God’s private room was a nice addition.
Burbinator, I am trying to remeber which article the info on the 44 dementional universe was in - It was a collection of the top 100 people _____ It is the ______ I am trying to remember.
Not only was she brilliant, but not hard ont eh the eyes either.
It’s indeed a very good lecture that even someone with little experience in astronomy/cosmology can understand.
The best part is where he says:
“The amazing thing is that every atom in your body came from a star that exploded, and that the atoms in your left hand are probably from a different star than your right hand. You are all star dust, you couldn’t be here if stars hadn’t exploded. Because all the elements (carbon, nitrogen, oxygen, iron etc.) that matter for evolution weren’t created at the beginning of time, they were created by nuclear fusion in the cores of stars. So forget jesus, the stars died so that you could be here today.”
I wasn’t really trolling, sure the “God’s Private room” was just a joke but the theory about those mirrors have been told earlier on other forums and discussions.
Burb, those are some fascinating links and theories. One thing I didn’t quite follow was that since the universe appears to be flat, it means that it occurred due to quantum stuff. How is that so?
Also, PingWing, that’s beyond dumb. If that were the case, we wouldn’t see galaxies, and it would seem like we were in the centre of the universe.
I’m not exactly sure why or how, but in a flat universe there must be some fundamental symmetry, which means that the sum of all energy is zero. If that is the case, all of that energy can cancel itself out, resulting in nothing, effectively.
I think it has something to do with the new cosmological constant, which is a repulsive force, as opposed to gravity. I’m quite sure the guy explains this a little more clearly somewhere in the lecture, but I can’t remember exactly.
I do remember him saying that a flat universe is the most mathematically beautiful, referring to the symmetry which would cancel itself out, resulting in nothing.
By the way, I think what PingWing might be referring to (although he’s explaining it extremely poorly) is the fact that in a closed universe, you’d end up where you started if you went in one direction for long enough, just like on earth.
The thing that gets me is that if you move perpendicular to the centre of the universe you’d end up on the other side. Something about straight lines not existing, or some craziness.
Soup: You are traveling straight in 3 dimensions (hence a “flat” universe), but you can’t travel straight in the other dimensions; you’ll still be curving.
Think of it like standing on the Earth. You can travel straight along the surface of the Earth and you’ll end up back where you are because you’re curving in three dimensions and going in a very large circle. Same with the Universe. You can travel straight through the Universe and you’ll end up back where you are because you’re curving in four dimensions and going in an insanely large circle.
Oh yeah, I get that, my point was that it’s such an odd concept to think about.
Actually, I don’t think you’d end up back where you come from in a flat universe, but only in a closed universe. In a flat universe the fourth dimension isn’t curved the right way for that, I think.
Or maybe I’m just interpreting those images the wrong way.
I think that is not exactly what would happen. If the universe was close, then its gravity would be so damn big you can’t move perpendicular to its center for too long. It would be like on Earth, you may throw yourself up very fast, but you Earth’s gravity will still pull you back to where you were after long enough. Or, even better comparison, like in a black hole.
Even if you were traveling on a super ship, eventually the fuel of your ship would end and you’d be pulled back. You are not special: if the universe is closed, the entire universe will collapse to its center at some point in time, and so will you.
I think it was pretty obvious that I was talking theoretically. If you’re going to be pedantic, you wouldn’t even be able to reach the ‘edge’ before you died.
Yes, but even if our universe was closed, it would be expanding at the moment. Gravity is not pulling everything to the centre.
And as Soup said, we’re talking theoretically anyway.
I have a simple explanation that explains why the universe is infinite, though not exactly how it all works.
Infinity works both ways, and all ways, really. If any one part of the universe is infinite, than all of it is. For instance:
Focus on an object. How far do you think you can zoom in on it? With your eyes? With a microscope? With an electron microscope? There is always a new technology allowing us to zoom in farther on the things around us, and we keep finding smaller parts to ourselves. We are finding that we can zoom in infinitely.
Therefore, I posit, that if we can look infinitely into our universe’s ever increasing smaller objects, than the universe also expands outwardly at an opposing infinite amount. We will keep finding larger and larger sets of stars, galaxies, universes, and matter beyond. We may not find some giant creature looking in on us like us to quarks (or smaller), but we will find groups of matter is some form of collection that we will not have expected.
Also, time is infinite, therefore so is matter. The universe, and everything in it, is infinite (yes, frogs too).
So was I. I was not being pedantic, I was just trying to explaining what it means that you go back to where you were if you go in a straight line. It doesn’t mean you will appear at the other side of the universe, it means that, if you are thrown at a initial velocity without accelerating later, eventually you’ll get pulled back…
Suppose for a moment that you became a phantom that goes across matter, even the floor below you, but you still have your mass. If your initial velocity is zero, you will be pulled toward the center of the Earth. Since you don’t collide with anything, your velocity will make you keep going, and the gravity will then start slow you down when you pass throw the center. When you are at the other side of the Earth, your velocity is zero and you will start to get pulled back. After the same amount of time, you will find yourself at the initial point.
In the same experiment, If you have a initial velocity (but not too fast) perpendicular to the center of the Earth, your path around the Earth will look like an ellipse (of a circle, if you get the right velocity). After circling through that ellipse, you end up at the exact same point you started. If your initial velocity is pointing up (again, below the escape velocity), Earth’s gravity will pull you back. Finally, if you have a initial velocity pointing at any direction, your path will be either an ellipse or a line segment (which is a degenerated ellipse).
This is what it means for the space to be round shaped. Not that you get “magically” to the other side of the Earth (or universe) if you go up, it means your velocity will diminish slowly and will be pulled back to the same point. After a very very long period of time, billions of years, or more, mind you, but you will.
The only problem is that the Earth is better compared to an open universe, because you can escape if you are fast enough. In a closed universe, you can’t escape, no matter how fast you are, just like in a black hole (since you can’t exceed the light speed).
My point was that, even if you try to accelerate, in a closed universe, you can’t escape. To accelerate, you have to throw something to the other direction. Eventually you won’t have what to throw because the universe is finite. If you magically accelerate you ship without throwing something to the other direction, then you will get to escape from the universe, violating the laws of Physics, but then you are already violating the laws of Physics by accelerating yourself without throwing something back. Therefore this is not a proof that the laws of Physics themselves are wrong, because you would be cheating.
That’s being pedantic. We were talking about what would happen if you tried to travel outside of the universe, not what the difficulties of doing that would be.
I always kinda liked the theory that attempting to travel outside of your universe required the entire amount of energy(included the energy you get by converting all mass into energy) that is already in your universe. The one flaw in that idea is that if that’s the case, then anyone who tried it would have to convert themselves to, if not, then it would be an incredibly arbitrary number “Okay, it takes all the energy EXCEPT for themass of the person escaping the universe, and the machine that accomplishes this. Convenient, isn’t it?”
It depends on what you mean by ‘universe’, really. If you consider the universe as being everything that resulted from our big bang, then the universe isn’t infinite. After all, how can something that is infinite expand?
If you consider the universe as being everything, including other ‘universes’ (in the sense of the former explanation), then it is infinite. This is usually called the multiverse, which is an important distinction to make.
I recommend you watch this.
We experience reality as being four-dimensional. In a three-dimensional sense, the universe is definitely finite, as it’s the state of the universe at one given point in time. In a four-dimensional sense, the universe is infinite, as it will keep expanding forever (according to most current theories).
In a five-dimensional sense, our universe is only one of an infinite number of possible universes that resulted from our big bang. In other words, our universe can be considered a four-dimensional point in the fifth dimension, and so on. In that sense, the universe is infinite.
However, if you consider the state of the universe at this point in time, it is not infinite.
As for the zooming in part, you can’t zoom in on matter infinitely and keep finding smaller particles. At a certain point, all you’ll find is energy. Most of the mass of a proton (which is one of the smallest particles currently confirmed to exist) comes from the empty space between the quarks inside it, anyway, which is the result of quantum fluctuations.
You really have to consider quantum mechanics when thinking about the smallest components of matter.
I don’t think you’re thinking about this the right way. In a closed universe, you never go in a straight line. That’s an illusion which is the result of our limited cognitive capacity.
When you’re moving in what appears to us as a straight line, the energy used to move causes the space you travel through to curve. The energy of the entire universe causes the universe to curve.
You really have to view space not in the way you perceive it, but in a more abstract way.
When a spaceship flies to the Andromeda galaxy in what seems like a straight line, its trajectory is actually curved, because the space it travels through is curved.
That’s why, in a closed universe, you’ll end up back where you started when you go in a ‘straight’ line. Three-dimensional space is simply curved in the fourth dimension in the same way the two-dimensional surface of the earth is curved in the three-dimensional body it lies on.
Again, you’re still viewing this the wrong way. Velocity has nothing to do with it. You can go as fast as you like (within the bounds of physical laws, of course), without being slowed down by gravity, unless you’re going away from some body of mass.
Your analogy is flawed, as there is no central point of gravity in the universe. And in this quote you would be outside of the universe, according to your analogy.
You can’t escape the universe, whether it’s open or closed. There are no boundaries to cross. Theoretically, you could go to another universe, but that requires you to travel in the fifth dimension.
The earth is certainly not better compared to an open universe. When you’re comparing the earth to a closed universe, you should only consider the earth’s surface, and nothing else.
By this logic, something moving by simple inertia alone could ‘escape’ the universe, as such an object is not ‘throwing something back’.
No, you can never escape the universe, except by travelling in the fifth dimension to another universe.
When you’re bound to the third or even fourth dimension, it is impossible to ‘escape’, ever, in any sort of universe.
I hope I’ve made a few things clearer to you. And feel free to point out any flaws in my arguments.
Edit: Actually, I’m going to review some of the properties of an open and a flat universe, as I’m not sure anymore how to imagine it in terms of ‘boundaries’.
The way I’m visualising the whole “not being able to leave the Universe thing” is kind of like a magnetic field.
I’m thinking of those lines as a possible trajectories, though obviously not the middle one since that’s only hypothetically straight. They start off as straight but since space curves no matter the trajectory they’ll always end up back in the universe.