Chris Lintott’s Universe

Inspired by this paper a few of us at UCL have begun thinking through some of the problems. I’ll try and summarize things here as I think that attempting to answer some of these fundamental questions provides a nice illustration of what we do and do not know.

The first problem George Ellis brings up is the simple fact of the uniqueness of the Universe. This has profound consequences; cosmology on the largest scale is not an experimental science (we can’t rerun the history of the Universe and see what happens) and it is not even a comparable one in the way that, say, galaxy formation is. If you want to know how galaxies form you can compare many different galaxies, each of which evolved more or less independently.

This means that it’s impossible to establish large-scale laws of physics for the Universe. For example, it is a fundamental assumption of modern cosmology that the Universe is homogeneous, with material smoothly distributed on the largest scales. Although we can imagine testing the extent to which this is true, we will never be able to establish whether this had to have been so, or whether it’s just a cosmic coincidence.

This issue comes up a lot already. The results from WMAP’s studies of the cosmic microwave background indicate that there is less power than expected on large scales. Is this an example of ‘cosmic variance’ – our Universe just happening to be different from the ‘average’ on these large scales?

But there’s another problem. I’ve talked about our Universe being ‘average’ but from our perspective within it it is the only one we can ever experience, see or test. How, then, do we define average?

This sort of reasoning does not threaten the conclusions of the currently standard cosmological model, but it does challenge us to think carefully about the limits on our knowledge. There will be much more to come over the next few months on this subject, so please comment and let me know if you’re interested (or not!).

Following a couple of requests, I’ve put the pdf versions of the powerpoint to two popular talks online, should anyone want a look.

Cosmology for the Terrified
The First Stars

In response to a comment left on a post below, yes it was very windy in Hawai’i which did interfere with the seeing conditions (as did the nearly full moon on that trip). More generally, though, what professionals want from an observing site can be different from amateur requirements. Most modern large optical telescopes allow a breeze to pass through the telescope – you can see the slits designed for just this purpose on this picture of the VLT. This helps to keep seeing steady and the mirrors clean, but of course a strong breeze is severely detrimental to a small telescope with a closed tube, as Damian found out when trying to image from just next to the VLT.

On the summit of Mauna Kea, with the Moon out of the way the sky is stunning. But only when you hyperventilate a little to get enough oxygen into your lungs – otherwise the altitude ensures the sky is somewhat disappointing. The best views I’ve had from Hawai’i have been down at the lodge when you can walk out of a fully lit room and see the Milky Way straight away.

Update : Thanks to Kaustav Bhattachar for pointing out my broken links. It all works now.

It’s probably a little late to plug this, but a round of comments on the Hawaii program reminded me to say that the last repeat of the Hawai’i program is on BBC2 on Saturday, at 12.45. All comments welcome.

That means that January’s program should be online soon, along with the last few year’s worth.

This story, well-handled in both the Guardian and the BBC, has been brewing for a while. Gerry Gilmore told us a little about the results back in November 2004 when we filmed the Chile program, but it’s still slightly shocking to see in print. The following all comes with the disclaimer that there doesn’t appear to be a paper yet available.

The fact that there is much missing mass in the Universe has been known for decades – the classic indicator is the fact the spiral galaxies don’t rotate as you’d expect if the luminous disk contained all the matter. For years the arguments raged between those who believed in MACHOs (MAssive Compact Halo Objects – ie many small, faint planets or other blobs of normal matter) and WIMPs (Weakly Interacting Massive Particles). Eventually, surveys suggested that there was no evidence for MACHOs and so we were left with a mysterious particle which had only been detected via its gravitational influence on the rest of the Universe. Large simulations, like these appeared to confirm that whatever the dark matter was, it had to be cold – able to form small clumps – otherwise it seemed impossible to produce a Universe that looks like the one around us.

That last result is what these new observations, of small galaxies surrounding the Milky Way, cast doubt on. By studying the way the stars in these structures are influenced by the dark matter, the researchers were able to build up an idea of where it is. They found that essentially it lies in large blocks, and refuses to split into smaller chunks in order to agree with the simulations. This isn’t a blow for dark matter per se – we’re just learning more about how it actually behaves, about its physics. But it is a problem for our nice models of how galaxies form around the dark matter, and it will be interesting to see how the modellers respond.

It’s also my feeling that this is a boost for those working on MOND – modifying the theory of gravity to get rid of the need for extra particles, although you’d need to be more of a MOND expert than I to comment on whether this result is reproducible by MOND.

In short – isn’t it great when the Universe isn’t as we expect?

Reading about the closure of the London Planetarium in the Independent yesterday struck me as just sad. It’s fair to say that I haven’t paid it much attention since visiting five or so years ago, which is a terrible indictment in itself, I suppose.

Then Today rang and invited me to go and see a show and comment. Which is where I started receiving unpleasant surprises. For starters, the show is now 15 minutes (if that) instead of the full 45 minutes or an hour, and is part of the whole Tussauds package. That means that it costs something like £18 (the figure I was quoted as an ‘average’ adult price) to get in. When you do, there is no attempt to put the planetarium in context with the rest of the exhibits, it just stands as a ‘take it or leave it’ proposition. In these circumstances, it’s not surprising that ‘only’ 30% of visitors take up the chance to see the show (mind you, that’s still something like 600,000 people a year).

The show itself was okay, but it wasn’t a planetarium show. There was not a single reference to the night sky, but instead a rapid tour through the solar system which, while it looked good will fail to impress anyone who has ever been in an IMAX. It was obviously designed to be played on a loop with no need for updating, topical references and information or the input of any astronomers. At over £1 a minute per person, is there any wonder that they’re not getting the kind of regular visitors that they used to, back when a trip to the planetarium was the cost of a cinema ticket.

Now, obviously Tussauds are a commercial organisation, and what they do with their space is sadly their business. But having run the planetarium into the ground, moved it so far away from what a planetarium should and could be (especially given such an incredible building) to blame the closure on a lack of public interest really sticks in my throat. I hope that came across on the radio this morning, even it has been swallowed by the Guardian in today’s leader.

For the record, the reason the Today program piece was twseparatete interviews was because Tussauds refused to have a conversation with me on air.

Greenwich have a new planetarium opening next year. I can’t wait.

This makes me extremely angry. And it’s dangerous too. In the US, when the religious lobby attempt to import creationism into science classes, there’s the constitutionally defined separation between church and state to fall back on, and so it is sufficient to demonstrate in court that Intellegent Design/Creationism is not science. British schools have no such protection, and if the government really does intend to hand over some say about the curriculum to private bodies we might be dealing with groups of British schoolchildren being fundamentally mislead over the status of evolutionary theories sooner than you might think.

Rather than rebut everything myself, have a look at the excellent Panda’s Thumb, especially the record of Fuller’s comments in the trial itself.

Rant to the Guardian follows. It’s only this short because it’s early, and I have a job interview to prepare for.

Dear Sir

I was disturbed to see the coverage awarded to Prof Fuller in today’s Education Guardian, a feeling accentuated by the uncritical nature of the report. To take a single example, Fuller is allowed to claim that despite his pro-’Intellegent Design’ stance that he ‘draws the line at
creationism’. However, one of the main conclusions to emerge from the recent trial in Dover, Pennsylvania was that ID is merely a foil for creationists seeking a new way to work their philosophy into science classes. The first book to systematically use the term ‘intellegent
design’, ‘Of Pandas and People’, was created (intellegently or otherwise) from its predecessors simply by judicious use of the find and replace function, turning every mention of the word ‘creationism’ with ‘intellegent design’. Good marketing, but ID is no more science than
creationism, and to draw a distinction between the two is simply misleading.

Prof Fuller also points out that ‘if you were having a science studies class, all the things I was saying would be completely normal’. Here we agree, but if he wants to campaign to introduce science studies into the school curriculum shouldn’t he do that directly instead of subverting
biology?

An excellent lecture last night at the BAA by Doug Ellison who is doing incredible things with images from the Mars rovers, Spirit and Opportunity. He highlighted a result I hadn’t seen before – Spirit’s image of the Orion Nebula. It may not look much, but astronomy from the surface of another planet impressed me!

A wonderful sequence of images from Pete Lawrence obtained as part of the Sun program filming yesterday. Using a hydrogen-alpha filter it was possible to view the gas 2000km or so above the visible surface of the Sun (the ‘photosphere’) and see the kind of prominences only normally on show at an eclipse.

We also got to use a calcium filter provided by John Adair, which was a new experience for me and showed sunspot groups in the process of changing and evolving.

Have been filming for the BBC4 special on the Sun – to be broadcast on the 20th February as part of a two-part series (the other is on the Moon, was filmed earlier in the year and is excellent) – which included an interview with Fred Espernak. He showed us what I think is the best picture of totality I’ve ever seen.

It was taken from the deck of a ship in the Pacific in an extremely short totality (less than minute) and is a composite of seven different shots. The ship apparently was rocking all over the place and Fred didn’t even get a chance to look at the Sun. For Turkey in March I won’t be ruining my second totality (and hopefully the first clear one) by looking through a viewfinder. He’s seen fourteen, so I’m glad he missed this one visually.

incidentally, I’d like to hear from anyone who is going to be viewing the March eclipse as part of our preparation for the program we’re making about it. Just leave a note in the comments or drop me an email.