Balls on a trampoline, alligator wrestling and forgetting your keys: Marcus Chown has the answers.

A while ago I offered readers the chance to ask tricky questions of cosmologist and author Marcus Chown.  The questions were exactly what I would expect of my astute and intelligent readership.  Read on to find out what Marcus has to say in response.

Graham said:
OK. Marcus, we hear from scientists so often that “you’d have to know maths to be really able to understand the theory”. Frankly, this always seems a bit feeble. Maths is just a way of expressing reasoning. I suspect what it actually means is that many scientists are not actually able to explain the concepts they deal with but are content to leave this mystery at the heart of what they do and ‘merely’ manipulate the ideas mathematically, almost mechanically. Do you feel there is any truth in this?

Marcus said:
Hi, Graham. I agree with you but I also agree with the scientists! For a reason no one really understands the language of the Universe does appear to be mathematics. It has led some to speculate that, if there is a God, He must be a mathematician! Because the laws of physics are fundamentally mathematical, it is those mathematical laws that most accurately capture reality. This is, of course, why some scientists say you cannot understand things without the maths. But, of course, there are degrees of understanding. Mathematics is simply the best metaphor for physical reality. We can write down Newton’s laws of motion, for instance, and they perfectly model how a ball flies through the air under gravity. But the fact that mathematics is the best metaphor does not mean that we cannot use cruder metaphors than mathematics to help us understand things – visual pictures, for instance. This is what I try and do in my books.

Admittedly, the only way to completely understand, for instance, Einstein’s theory of gravity is through Einstein’s equations. However, we can still imagine a heavy ball placed on a trampoline creating a depression around it and a smaller ball falling into it. This is a good metaphor for how the Sun warps the surrounding space-time and other bodies fall towards it. It may not be as perfect a metaphor as the mathematical equations but it conveys the essential features of what is going on.

You are right that some physicists merely manipulate ideas mathematically. But others, most notably, the Nobel-prizewinner Richard Feynman, thought very visually. Whereas Julian Schwinger, who shared the prize with Feynman, covered pages and pages with mathematical equations to decribe how matter interacts light, Feynman famously created simple pictures – Feynman diagrams – which encapsulated the essence of what was going on.
Gary said:
Hi Marcus!  You’re a brave man.  Is it possible someone will one day write a New Scientist article which does not conclude that, “more research is needed”?
I look forward to the day someone writes something along the lines of, “Actually the sex life of the lesser spotted garden snail is kind of lame and boring, so let’s spend the next research funds on something more important.”

Marcus said:

Hi, Gary. I don’t think I’m that brave. I’m not exactly offering to wrestle alligators!

I think it might be a sad day when no more research is needed. We will have come to the end of science, with nothing else to discover!

Science is provisional. It’s the best description of reality – or particular aspects of reality – we have at the moment. Scientists are always hoping to find something that doesn’t fit the standard picture and so points the way to a deeper, more fundamental theory. At the moment, for instance, we know that Einstein’s theory of gravity, though hugely successful, is an approximation of a deeper theory. We know this because it breaks down in two places – at the heart of a black hole and at the birth of the Universe. It predicts a “singularity”, when things like temperature skyrocket to infinity. A singularity is an indication that a theory has broken down, that it has been stretched into a domain where it no longer has anything sensible to say. Physicists think that, if they could unite Einstein’s theory of gravity with quantum theory – our description of atoms and their constituents – the singularities would go away. Quantum gravity – the name given to this umbrella theory – would therefore provide a window on a deeper level of reality.

Of course, it could be that there’s a level below that, and one below that, and nature is like a series of Russian dolls which we will never get to the end of! Physicists are fond of talking of their quest for a “theory of everything”, that encapsulates everything about the Universe in one neat set of equations. But, of course, if we ever get such a theory, we will still be left with the question: Why that set of equations rather than any other?! Our questions may never end, which means scientists will always have jobs!

Ruzkin said:
Hi Marcus! It’s fantastic that you’re offering yourself up to the masses like this. A question that’s perhaps a little off-kilter – if we somehow, one day, dug through the mysteries of physics and nature and pi and discovered the universal message at the heart of all creation… what would you LIKE it to be? What, in your opinion, would be the raddest hidden message of all?

Marcus said:

Hi, Ruzkin, you’re very welcome. That’s an interesting question. It is also interesting that you mention pi. In Carl Sagan’s science fiction novel, “Contact”, which was made into a movie starring Jodie Foster, people calculate pi to trillions upon trillions of digits and suddenly find that the numbers stop being random and start being a sequence of 0s and 1s, encoding a message left by the creator of the Universe! Sorry, that’s not too relevant to your question, but you just reminded me of that book.

What would I like the message at the heart of creation to be? That’s a BIG question. I’m not a religious person but I think I’d like to discover that life has some important role to play in the Universe and is not just incidental. American physicist Frank Tipler certainly thinks this. In his book, The Physics of Immortality, he claimed that it was inevitable that life would one day gain control of the cosmos and engineer the so-called Omega Point universe, the only one permitted by Einstein’s theory of gravity in which life can survive forever.  I write about this in my book, The Never-Ending Days of Being Dead. I’m not sure if I believe it but it’s a fantastically mind-blowing idea.

Ruzkin also said:
Failing that, how does it feel to know that your book has not just entertained folk around the world, but shaped the fundamental way they look at the universe and their lives?

Marcus said:

That is the most amazingly brilliant thing. I was very, very fortunate to go to, for instance, Caltech in California, where I was taught by people like Nobel prizewinner Richard Feynman and learnt amazing things. If I can communicate some of what I learnt to people who haven’t been as lucky as me, I am really, really pleased. It is very humbling to hear from readers that I have overcome their fear of, say, quantum theory, helped them appreciate what an incredible universe we find ourselves in, and given them the confidence to read and find out more.

Kate said:
Grappling with the idea of infinite universes with a finite number of histories – when physicists talk about all us having doubles, how literal is that? I understand the principle of there only being a certain number of ways to arrange protons, but does that mean that 10^10^28 away is someone who looks and acts like me, with a similar life history? Or does it just mean a similar arrangement of protons i.e. something vaguely humanoid? Equally with “everything having happened somewhere”, is that at the level of forgetting/not forgetting keys or the development of planets? That poorly-phrased question is the sound of my mind being blown!

Marcus said:

Hi, Kate. Not poorly phrased at all. And, yes, it is completely literal! An unavoidable consequence of the standard picture of our Universe combined with our standard picture of physics is that there are infinite number of copies of you out there, who until this moment have led identical lives to you. So, yes, we are talking about everything happening at the level of “forgetting/not forgetting keys”. This is cosmology’s dirty little secret, the thing cosmologists rarely mention. In fact, most would rather sweep it under the carpet and not think about it at all.

Some physicists, such as Alex Vilenkin, are completely OK with the idea, though. They say nature has seen fit to take the pattern of a star, for instance, and repeat it countless quadrillion times. Why not whole universes? It may seem quite wasteful but Vilenkin says the universe is under no obligation to respect our sensibilities. It is the way it is and we just have to put up with it (See Vilenkin’s excellent book, “Many Worlds in One: The Search for Other Universes”).

Of course, it could be that there is something wrong with either the standard picture of our Universe or our standard picture of physics or both. That would certainly be a way out of the conclusion that out across the universe there are an infinite number of copies of you reading an infinite number of copies of this interview and thinking: What the hell is that Marcus Chown banging on about?!

Merrilee said:
How big do you think am interstellar body would have to be to retain or develop some sort of atmosphere?

Marcus said:

That’s an interesting question, Merrilee. The answer is: it depends! There are basically two factors at work here. On the one hand, there are the gas molecules in an atmosphere flying about and desperately trying to escape into space. And, on the other hand, there is the gravity of a body pulling on those gas molecules and trying to stop them flying off into space. So, the faster the molecules are moving – which is the same as saying the hotter the atmosphere – the bigger the planet must be so that its gravity can hold on to them. The Earth, for instance, is big enough to hold onto a relatively thick atmosphere for billions of years; the Moon, which about 1/80 the mass, with only 1/6th the Earth’s gravity, cannot. But does that mean that small bodies like the Moon cannot have atmospheres? No! Because, as you move out through the Solar System, and further away from the Sun, it gets colder. That means that the molecules in a body’s atmosphere are moving more sluggishly, so a small body with weaker gravity can still hold on to them. We see this effect with Saturn’s moon, Titan, which is far smaller than the Earth and yet has a thick atmosphere which at its surface is four times denser than the Earth’s. So, in theory, any body, no matter how small, could have an atmosphere, as long as it is far enough away from the Sun.

Actually, other factors are also involved such as whether a body has a magnetic field. This acts like a planetary shield and prevents the solar wind – a million-mile-an-hour hurricane that blows out from the Sun – stripping away an atmosphere. Mars, for instance, being smaller than the Earth, cooled more quickly after its birth, its molten interior solidifying. It is electrical currents circulating in a molten core that generate a planet’s magnetic fields. So, without such a protective field, the solar wind has stripped Mars of the atmosphere we know it once had from the evidence of ancient river channels.

Merrilee also said:
2. You’ve explained so many complicated theories in your book, in a way that any person can understand. But are there any theories out there that boggle your mind? Any ideas that make you think that some of your peers are completely bonkers?

Marcus said:

Everything boggles my mind! That’s what’s so exciting about science today. We have discovered that the Universe we live in is stranger than science fiction, far weirder than anything we could have invented. For instance, we live in a universe where a single atom can be in two places at once, the equivalent of you being in Perth and Sydney at the same time; where matter is so empty that, if you squeezed all the empty space out of it, you could fit the entire human race in the volume of a sugar cube; where the ultimate building blocks of matter may, according to string theory, be like ultra-tiny violin strings vibrating in a space-time of ten dimensions.

Neils Bohr, the great Danish quantum physicist and sparring partner of Einstein one said to someone: “Your idea is crazy. The question is: is it crazy enough to be true?”

We live in a crazy universe. And one thing appears to be certain, and that is physics in the future is likely to get ever more bonkers, ever more counterintuitive. Because, well, that’s just the way the Universe appears to be.

Merrilee said:

Thanks, Marcus for taking the time to answer our questions!

Marcus said:

Thank you, Merrilee! Really enjoyed answering some excellent questions!

If you want to find out more about Marcus’s books, check out his website.  And for those of you with kids, Marcus has written a children’s book: Felicity Frobisher and the Three-Headed Aldeberan Dust Devil.

6 thoughts on “Balls on a trampoline, alligator wrestling and forgetting your keys: Marcus Chown has the answers.

  1. Fascinating post, Merrilee. I’m glad to be introduced to Marcus’ work and will have to check it out. My husband is working on his PhD in physics as we speak, and he’s one of those weirdos who does it all by manipulating the numbers — but he does understand what he’s talking about and has a passion for explaining the exciting wonders to us lesser mortals. ;)

    (How he ended up with me, a woman who barely manages to balance her checkbook and hates life by the numbers, is a mystery only physics — or perhaps some form of mysticism — could hope to explain one day!)

  2. Thanks for the reply Marcus, and it’s good to meet you, if only via electrons, after having read so many of your articles.

    I think you’ve tiptoed around my question though. No one could doubt your example that checking relativity is important. The point is that a noticable proportion of research funds is going to stuff which is patently unimportant, such as the proverbial sex life of the lesser spotted garden snail.

    Good luck with the book!

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