Shahn Majid

After last week’s imaginative speculation, I’d better tell you something concrete. How about the solution to quantum gravity that has been eluding us for some 90 years? Here it is … er … with one minor catch. We’ll have to suppose that spacetime is 3 dimensional, i.e. one time and only two space directions rather than three.

He's never heard of this "3rd spatial dimension"!

There is a tradition, starting I think with Edwin A. Abbott’s 1880 tale ‘Flatland’, where we suppose that we are not 3-dimensional beings but, let us say, ants, constrained to live forever on some two-dimensional surface. We tend to visualize a surface — imagine, say, the surface of a sphere or doughnut — within three dimensions, but don’t be fooled by that. That is just an aid to visualization. An ant crawling about on the surface, moving along ’shortest paths’ (the analogue of a straight line on a flat space) could fully map out the geometry of the surface without ever leaving it.

I am speaking here of the spatial geometry. We will assume that time is a further linear dimension, making spacetime 3-dimensional, mapped out as the 2-dimensional surface evolves in time.

Actually, we won’t assume any of this, since as I explained in previous blogs, there is no evidence of an actual spacetime continuum of any dimension. But we will take it as a commonly accepted starting point and then I will explain carefully where we have to make the quantum leap to throw all that away to get to actual quantum gravity. This will also give you a bit of insight into the guts of the way that scientific revolutions work in practice.

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Shahn Majid looks at dark energy. Will it herald a revolution in our understanding of fundamental physics?

CREDIT: NASA

Last week I explained what I argue to be the greatest theoretical challenge facing fundamental physics today; that the very concept of the spacetime continuum is flawed and in need of revision. This week I want to explain what I think is the very greatest challenge coming from the experimental and observational side. Science thrives on a dialogue between theory and experiment and when you put all this together you arrive, as I see it, at the most exciting time for theoretical physics for a century, perhaps even since the 17th century in terms of the expected level of shake-up.

The experiments and observations that I refer to do not relate to the Large Hardon Collider. While that should be interesting especially if they don’t find the Higgs particle … well the LHC is now broken for a few months and that gives us a chance to see what else is going on. What is going on is the possibility of testing physics at the Planck scale, i.e. at energies 10 million billion times greater than the LHC could ever produce. It’s a brand new field, hitherto considered by physicists completely impossible, called ‘quantum gravity phenomenology’.

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There is more subtlety to the evolutionism/creationism debate than many of the loudest voices tend to employ.

Continuing his exploration of space and time, Shahn Majid takes a look at science, religious belief, what we really know, and draws the line in the context of fundamental physics.

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It was the best of times, it was the worst of times; it was the age of wisdom, it was the age of foolishness; it was the epoch of belief, it was the epoch of incredulity.

-Charles Dickens

Last week the director of education for the UK Royal Society, Professor Michael Reiss, resigned after he was criticised for being ambiguous about the correct response to creationism, and to religion in general, if brought up by a pupil in a high-school science lesson. Perhaps his words touched upon a raw nerve in the scientific community or perhaps the point he wanted to make was just too subtle to be understood by the media in these troubled times.

Professor Reiss, who is also a Church of England minister, apparently suggested that in his experience it was more effective in such a situation to discuss creationism in the science class if only to show that evolution fits the facts better. Critics said that he should have had the teacher simply refer the pupil to religious education classes as creationism is not a scientific theory at all. Professor Reiss himself has stated that creationism is a `world view’ and that you have to discuss it to get through to pupils with such beliefs.

Was it over-reaction? A defender of Professor Reiss’ position on the BBC radio I heard argued that the creation myth was a metaphor, not to be taken literally. Hence scientists should not be so touchy. A critic could argue, however that if that were the case then that is exactly why the teacher should indeed to refer the pupil to poetry, drama or religious studies where parables as metaphor are appropriate. The problem is that as soon as you bring it into a science lesson you risk confusing science and parable. This is not helped by creationists who insist that the creation myth is not a parable but true and should at the very least be taught as a valid theory alongside evolution. This then makes a mockery of science.

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What is God’s relation to space and time? Is there a way of reconciling theology and physics?

John Polkinghorne

Time is much more mysterious than space. We can move around or stand still at will, but no one can travel in time or arrest its inexorable flow. Or so it seems to us. Yet there are people who believe that the passage of time is no more than a trick of human psychological perspective and the real nature of temporality is what is called ‘the block universe’, the spacetime continuum as a whole, considered ‘all at once’. They appeal to the fact that relativity theory tells us that different observers make different judgments of the simultaneity of distance events. If that is so, does it not mean that the apparent difference between past, present, and future is in reality illusory?

Well, actually, no.

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The European Organization for Nuclear Research [CERN] has their Large Hadron Collider [LHC] up and running. The first test-fire was successful. A lot of fearful people fearing the creation of a super-massive black hole are calmer now. Should they be?

In his next post, Majid weighs in on the science vs. religion debate the best way he knows how: not as an evolutionary biologist, but as a physicist. Read it here >>

[UPDATE]: Great to see so many questions in the comments section, which I, of course, am not qualified to address. I’ve contacted Dr. Majid to see if he wishes to answer to any of them. Keep ‘em coming!

[UPDATE #2] Please see Dr. Majid’s comment below in response to some of your questions.

Shahn Majid put together Cambridge’s On Space and Time and is Professor of Mathematics at Queen Mary, London. He’ll be filling us in on why these taken-for-granted dimensions of reality hold so much fascination for physicists, mathematicians, theologians, and philosophers.

[UPDATE From Dr. Majid - 4:30 EST]

Without spoiling the fun of the piece, I should probably add that I do firmly count myself among those that say ‘no’, LHC definitely won’t produce a giant black hole that swallows up the Earth. For one thing, the circumstantial evidence is overwhelming — much more energetic collisions occur all the time out there in the Universe at large and astronomers don’t see them producing black holes. However, the theoretical issues about the possible production of black-holes and what exactly happens to them if they are produced is a fascinating story that takes us to the edge of our understanding of the structure of space and time …

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There’s nothing like the prospect of imminent death to get you interested, especially considering the usual public interest in hard-core particle physics. This week it was the switch on of the Large Hadron Collider in CERN, Geneva. The BBC, at least, was quick to denounce reports that this might result in the creation of black holes that might coalesce and grow, eventually swallowing up the entire Earth and in the process destroying life and civilisation as we know it.

View the nasty footage here.

So that’s what all the fuss is about.

Actually, there will be two particle beams, going in different directions, and only once both of these are working will CERN scientists actually collide them and possibly create black holes. So we don’t know yet. Should we be worried?

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