to treat following topics more or less separately:
- Pointing out, that dark matter is rather suspicious, non-scientific theory, with lack of evidence, contradictory evidence (see above), etc. ... mainstream acceptance can be explained by simplicity (much more simple to grasp then relativity, which is counter-intuitive - on the other hand, people are used to believe in something invisible, either not-yet-observed, or perhaps not observable at all - like ghosts, etc., it is probably closely related to animism). This can be done by discussing history of science, which I like to do myself.
- It must be understood, that anomalies (especially observational, like galaxy rotation, not experimental, which may be hard to reproduce) are not "you just haven't observed/measured it hard enough" phenomenons: it is not that we have to tweak our observations until they fit some nice theory which we should believe, we live in "what you see is what you get" universe... of course, sometimes there are artifacts of the way observation is done (like FTL neutrinos), but sometimes not, and lot of anomalies are not frauds or mistakes, but real data outside existing models. This can be done by talking more about anomalies, and verifying them, instead of hiding them.
- MiHsC basic "magic formula", compared to other alternatives to dark matter (like MOND). This is harder to do, because something about it at least as counter-intuitive, as relativity was, or as quantum mechanics is. If MiHsC is right, it needs its Michelson-Morley experiment, which may (or may not) be Emdrive (the trouble is, that Michelson-Morley experiment was expected to show something, but it never did, consistently, while EmDrive seems to sometimes work and sometimes not and it is hard to predict why or to reproduce)
- EmDrive may work (and also may be experimental error, of course also of some novel type), but still may be completely unrelated to MiHsC and horizons (which still may be the right explanation of anomalies on cosmological scale). I just want to say that MiHsC may be really THE galaxy rotation theory of choice... but there may be anomalous phenomena, which are just not related to it: it is not last theory, of "theory of all", it is just one of many mechanisms, on of models. There may be interesting anomalies, which are simply caused by something else.
- Computer simulations will have to be done, one day (like for other theories). As long as math is involved, we can try to see what happens, when computer crunches data (the simulation may also be nonlinear, but still we can see what happens when there are lot of objects with different accelerations and don't oversimplify... maybe new interesting coincidences will surface... any, theories challanging Dark Matter would need to account for https://en.wikipedia.org/wiki/Structure_formation )
'Aero' at NSF invoked your EM Drive formula while playing with his accumulated databases. The results are...worth taking a look at.
One funny things I have just realized: there is actually one planet (well, dwarf, but still planet :-)), which actually moves in an orbit similar to some kind of Ptolemaian epicycle: and it is Pluto (but of course, it is not epicycle synced with annual orbit of Earth around Sun... eh, pardon with annual plane change of orbit of Sun around Earth :-) ... but rather synced with orbit of its moon Charon)
Michael: Yes, finally after 400 yrs of shame Ptolemy has a tiny giggle, but only a superficial one :)
Tim: Interesting work by aero: a fractal emdrive (made up of smaller emdrives) produces more force, but this assumes the power input (P) is the same for all, so replacing 1 emdrive with 14 smaller ones, would require 14P, which makes sense.
This reminds me of the opening of Scott Tyson's book, The Unobservable Universe. His theory also eliminates dark matter and dark energy, and includes the gravity of space beyond the time-reach of light as the real reason for redshifting.
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