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Thread: The FORT science outreach project

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    FORT scientist astrogirl_2100's Avatar
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    The FORT science outreach project

    Hi Everyone

    I got a question from AmandaG yesterday about cosmology, and answered it, sparked more questions, and then I thought: why not take the discussion public. I know not everyone is interessted in science, but as a scientist, I feel it is my duty to try.

    My field of expertise is astrophysics, specifically gravity. I work mainly with computer models of black holes, but can also answer question on such exotic topics as wormholes, cosmology and time maschines. I hope other experts in some scientific field will take the opportunity to chime in.

    Anyway, this is AmandaG's original question:

    Quote Originally Posted by AmandaG
    So the universe is roughly 12 billion years old, yes? And distances on an astronomical scale are measured in light years, which is the distance light can travel in a year, right? Okay. So at the time of the Big Bang, energy converted into matter, and the universe was born. In that microsecond, how could the matter have been flung so far and wide? Was it traveling faster than the speed of light at the point of the universe's conception? I understand that now it has had 12 billion years to expand even farther, and I know that it's even speeding up...but that first moment is what I don't get.
    My first answer is:

    Quote Originally Posted by astrogirl_2100
    This is indeed a good question. First, quoting from the mad scientist newwork http://madsci.wustl.edu/
    (lots of good questions and answers there, btw):
    ----------------
    It is a common misconcpetion that space existed, and always has existed, then the Big bang created matter which expanded into space. This may sound strange, but the Big Bang happened eveywhere in space; there is no single point where it happened. To appreciate this idea, you have to understand that the Big Bang created spacetime, afterwhich space began expanding. This leads to the bizarre notion that nothing whatsoever, nada, no space, no matter, no time, nothing existed before the Big Bang.
    -----------------------

    Okay, what does this have to do with your question? You see, since spacetime itself expands, the matter just moves with it. The matter does not move with a speed greater than the speed of light. Imagine a ballon with pennies (or any other coins) attached to it. When you blow up the balloon, the pennies stay in the same place on the balloon. The distance between them get bigger, but the are still attached to the balloon in exactly the same place as before the balloon was blow up. The pennies never move on the balloon. Thus, matter is not flung into an already existing space at speed greater than the speed of light, is is merely expanding along with that space without moving it it.
    The followup question is:

    Quote Originally Posted by AmandaG
    Let's take a point in time a milion years after the Big Bang. From every documentary I've watched and every book I've read (which, admittedly, are directed at laypeople, and, I'm sure, grossly oversimplified), galaxies, stars, what-have-you were forming in their early stages very quickly after the Big Bang occured. At that point, 1 million years post-BB, was the universe vastly smaller than it is today? Is it as simple as calculating 186000 m/s * 1 million years, and generating the size of the universe like that? I suspect it can't be that easy, because you have to factor in expansion rates and relativity, and a bunch of stuff I just don't understand.

    What the hell am I trying to get at here? I'm having the hardest time trying to figure out how to word this. Okay. I understand that before the Big Bang, there was nothing. Time didn't exist before that moment. Some sub-atomic sized bit of energy violently converted into matter. Matter and anti-matter fought it out, matter was in greater numbers and won. Am I right so far? Now, from what I've gathered, all these things took place in a tiny amount of time. Milliseconds, maybe. I could be way off about that, though.

    So those first few seconds, a lot went on, yes? Now, going by your balloon/coin analogy, are you saying that in the early stages of the universe, that balloon was, for all intents and purposes, deflated? Everything was created, but much more proximal than it is today? So if it were possible to build a time machine and find some nice rock to stand on where the Earth woudl someday be, I could look up at the sky of those first moments and see...well, almost everything?
    And I will answer that one in my next post.

    Feel free to ask. If I'm not able to answer maybe someone else is!

  2. #2
    FORT scientist astrogirl_2100's Avatar
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    Okay, so here is my answer to the follow up question

    Quote Originally Posted by AmandaG
    Let's take a point in time a milion years after the Big Bang. From every documentary I've watched and every book I've read (which, admittedly, are directed at laypeople, and, I'm sure, grossly oversimplified), galaxies, stars, what-have-you were forming in their early stages very quickly after the Big Bang occured. At that point, 1 million years post-BB, was the universe vastly smaller than it is today? Is it as simple as calculating 186000 m/s * 1 million years, and generating the size of the universe like that? I suspect it can't be that easy, because you have to factor in expansion rates and relativity, and a bunch of stuff I just don't understand.
    Okay, what you are talking about is the visible universe, which is a different thing that the entire universe. A million years after big bang, you can see a million years back in time (actually less, because the universe was not always transparrent, but bear with me). So you can see a million light-years in each direction. But that does not mean that the universe is 1 million lightyears wide. It just means that the part of the universe that you can see is a million lightyears wide.

    So how come there are parts of the universe we cannot see? Well we know that nothing can move faster than the speed of light. But there is no limit on how much space can expand. In fact, one really active research area is called inflation. To quote John Gribbin, an excellent science writer:

    Inflation is a general term for models of the very early Universe which involve a short period of extremely rapid (exponential) expansion, blowing the size of what is now the observable Universe up from a region far smaller than a proton to about the size of a grapefruit (or even bigger) in a small fraction of a second.

    Think of the balloon with the pennies again. When the balloon is deflated, the pennies are close together. When you inflate is, they move further apart, but they actually didn't move relative to the balloon, they are still stuck is the same place on the balloon. So even though they all have moved further apart, it is because the baloon has expanded, not because they have actually moved. That is the key. Spacetime is allowed to expand as much as it wants. We are not allowed to move faster than the speed of light, but the universe can exapand so rapidly that we're moving away from eachother much, much faster than the speed of light.

    Quote Originally Posted by AmandaG
    What the hell am I trying to get at here? I'm having the hardest time trying to figure out how to word this. Okay. I understand that before the Big Bang, there was nothing. Time didn't exist before that moment. Some sub-atomic sized bit of energy violently converted into matter. Matter and anti-matter fought it out, matter was in greater numbers and won. Am I right so far? Now, from what I've gathered, all these things took place in a tiny amount of time. Milliseconds, maybe. I could be way off about that, though.
    All this is right, you have a good grasp of the basics

    Quote Originally Posted by AmandaG
    So those first few seconds, a lot went on, yes? Now, going by your balloon/coin analogy, are you saying that in the early stages of the universe, that balloon was, for all intents and purposes, deflated? Everything was created, but much more proximal than it is today? So if it were possible to build a time machine and find some nice rock to stand on where the Earth woudl someday be, I could look up at the sky of those first moments and see...well, almost everything?
    Yes, if you just stay right where you are, and do a fast rewind, you will find the universe shrinking. It looks like the whole thing is coming towards you. You will find yourself right in the middle of the big bang, if you rewind far enough. However, if I do the same, I will also be in the middle, and see you moving towards me. Imagine standing on a penny and look at all the other pennies as the balloon deflates. From one penny's point of view, all the other pennies are moving closer to it. But if you pick another penny, that penny also sees all the other pennies moving closer to it.

    Suppose we are very close to the beginning of time. We are close enough to shake hands. But all of a sudden, you're gone! You didn't move, I didn't move, but the universe exapanded in between us. And we will only see eachother again, when we are in eachothers visible universe, i.e. when the universe is old enough so that light will have time to travel from you to me, and vice versa.

    Okay, I'll leave you to mull over than one

  3. #3
    Hypermediocrity Amanda's Avatar
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    First off, thank you so much for your answers, Astrogirl. I don't know if this topic is something that will necessarily appeal to a very broad audience (it's no hottest men thread ), but I'm absolutely fascinated by all of it.

    So let me see if I'm understanding this correctly. Also, again, please bear in mind that I'm going to have to break this down to the most rudimentary terms, as I have zero background in any of it.

    Basically, matter is governed by the laws of physics, i.e. not being able to move faster than the speed of light, but nothingness, by its very nature, can't be subject to those same laws. That's why space can expand in speeds completely unheard of when it comes to matter?

    So, as time (as we know it) goes on, it won't even matter if we build the most amazing, technically advanced telescopes possible, we are limited in how far back we'll be able to see? We'll be moving away from that light from billions of years ago faster than it'll be able to catch up with us?

    If you do figure out how to build a time machine, let me know. I'd like to go back to the early 90's, and major in this in college.

    OH! Here's another question. Wormholes. Those are two connected black holes, right? And they're a theoretical means of time travel, yes? Is the research on them showing that it may be anything more than theoretical someday? It seems impossible to believe that, from a practical sense, anyone would be able to survive that journey.

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    FORT Fanatic VeeJay's Avatar
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    I have nothing to contribute. I just wanted to say I find this extremely fascinating.
    A man can convince anyone he's somebody else, but never himself. - Verbal Kint from the movie The Usual Suspects

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    Staying Afloat speedbump's Avatar
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    Astrogirl, great topic and very interesting. My oldest cousin is a scientist who did her PhD on wormholes and dust clouds( I think?). Anyways, she stole all the science genes from the rest of us, so I'm glad you are so good at explaining things cause when it comes to fathoming space, I'm a big drooling pile of jello.

    My question is somewhat similar to Amanda's. What was in 'space' before the BB? And what force created the 'area' that allowed the BB to expand in? I'm stopping at that because my brain is going to overload.

    p.s. can you use reeeeaaallly simple examples, i.e., baseballs and footballs or pizza and burgers?
    You got to cry without weeping. Talk without speaking. Scream without raising your voice.- U2

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    FORT scientist astrogirl_2100's Avatar
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    Quote Originally Posted by AmandaG
    First off, thank you so much for your answers, Astrogirl. I don't know if this topic is something that will necessarily appeal to a very broad audience (it's no hottest men thread ), but I'm absolutely fascinated by all of it.
    Hey, why not enjoy both (hot men and science). I do

    Quote Originally Posted by AmandaG
    So let me see if I'm understanding this correctly. Also, again, please bear in mind that I'm going to have to break this down to the most rudimentary terms, as I have zero background in any of it.

    Basically, matter is governed by the laws of physics, i.e. not being able to move faster than the speed of light, but nothingness, by its very nature, can't be subject to those same laws. That's why space can expand in speeds completely unheard of when it comes to matter?
    Well, there are laws that govern how spacetime can expand and strech. Just not the same laws and the laws that tell us how we can move around in space. Mostly we observe the universe and then try to figure out how it is behaving. That's where the idea of the accellerating universe comes from, we see that the universe is accellerating, and modify our laws so they can explain the expansion, while they still explain all the other things they did before the modification.

    Quote Originally Posted by AmandaG
    So, as time (as we know it) goes on, it won't even matter if we build the most amazing, technically advanced telescopes possible, we are limited in how far back we'll be able to see? We'll be moving away from that light from billions of years ago faster than it'll be able to catch up with us?
    Yeah, there are parts of the universe we will never see, because the unverse is accellerating. But we well be able to see out to a limit set by the age of the universe.

    Quote Originally Posted by AmandaG
    If you do figure out how to build a time machine, let me know. I'd like to go back to the early 90's, and major in this in college.
    Actually, even if I did invent a time machine, that would not be possible. The laws of physics forbid us to chance anything in the past. I know I'm opening a can of worms with this one, but this actually inhibits out free will. Suppose that some day I build a time machine and decide to go back to this moment and meet myself. From my point of view, an older copy of myself shows up. But this means that my future self is part of my past. And that means, that once I get to the future, I will be forced to go back to the past and meet myself, because the laws of physics forbid me to change anything in the past. The movie that describes this best is "twelve Monkeys". I recommend everyone to see it if you haven't already, it is the best description of time-travel as understood by modern physics.

    Quote Originally Posted by AmandaG
    OH! Here's another question. Wormholes. Those are two connected black holes, right? And they're a theoretical means of time travel, yes? Is the research on them showing that it may be anything more than theoretical someday? It seems impossible to believe that, from a practical sense, anyone would be able to survive that journey.
    Actually, theoretically we know how to make wormholes that last. However, practically we don't. It involves putting a very special type of matter in the middle, when the wormhole is forming. This matter keeps the wormhole open. Without such matter, the hole will naturally close so fast that we cannot get through it. Such matter, btw, does not exist, but it is theoretically possible (not forbidden by the laws of physics). Basically it has positive gravity on the inside (a force that repels things) but from the outside it has normal, negative gravity (i.e. the lump of matter attracts things). The matter holds up the collapse in the middle of the wormhole. We can travel through the wormhole but avoid the matter in the middle. Now we just have to be able to form two black holes that touch exactly at the right moment, generate this special matter and put it inside and then we have a wormhole. Then we can tow one black hole to some far off place, and leave one hole behind, and we'll always be able to go where the tow-spaceship is.

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    FORT scientist astrogirl_2100's Avatar
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    Quote Originally Posted by speedbump
    Astrogirl, great topic and very interesting. My oldest cousin is a scientist who did her PhD on wormholes and dust clouds( I think?). Anyways, she stole all the science genes from the rest of us, so I'm glad you are so good at explaining things cause when it comes to fathoming space, I'm a big drooling pile of jello.

    My question is somewhat similar to Amanda's. What was in 'space' before the BB? And what force created the 'area' that allowed the BB to expand in? I'm stopping at that because my brain is going to overload.

    p.s. can you use reeeeaaallly simple examples, i.e., baseballs and footballs or pizza and burgers?
    Well, the universe does not expand into anything. The universe is everywhere and at the Big Bang, it is created everywhere, all at once. Space is created at the big bang. Thus there is no space to expand into.

    It is better not to try to visualize it the way you are trying to. Visualize what it is like from the inside. If you have a baloon with pennies attached, imagine being a 2D creature who lives on the surface of the baloon (= mr. Flat). Do not imagine the baloon blowing up in 3D, mr. Flat is 2D and he will not see this blowup. Rather mr. Flat will see the other pennies moving away. We see other galaxies move away, which is the same thing in 3D and conclude that the universe is expanding. Maybe streching is a better word. It's not exanding into anything.

    Sorry, that's the best I can do with words.

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    FORT scientist astrogirl_2100's Avatar
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    Okay, I have a question.

    On one episode of CSI, Grissom puts some sort of Fungus on Greg's feet, and they swell up, because Greg is of Scandinavian descent. The criminal is Scandinavian, and has the fungus, leading the the conclusion of the show. Being 100% Scandinavian, I'm curious: what is that fungus, and why would it only attack Scandinavians? Should I be worried?

  9. #9
    Premium Member FinallyHere's Avatar
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    Great stuff. I don't have anything to add other than to say that I'm thoroughly enjoying this thread. Thanks Astrogirl
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    Why Not Us? greenie's Avatar
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    When I first started reading this, I thought I wouldn't understand anything since this topic can be quite complex, but Astrogirl you have a great way of explaining things and I've really enjoyed reading this. And I've liked all of the questions Amanda has posed as well (although it blows my mind the things you ponder ).
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