The Big Bang Exploded?

I suspect that I’m not the only physicist who receives unsolicited correspondence from people with wacky views on Life, the Universe and Everything. Being a cosmologist, I probably get more of this stuff than those working in less speculative branches of physics. Because I’ve written a few things that appeared in the public domain, I probably even get more than most cosmologists (except the really famous ones of course).

Many “alternative” cosmologists have now discovered email, and indeed the comments box on this blog, but there are still a lot who send their ideas through regular post. Whenever I get a envelope with an address on it that has been typed by an old-fashioned typewriter it’s a dead giveaway that it’s going to be one of those. Sometimes they are just letters (typed or handwritten), but sometimes they are complete manuscripts often with wonderfully batty illustrations. I remember one called Dark Matter, The Great Pyramid and the Theory of Crystal Healing. I used to have an entire filing cabinet filled with things like his, but I took the opportunity of moving from Cardiff some time ago to throw most of them out.

One particular correspondent started writing to me after the publication of my little book, Cosmology: A Very Short Introduction. This chap sent a terse letter to me pointing out that the Big Bang theory was obviously completely wrong. The reason was obvious to anyone who understood thermodynamics. He had spent a lifetime designing high-quality refrigeration equipment and therefore knew what he was talking about (or so he said). He even sent me this booklet about his ideas, which for some reason I have neglected to send for recycling:

His point was that, according to the Big Bang theory, the Universe cools as it expands. Its current temperature is about 3 Kelvin (-270 Celsius or thereabouts) but it is now expanding and cooling. Turning the clock back gives a Universe that was hotter when it was younger. He thought this was all wrong.

The argument is false, my correspondent asserted, because the Universe – by definition – hasn’t got any surroundings and therefore isn’t expanding into anything. Since it isn’t pushing against anything it can’t do any work. The internal energy of the gas must therefore remain constant and since the internal energy of an ideal gas is only a function of its temperature, the expansion of the Universe must therefore be at a constant temperature (i.e. isothermal, rather than adiabatic). He backed up his argument with bona fide experimental results on the free expansion of gases.

I didn’t reply and filed the letter away. Another came, and I did likewise. Increasingly overcome by some form of apoplexy his letters got ruder and ruder, eventually blaming me for the decline of the British education system and demanding that I be fired from my job. Finally, he wrote to the President of the Royal Society demanding that I be “struck off” and forbidden (on grounds of incompetence) ever to teach thermodynamics in a University. The copies of the letters he sent me are still will the pamphlet.

I don’t agree with him that the Big Bang is wrong, but I’ve never had the energy to reply to his rather belligerent letters. However, I think it might be fun to turn this into a little competition, so here’s a challenge for you: provide the clearest and most succint explanation of why the temperature of the expanding Universe does fall with time, despite what my correspondent thought.

Answers via the comment box please!

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17 Responses to “The Big Bang Exploded?”

  1. Anton Garrett Says:

    This chap reminds me that the best (albeit wrong) arguments against relativity generally come from engineers, because engineers have an intuition better developed in Newtonian mechanics than anybody else, and they know how to argue logically. The problem is that their intuition has never been schooled in objects interacting at speeds close to that of light.

    I recall an article by a mathematician called Underwood Dudley, titled “What to do when the trisector comes”. (Angle trisection using only compass and straightedge was fruitlessly sought for centuries and was eventually proved impossible, but some people still think they have counter-examples.) He said his response was to escalate up a 3-point scale: (1) write a letter of congratulations on the closeness of the approximation, but demonstrate its failure by numerical example; (2) write a letter designed to make the trisector antagonistic to you; and if that didn’t work then (3) put the trisector in contact with other trisectors having different algorithms.

    • telescoper Says:

      Yes, he knows how gases behave when placed in a container which then expands but that’s not really relevant to what’s going on in the cosmological setting.

  2. As the Universe expands, the energy within its bounds remains the same but the energy density reduces as the available volume increases. If there is less energy per unit volume, then the average energy absorption would fall per unit volume and hence the temperature would reduce over time.

  3. stallphill Says:

    In my experience, some of us haven’t clued into the analogy of hot matter confined to the 2D expanding surface of a sphere (expansion without borders…). A very neat model, with adiabatic expansion – air conditioning – cosmological style.

  4. Ah yes, Newtonian mechanics versus relativity… they don’t really play nicely together at the scale of the universe. As I understand it the drop in background temperature is a function of the expansion of the universe (space-time). I keep wishing a ‘Planck’ was a measure of temperature as well as length, because then it would be possible to say that when the Universe was but one Planck-length across, its temperature was at Max Planck. I had to say that…

  5. Since my official name (not the Irish version here ), shares a surname with a female TV investigator of the paranormal, I have had my share of wacky correspondents, one of whom sent me a series of panicky emails, asking me to investigate her neighbours because they were putting implants in her brain and ovaries! She said the Police had suggested me. I contacted the Police and they had infact suggested this lady contact Universities without thinking through the consequences!

    We also suffered from infiltration by weird Brian Cox groupies when I was at Manchester.

  6. The analogy with gas expansion is incorrect since the gas expands into its surroundings while the universe doesn’t, and standard thermodynamics says nothing about systems which expand but don’t have surroundings. Perhaps there is already some miraculous ad hoc thermodynamics that “solves” the problem – cosmologists know no limits.

  7. One should include gravity. The universe has self gravity, a refrigerator gas does not.

  8. As universe expands energy is constant but density falls so no matter how fast a particle moves it gets less likely, on average, for interactions to occur and cause state changes. So state of universe gets kinetically trapped over time. “Frozen”. Can’t change. Eventually will quantum tunnel to ground state.

  9. Expansion is absurd – the universe is STATIC. If there were expansion, there would be deformation of galaxies, due to competition between expansion and gravitational attraction inside galaxies. No deformation observed. Cosmologists have “solved” the problem in the following, not very honest, way:

    Sabine Hossenfelder (in Forbes): “If The Universe Is Expanding, Then Why Aren’t We? The solution of general relativity that describes the expanding universe is a solution on average; it is good only on very large distances. But the solutions that describe galaxies are different – and just don’t expand. It’s not that galaxies expand unnoticeably, they just don’t. The full solution, then, is both stitched together: Expanding space between non-expanding galaxies.”

    • Note that Sabine Hossenfelder is in absolutely no way, shape, form, or fashion stating or implying that the universe is static. She is saying that, while the universe expands, galaxies don’t (nor does Brooklyn).

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