Brain Makeover #11: The Universe.

The universe was born at a specific time in the past, and it has been expanding ever since.

The American astronomer Edwin Hubble discovered two important facts about the universe.  First, he showed that matter is clumped together into large collections of stars called galaxies, and, second, he showed that galaxies are moving apart from each other. If you think of “running the film backward,” you see that the Hubble expansion implies that the universe began at a specific time in the past—a little more than 14 billion years ago, in fact. The idea that the universe began in a hot, dense state and has been expanding and cooling ever since is the main tenet of the Big Bang picture of the universe.

We now know that  visible matter is actually only a small part of what the universe contains. Over 90% of the mass of a galaxy is made of dark matter. We do not yet know what it is, but we can see its gravitational effect of stars. Furthermore, we now know that the expansion of the universe is accelerating rather than slowing down. This means that there is another kind of material in the universe, dubbed dark energy, that is capable of exerting a force that overcomes the attraction of gravity. Understanding dark matter and dark energy are the primary goals of cosmology.

Today, scientists can trace the history of the universe back to within a tiny fraction of a second of the beginning, both through experiment and theory. Understanding the beginning of the universe is another goal of cosmology.

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  • Alan Cordeiro

    I have an idea about how this might be possible. If every particle and every charge in the universe has an equal and opposite particle or charge somewhere else to balance it out, then the net total of the universe is still zero, the same as prior to the Big Bang. The Big Bang separated opposite charges on a very large scale, probably with each pair splitting in opposite directions. Think of how a sine wave is zero at the origin, then has a positive peak in one direction and a negative peak in the opposite direction.

    Most of the visible universe is matter, not antimatter. Perhaps the explanation for this is that the antimatter went into other dimensions that are not visible to us. In any event, I suspect that it all balances out in the end.

  • Alan Cordeiro

    I have an idea about how this might be possible. If every particle and every charge in the universe has an equal and opposite particle or charge somewhere else to balance it out, then the net total of the universe is still zero, the same as prior to the Big Bang. The Big Bang separated opposite charges on a very large scale, probably with each pair splitting in opposite directions. Think of how a sine wave is zero at the origin, then has a positive peak in one direction and a negative peak in the opposite direction.

    Most of the visible universe is matter, not antimatter. Perhaps the explanation for this is that the antimatter went into other dimensions that are not visible to us. In any event, I suspect that it all balances out in the end.

  • Einar coutin

    How come hypothesis on Theoric Physics do not require actual experiments. They just require an interpretation of what we are limited to observe from this distant point and then a bunch of brain power, and sweat goes into mathematics to validate that. C p.annf erby- i.y cyv (Bry. naoy lapy. ,pcyy.b cb Ekrpat)

  • Einar coutin

    How come hypothesis on Theoric Physics do not require actual experiments. They just require an interpretation of what we are limited to observe from this distant point and then a bunch of brain power, and sweat goes into mathematics to validate that. C p.annf erby- i.y cyv (Bry. naoy lapy. ,pcyy.b cb Ekrpat)

  • I’m against Universe expansion:

    For example a question: – The universe expand in any radius at light speed: How can accelerate? At what speed expand the diameter (radius x 2)?

    also: – If near universe is the future of far universe and with many times more separation: How is it possible that near are many more stars and galaxies?

    This and more, also doubts, proofs and hypothesis in http://bigbangno.wordpress.com

    Thanks.

  • I’m against Universe expansion:

    For example a question: – The universe expand in any radius at light speed: How can accelerate? At what speed expand the diameter (radius x 2)?

    also: – If near universe is the future of far universe and with many times more separation: How is it possible that near are many more stars and galaxies?

    This and more, also doubts, proofs and hypothesis in http://bigbangno.wordpress.com

    Thanks.

  • That was actually published by Victor Stenger, among others, in a scientific paper (Philo 9, no. 2 (2006): 93-102). Another interesting observation is that the total energy content of the universe is zero (because potential and kinetic energy cancel out).

  • Because that's not their job–the experimental physicists are the ones that validate these hypotheses. Theoretical physicists put hypotheses forward and the experimentalists test them.

  • Presumably, your first question is asking how the universe can accelerate when it's already going at light speed. Well, it always has been going at superluminal (faster than light) speeds since the origin. Although special relativity prevents any subluminal particle from reaching luminal or superluminal speeds, general relativity (which applies wherever there is acceleration) shows that there is no speed limit for spacetime. It's not the galaxies that are flying apart; rather, it's the space between the galaxies that are expanding.

    “At what speed expand the diameter?”–what? Are you asking at what speed the diameter is changing? We don't even know the diameter of the universe (because it's greater than 13.7 Gly), and besides: it's impossible to determine absolute motion; only relative motions can be detected.

    I don't get what you're asking in the third question at all. Can you elaborate a little more on that?

    Also, I looked at that blog you linked to, and most of it was either a misunderstanding of the theory, or a deliberate straw-man. If that's your best shot at falsifying the Big Bang theory, I'm disappointed.

  • Our whole universe was in a hot, dense state
    Then nearly 14 billion years ago expansion started–wait…

    The Earth began to cool,
    the autotrophs began to drool,
    Neanderthals developed tools,
    We built a wall (we built the pyramids).
    Math, science, history,
    unraveling the mystery
    that all started with the Big Bang (bang)!

    Also, there is no evidence that the Big Bang was actually the beginning of the universe; it (or, rather, one Planck time after the Big Bang) is just the earliest point we can observe. The jury is not in, however, on whether or not the universe actually began with the big bang; and anyone who tells you otherwise is either misinformed or lying to you.

  • Our whole universe was in a hot, dense state
    Then nearly 14 billion years ago expansion started–wait…

    The Earth began to cool,
    the autotrophs began to drool,
    Neanderthals developed tools,
    We built a wall (we built the pyramids).
    Math, science, history,
    unraveling the mystery
    that all started with the Big Bang (bang)!

    Also, there is no evidence that the Big Bang was actually the beginning of the universe; it (or, rather, one Planck time after the Big Bang) is just the earliest point we can observe. The jury is not in, however, on whether or not the universe actually began with the big bang; and anyone who tells you otherwise is either misinformed or lying to you.