And now...

... for something completely different.

Modern-day mainstream cosmology (that branch of physics trying to understand why our universe is the way it is) holds that 80% of the total mass present in the universe is so-called 'dark matter'. It is a mysterious substance, that neither emits nor scatters light. The only way it is observable is through the gravitational effects this mysterious matter has on the universe around us.

And it is completely theoretical.

Dark matter was proposed as a solution to make the Einstein models of the universe fit the observations we have on the real one. Introducing dark matter into the models has been very successful in explaining a number of phenomena we observe in our universe: Gravitational lensing (a distortion of our view of the universe by gravity acting on light as it crosses space from its source to our receivers), the non-uniform distribution of the radiation left over from the Big Bang (the so-called background radiation) and the strange way in which spiral galaxies rotate.

But there are studies that shine a worrying light on the actual existence of dark matter. For instance, dark matter and black holes do not interact. And that is a bit weird, if you consider that the defining characteristic of both is gravity. This seems to create a bit of paradox.

This seeming paradox hinges on the assumption in main-stream cosmology that clusters of galaxies are evenly distributed throughout the universe. That means that objects like galaxies are affected equally on all sides by gravitational pull of far-away matter. In other words: Gravitational effects form far away matter cancel each other out. However, this may not be the case. In fact, it has been suggested that the way galaxies and clusters of galaxies are organized around the universe is fractal, not uniform.

Running with the idea of a fractal universe, mathematician Andrea Carati modelled the way spiral galaxies rotate. In his study he assumes a non-uniform, fractal distribution of galaxies. This results in non-uniform gravitational effects. In fact, on large scale objects (galaxies and larger) he finds that far-away clusters of galaxies exert a significant 'tidal' effect. With a little more math, Carati came up with predictions of how a spiral galaxy would rotate under such conditions. His results (pdf) were spectacular. Applying his mathematical model to a number of observed galaxies, his predictions are virtually identical to the observed rotation speeds. And he doesn't have to resort to dark matter to get this good a fit.

My inner geek finds this incredibly cool. To me the idea of dark matter and dark energy always seemed to be the equivalent of the 'aether', which 19th century physics needed to explain the propagation of electro-magnetic (light and radio) waves. It is ugly and rather brutal. And it rests solely on the assumptions underpinning our 'best' models of the universe. Dark matter just HAS TO exist, because the models are wrong without it (are those echoes of the AGW CO2 hypothesis I hear?).

But here we have in Carati a potential scientific hero, replacing a key assumption about our universe with an alternative. And is able to explain observations just as well without dark matter. One of the three main phenomena that 'prove' the existence of dark matter, can be adequately explained without filling our universe with an invisible goo to the tune of 4 times the mass of the observable universe. It is beautifully elegant. Stuff like this just brighten my day.

(via Vox Day; Normal programming will resume shortly)

10 opmerkingen:

Alfred the Ordinary zei

Let's not forget that the introduction of the universal constant was also a fudge when it was noticed that e=mc2 was flawed. Instead of acknowledging the error and looking for the reason, a fudge was required to stick to the model.

Jeremy Johnson zei

"We're dealing the medievalism here." - Dr. McCoy, Star Trek 4

By the end of this century, we will be pretty much were we were at the end of the 20th Century; will have replaced a lot of embarrassingly bad scientific theories from 100 years ago with ones that are slightly better but still probably wrong.

I've been into astronomy and the physics thereof since I was a kid; there's a lot of really interesting stuff going on right now, and a lot of really dumb stuff. Unsurprisingly the stupid stuff is politically motivated.

Just as long as we get enough right to find a reasonable (non-fatal) means for me to get off this rock and somewhere else, I will be a happy camper.

Fredy zei

Something that’s too often forgotten nowadays is that
science is always wrong and that we always need to adjust our views to make it

My Sunday highlight was looking at this inspiring graph:

Republicans apparently want change, real change, change they
can believe in. They even forgive the leading candidate his past sins, as long
as they don’t get that middle of the road humbug that’s so close to Obama. Extra
bonus is that this will upset the whole European establishment and will give
wings and will bring Wilders into the mainstream in Western politics. I just can’t
wait to see the liberal and European media get nuts about this guy!

Check out his stand on Islam:

Klein Verzet zei

I think your mixing things up a bit. The famous E = M c^2 equation is from 'special relativity' dealing with light. The cosmological constant, the fudge factor, was dreamt up by Einstein to produce a steady-state universe using his 'general relativity' mathematics.

But that is a good example of the same phenomenon: Einstein (and his contemporaries) just 'knew' that the universe was eternal and unmoving. And thus he introduced his 'cosmological constant' to produce a model universe in line with what everyone insisted the real universe was like. It was only later that others (like Hubble) made observations that suggested an expanding universe.

To his credit, Einstein later acknowledged that his constant was 'his biggest blunder'. But it goes to show that science is always, ALWAYS, a process. What is common knowledge today may be invalidated as foolish nonsense tomorrow.

There's a lesson here for those who put too much stock in the wisdom of science.

Klein Verzet zei

I've been into astronomy and the physics thereof since I was a kid

Yes, me too. But lately I've been a bit turned off. The whole M-theory, multiverse farrago is taking the (current) math passed the point where we can match theory with observation. It has entered the realm of pure conjecture.

But stuff like that of Carati is making me come back to the subject. I've been doing a lot of reading and browsing on fractal universes and MOND theory. They're intriguing subjects, even if the main-stream is rejecting it as fringe. At least they don't need an aberration like DM to explain the visible universe.

Klein Verzet zei

I don't quite know what to make of Gingrich. On the one hand he's an absolute hero for his statement that Palestinians are an 'invented people'.

But I do remember him appearing in a commercial with Nancy Pelosi (FFS!) endorsing the green agenda and AGW.

I get the impression that most tea-partiers consider him part of Big Politics, part of the problem in Washington.

Having said that, he may be a more robust candidate then Romney or Perry.

I just wish Fred Thompson would give it another try...

Fredy zei

Indeed Fred Thompson seemed a very solid guy (although I
know little about him). But in the current field, the policy proposals of
Gingrich seem to be the most aggressive in fighting big government and
political Islam.

But I’ve seen those videos as well. I thought they were very
funny for showing his political turn(s!). This could lead one to conclude that Gingrich
is more a kind of political operator than a man of strong convictions. But so
far, I give him the benefit of the doubt, as he has given his (strong) political
views now consistently for year, even if that brings him into what many believe
to be unpopular and political dangerous terrain (like his Palestinian statements).
We should also not forget that he made those global warming statements at a
moment in time that the proposed remedies were still mundane and that the
hysteria was nothing like that of today.

DP111 zei

Question: Is there any reason why the disposition of galaxies is fractal?

Klein Verzet zei

I've no formal answer. In nature it is a common occurrence for self-organizing dynamic systems to display fractal characteristics.

DP111 zei

Thanks KV.

"self-organizing dynamic systems"