Science Sundays with John Duffield: The Big Bang!

We have good evidence that the universe is expanding, and when you know a bit about relativity and space and energy, you end up reasoning that the universe just has to expand. Space has an innate pressure, and gravity doesn’t suck space in. So the universe expands like a stress ball expands when you open your fist. Easy peasy.

But then you hit the rewind button and think about what the universe would have been like. Then you think about the Big Bang:

Universe

Image Credit: NASA/WMAP Science Team

You sometimes hear that the universe began as a singularity, but actually that isn’t part of Big Bang cosmology. The Wikipedia article is pretty good in this respect. Yes, when you know about the speed of light varying with gravitational potential, you see the sense in likening the early universe to a black hole. But it’s the original frozen star black hole, not the one with a point-singularity in the middle.

Note the word frozen. People tend to say the early universe was hot, but heat is an emergent property of motion. And in a frozen universe, there isn’t any. Yes, the energy density of space must have been high, like it is in a black hole. But like at the event horizon, “gravitational” time dilation must have been infinite. That means there is no motion. So there is no heat. So there is no radiation either, because if radiation doesn’t move, it isn’t radiating.

This early universe where everything is frozen is a strange place. Motion is king, but if there is no motion there is no light. And if there is no light there are no photons. And no electrons too, because we make electrons out of photons in pair production. It’s the same for protons, so there is no matter in the usual sense. And not only that, but clocks “clock up” regular cyclic motion, so without motion, there is no time. It’s hard to say what does exist. You can say energy exists, because that’s the one thing we can neither create nor destroy. But if nothing moves you can’t measure any distance, so does space exist? Maybe it’s space Jim, but not as we know it. It reminds me of the gravastar, where the central region is “a void in the fabric of space and time”. And that reminds me of the black hole depiction by Alain Riazuelo, a Parisian cosmologist. Think of a translucent party balloon, speckled with white dots to represent stars. The skin of the balloon is a 2D analogy for our gin-clear ghostly elastic space, only it’s got a hole in it:

Image credit Alain Riazuelo, see http://fr.wikipedia.org/wiki/Trou_noir

Image credit Alain Riazuelo, see http://fr.wikipedia.org/wiki/Trou_noir

Voila. It’s like a black hole is a hole in space. It’s like the frozen space in the frozen-star black hole isn’t space any more. Like the early universe was like a black hole with nothing outside it. Like it was a hole in space, with no space around it. Like a hole in nothing is something. Like ice isn’t water. But it’s still a place where a fish can’t go? Or a wave can’t go? Answers on a postcard please.

Meanwhile come with me to the dawn of time. We stand together in a bubble of artistic licence in the early universe. There are no photons, there are no atoms, there is no motion, there is no time. Entropy is “sameness”, and everything is the same, so entropy is high. There is no matter, because there are no atoms, there is no light, because there are no photons. There is no gravity, because energy density is homogeneous. And oh, it is dense. There’s lots of energy, because energy is the one thing we can neither create nor destroy. And energy = pressure x volume, so there’s lots of pressure. It is titanic. How it got there, I don’t know. And nor do I know why something happened to release that pressure. Some say God did it, which is a non-answer. That’s just turtles all the way down. Others say a quantum fluctuation did it, but that’s a non-answer too. What exactly “fluctuated” in a frozen universe? Or if you don’t like the frozen universe, what exactly “fluctuated” to create time and space and energy and everything else? I don’t know. Nor do you.

But I do know I like The Last Question by Isaac Asimov. I read it when I was a boy, and his “LET THERE BE LIGHT!” still sends shivers down my spine. I’m not religious or anything, but I do have that cosmic awe, and it runs deep. The best I can suggest is that the big bang was something like lighting the blue touch paper. The early universe was something like a block of C4 explosive. Somehow something happened to unleash the pressure. I don’t know what. But what was a frozen ball of solid space suddenly wasn’t frozen any more. Suddenly it went BANG, and it rang like a bell. Suddenly space was full of vibration and waves and motion as it began to expand. That motion was light, and that light was quite literally turned into matter. Matter that is electrons. And atoms. And molecules. And dust. And planets. And stars. And galaxies. And us.

And here we are.

I know I haven’t given you much, but one thing that comes out in the wash is inflation. The early universe is thought to have expanded extremely fast. But how fast? Forget about that big BANG for a moment. Imagine the early universe expanded at some slow, sedate, steady, pace. Like a pumpkin. If you were in that universe, you would be subject to infinite time dilation. So you would claim that the slow, sedate, steady, pace was infinite. After a while you might be subject to huge but non-infinite time dilation. You would then claim that the slow, sedate, steady, pace was extremely rapid. And whatever you claim, later observers would claim the same. It’s like gravitational time dilation, only there is no gravity. But it’s time dilation in spades, so the expansion looks fast from where you’re standing.

They call it inflation. But for inflation, you don’t need inflatons, all you need is relativity. Then inflation comes for free, and all the rest is easy.

 

12 comments on “Science Sundays with John Duffield: The Big Bang!

  1. Talwin
    November 10, 2013 at 9:29 am #

    I used to read Asimov many years ago, as a teenager, but, until now, never came across ‘The Last Question’

    You are right, religious inclination or no, even the Wiki summary generates a spooky ‘wow!’

  2. duffieldjohn
    November 10, 2013 at 12:39 pm #

    I think it’s one of the best science fiction stories ever, Talwin. It’s the sort of thing that got me interested in physics and cosmology. Here it is:

    http://www.thrivenotes.com/the-last-question/

    I didn’t intend to, but I just read it again. Sniff! It still brings tears to the eyes. Excuse me while I go and blow my nose.

    • Talwin
      November 10, 2013 at 3:13 pm #

      Thank you for that. While I’m at it I’d like to say I read (and re-read!) your stuff every week. Without fail.

      With no maths and only GCE ‘O’ level Gen. Science I (1961) and Astronomy ‘0’ level, some of the concepts are difficult for me to grasp: not trying to be profound, but it’s all a bit dream-like; you think you might just might have it, then it slips through your grasp, and it’s gone. Do you inderstand that?

      But it remains strangely compelling stuff.

  3. Simon Roberts
    November 10, 2013 at 3:34 pm #

    I’ve always felt rather unsatisfied with explanations of the Big Bang.

    I don’t doubt that we can calculate the backwards trajectory of stars to a central point nor that the science of particle physics can theorise what would have been going on when everything was squashed together in whatever form of matter/energy it took at the time.

    It’s just that as we go further back in time, the explanations seem to become more theoretical. That’s perfectly understandable but the whole subject then comes to a standstill when the issue of ‘where did it come?’ from or even ”what came before?’ arises.

    Arguing that time didn’t exist because the way in which we currently measure it (x billion vibrations of a thingy per second) wasn’t applicable is a bit evasive. Same with the concept of distance. It’s not much of a leap of imagination to consider time and distance to be absolutes, regardless of gravitational effects or the inconsistency of measurement.

    Unfortunately, the Big Bang is like Darwinian Evolution in the respect that you are assumed either be a religious fanatic or a believer in science and the whole business degenerates into a choice of the two. I prefer to keep an open mind and accept that there may possibly be explanations that we have yet to discover.

    I’m much more comfortable with the idea that time and space are infinites than with the idea that they have a beginning and end. I’m not buying doughnut-shaped universes either.

    • duffieldjohn
      November 10, 2013 at 4:03 pm #

      I don’t think there ARE any explanations of the Big Bang, Simon. Some people try to pass off “quantum fluctuation” as an explanation, but that’s just another non-explanation that’s right up there with “God did it”. Sorry if I sounded evasive when talking about time not existing if there is no motion. But like I said, I just don’t know how the universe began. I like to keep an open mind too, but I don’t know if we’ll ever know how the universe came about. Maybe it was always there, because you can’t get something from nothing.

      Like you I’m not buying doughnut-shaped universes. But nor am I comfortable with the idea that time and space are infinites. I’m happy enough with expanding universe, and I’m happy enough with the early universe being small. But I just don’t see how it can always have been small and infinite, or how infinite space can possibly expand. I wrote something on this a few weeks back. It’s a bit speculative and a bit of fun, but IMHO well worth thinking about:

      http://bogpaper.com/2013/09/22/science-sundays-with-john-duffield-edge-of-the-universe/

      • Simon Roberts
        November 10, 2013 at 4:41 pm #

        Thanks. I wasn’t suggesting that you were being evasive, I was just musing really.

        On my concept of infinites – I was just trying to say that they are only affected if one considers that their existance is in some way related to the things that occupy them.

        If by “the universe” one means the things that occupy it, then its size is indeed not consistent – what I was referring to is the physical dimensions that they themselves occupy, regardless of what they contain. It doesn’t matter whether the units used to measure the dimensions are affected by conditions.

        I nearly said “space that they occupy” there 🙂

      • duffieldjohn
        November 11, 2013 at 8:11 pm #

        Noted, Simon.

        By the way, the word universe stems from uni as in unicycle and verse like in vice versa. It means “turned into one”, which really means “everything”. So the universe is space and the things in it. Which by the way, seem to be made out of waves in space. Check out the wave nature of matter, and atomic orbitals on wiki where you can read “electrons exist as standing waves”. The electron’s electromagnetic field is basically a standing electromagnetic wave, and you’re made of stuff like that. And get this: when a seismic wave moves through the ground, the ground waves, when an ocean waves moves through sea, the sea waves, and when an electromagnetic wave (or a gravitational wave) moves through space, space waves!

  4. duffieldjohn
    November 10, 2013 at 3:40 pm #

    I do understand that, Talwin. It’s very difficult to make things simple. I’m forever trying to make these subjects easier to understand, and I don’t always get it right.

    But I would say that they aren’t as complicated as people think, and sometimes because people think they’re complicated, they just can’t believe they’re simple. I think time is a great example of that. And when you understand that, you can understand the speed of light, then you can understand gravity. One thing leads to another, but if you drop a stitch somewhere along the way you lose the thread.

    If there’s anything I can try to clarify, please don’t hesitate to let me know.

  5. cementafriend
    November 12, 2013 at 7:58 am #

    John, I am sure I read that many Quasars are closer and moving slower than calculated by red-shifts. I think that was found by the Quasars moving across the face of some stars. I thought the articles implied that the Doppler Red-shift may not apply in certain areas of space.
    I think there is also doubt about the Universality of the Big Bang.
    It is likely that there was some sort of explosion maybe a black hole or a large star the size of a galaxy which commenced a galaxy but I am not convinced that other galaxies were formed by that single “Big Bang”
    I do not go along with everything Tom Van Flandern writes in “Dark Matter, Missing Planets and New Comets” but the evidence he provides for a planet explosion between Mars and Jupiter is convincing.

    • duffieldjohn
      November 14, 2013 at 2:09 pm #

      As far as I know quasars are very distant, and while of heard of some redshift oddities, I’ve never thought it was a big issue. If you can give me a link I’ll take a look. Yes, some people doubt the Big Bang. Others say it was just “a” big bang rather than “the” big bang. Trouble is, there isn’t much to go on. There’s no actual evidence for a multiverses, or a universe like some collection of bubbles. The best information we have suggests that the universe is expanding, and my understanding of relativity and fundamental physics ties in with that, and that’s about as far as I can go. I’m not sure about Tom Van Flandern’s ideas I’m afraid. It’s always good to have ideas, but when they depart too far from what we know it’s a bit offputting. Which maybe sounds ironic coming from me, but I like to think the things I talk about are in line with Einstein and the evidence.

Trackbacks/Pingbacks

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    […] problem there. When you know a bit of physics, the Big Bang is pretty reasonable. And since pair production and annihilation can be done in a lab, what’s not […]

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