51. The God of the Bible is No Delusion!

Comment #68965 by Geraint on September 9, 2007 at 10:03 am

A comment by David Deutsch - the Oxford quantum computing specialist - on his website at www.qubit.org (site is presently unresponsive, so I can't cite the exact link, sorry), notes a similarity that was observed, betwen the large-scale variations in the CMB, and the outline of the continents on the surface of Earth.

Continents? That's nothing. In the ILC map from the one year WMAP data, one can clearly see Stephen Hawking's initials; who's in charge now, eh?

In case you don't believe me, it's the topmost of the three images on this page:
CMB maps link.

You can see SH to the left of centre, just above the middle.

Your brain strains to make out familiar structure in random fields.

The 'axis of evil' is something of a curiosity. Even if it turns out not to be an effect of galactic foregrounds, as statistical flukes go the alignment isn't desperately unlikely. Certainly not likely enough to justify publishing the results under normal circumstances, but in this case collecting more data won't help (the statistical error is limited by the fact we only get to see one sky, not by the quality or quantity of the data), and there had already been some curious features of the low-l CMB noted (basically lower power than expected, leading people to wonder about non-trivial topology; again, the power deficit isn't that statistically significant).

I definitely wouldn't worry about those particular galaxy survey results yet either. As things stand, Steve's comments are essentially justified. One could argue that the mechanism of inflation, or whatever process does the same job, isn't yet known. The CMB results are consistent with inflation, but the current generation of results doesn't constrain the various inflation models particularly well, hence the continuing debate. It's somewhat like the case a few years ago with a proliferation of different cosmological models, most of which were eliminated by new data. A healthy situation.

52. Honest Mistakes or Willful Mendacity

Comment #68163 by Geraint on September 6, 2007 at 9:19 am

No doubt clunking sarcasm about a position your opposite number doesn't hold, like

Tell that to a teenager dying of cancer, and his family.

is what passes for featherlight footwork among theists.

53. A hole lot of nothing found by astronomers

Comment #66162 by Geraint on August 29, 2007 at 5:58 am

Ah, sorry for introducing jargon. The number of sigmas is just a measure of how confident you are that a detection isn't a statistical fluke. 2-sigma corresponds to about 95% confidence, 5-sigma to about 99.99994% confidence. I guess this board isn't a place to write an essay on statistics.

54. A hole lot of nothing found by astronomers

Comment #66079 by Geraint on August 28, 2007 at 11:39 am

Hi Lee,

As pissinintothewind has pointed out, you misattributed his comments to me.

There has already been some evidence of structures more extreme than we expect, notably a massive supercluster of galaxies seen in galaxy redshift surveys that would also have to be a statistical freak to fit in with current models. But statistical freaks do happen. That's why particle physicists need a 'five sigma' result to confirm the detection of new particles, or whatever. They do say that 95% of two-sigma results turn out to be wrong!

There are enough difficulties linking observations to theoretical models that a study of any single object won't make me lose sleep about whether the current standard model of cosmology is correct.

You also have to bear in mind that this model contains quite a few different parts: there's the matter/energy content of the Universe (how much dark matter, how many baryons, etc.); there's the initial conditions (what are the properties of the original 'seed' fluctuations within this matter?); and there are the physical laws and astrophysical processes themselves. A problem with the model could be within any one of those parts, rather than with the whole big bang paradigm.

In the standard model the initial perturbations are self-similar. I haven't had time to read Labini's papers so I don't know how what he's proposing is different. Certainly there are plenty of people studying the topology of large-scale structure, with better data than were available from the Labini papers I can find.

55. A hole lot of nothing found by astronomers

Comment #65865 by Geraint on August 27, 2007 at 6:58 am

Well, it has to be said the article was a bit misleading. The phrase "no stars, no galaxies, no black holes, no dark matter" is totally unjustified by the rest of the text (and by the original paper). Even the actual result is one where it's worth sitting back for a while and waiting for some confirmation.

56. A hole lot of nothing found by astronomers

Comment #65794 by Geraint on August 26, 2007 at 4:12 pm

What do Astrophysicists mean when they say "Nothing"?

On these scales, we trace the distribution of matter by looking at the distribution of galaxies. So when we talk about a 'void' it means a region of space where there are no galaxies large enough to be visible (or, as here, it can mean a region where the density of galaxies is a lot lower than average).

A void isn't an exotic phenomenon; if you plot the distribution of galaxies in 3D from various surveys, you see that galaxies tend to lie in clusters, filaments and walls (your eyes mainly pick out the filaments) with voids in between. Galaxies aren't dotted about randomly. In fact, this rather beautiful 'cosmic web' can be reproduced in simulations that just track the evolution of matter under gravity. Here is a slice through such a simulation (the box is approximately 6 billion light years on a side). The only special thing about the void mentioned in the article is that it seems to be especially large: larger than we typically see in the simulation I linked to, for example. It could just be a statistical fluke, or there could be some effect at work that's unaccounted for in simulations (or the cosmological parameters might be a bit different than appears from other experiments).

Of course, being devoid of galaxies doesn't mean the region is totally empty. A galaxy can only form at a sufficiently large, sufficiently dense concentration of mass. It's like looking at the night-side of the Earth from space, and using the lights from buildings to trace out where the people are. You can only really see the big cities, not individual farmhouses out in the countryside. But that doesn't mean there aren't people outside of the cities.

Black holes don't really have anything to do with it. And just to correct the following:

If I recall correctly, black holes' gravitational forces work relatively close range compared with other stellar bodies, otherwise wouldn't our solar system be quickly spiraling in towards the galactic core (super-massive black hole) of the Milky Way?

The gravitational force from a black hole falls off as an inverse square, identically to any other body. If you're some large distance from a black hole of 1000 solar masses, you feel just the same force as if you were at the same distance from a star cluster totalling 1000 solar masses. The difference with a black hole is that this mass is contained in a very small volume: when you get very close, the intense field leads to all of the black hole strangeness that people know about.

The only reason that the effect of the galaxy's supermassive black hole is only noticeable when you get close to it, is simply that the mass of the black hole is small compared to the mass of the rest of the galaxy.

57. New age therapies cause 'retreat from reason'

Comment #62220 by Geraint on August 9, 2007 at 12:49 am

Chance predicts success after about 5 goes (1 in 12 of getting it the first time + 1 in 11 the second time [unless they're blockheads who guess the same again] + 1 in 10 the third time + 1/9 + 1/8 = 0.51).

Not the correct way to do the calculation. You can see this if you carry on adding the fractions and get a probability >1 that they get it in nine tries.

58. The Panel

Comment #53427 by Geraint on July 1, 2007 at 12:21 pm

What on Earth was the 'answer' to the lightbulb question meant to be all about? Electrons visiting a power station and 'picking up energy'? Uh? The question was also vague.

I agree that it's the scientists' answers that are the most shocking. I can't imagine scientists trying to communicate with the public when they're all at sea outside their own little specialism.

I'm not surprised that Will Self did fairly well, especially compared to the other writers and broadcasters. I might even have expected better. But the others were just pathetic.