Now astronomers have pushed the Hubble Space Telescope to its limits by finding what they believe is the most distant object ever seen in the universe. Its light traveled 13.2 billion years to reach Hubble. The dim object is a compact galaxy of blue stars that existed 480 million years after the Big Bang, only four percent of the universe's current age.
Maybe my pee brain just can't grasp all this but theres something I haven't been able to understand about this "age of the universe" stuff.
It says it's light traveled 13.2 billion years to reach Hubble, If the object was there 13.2 billion years ago and the universe started from one single spot with the big bang and since nothing can travel faster than light wouldn't that make the universe at least 26.4 billion years old?
Maybe my pee brain just can't grasp all this but theres something I haven't been able to understand about this "age of the universe" stuff.
It says it's light traveled 13.2 billion years to reach Hubble, If the object was there 13.2 billion years ago and the universe started from one single spot with the big bang and since nothing can travel faster than light wouldn't that make the universe at least 26.4 billion years old?
I'm no physicist either and general relativity makes my head hurt almost as much as quantum physics does.
Just like the galaxies painted on to the surface of this balloon aren't moving but are getting farther apart, because the balloon is expanding, the real galaxies in the Universe are getting farther and farther away from one another (and, therefore, from us), but due to the expansion of spacetime
But the stuff that's 46.6 billion light years away now was much closer in the past, and the total distance that light has traveled to reach us is 13.7 billion light years; it's just that the Universe has kept on expanding throughout that light's journey.
That's why the light gets redshifted; that's why the galaxies look like they're moving away from us. But what we're seeing is actually the expansion of the Universe, and the expansion continues before the light was emitted, during its travels to us, and after we've received it; and that's how the observable Universe can be 93 billion light years across, even though it's only 13.7 billion years old!
The universe didn't start with one single spot, it was just more and more dense the earlier and earlier you go. A singularity is a mathematical artifact that tells you your theory isn't up to the task of describing your phenomenon.
And nothing can accelerate to and past the speed of light, but things "move" faster than light all the time, depending on your definition of what "move" is. To move, you need a set of coordinates, and that's something that is very different in GR than it is to our normal idea of Cartesian coordinates. See Comoving coordinates.
There are galaxies that are receding away from us at faster than the speed of light right now, but they aren't moving through space faster than light in their own frame of reference. Space is expanding so the galaxy is being carried away from us faster than light.
Think of it this way. Shine one flashlight in one direction, and another in another. To you, the distance between the "front" of the beams of light is increasing at 2 times the speed of light, and that's ok.
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Just like the galaxies painted on to the surface of this balloon aren't moving but are getting farther apart, because the balloon is expanding, the real galaxies in the Universe are getting farther and farther away from one another (and, therefore, from us), but due to the expansion of spacetime
But the stuff that's 46.6 billion light years away now was much closer in the past, and the total distance that light has traveled to reach us is 13.7 billion light years; it's just that the Universe has kept on expanding throughout that light's journey.
That's why the light gets redshifted; that's why the galaxies look like they're moving away from us. But what we're seeing is actually the expansion of the Universe, and the expansion continues before the light was emitted, during its travels to us, and after we've received it; and that's how the observable Universe can be 93 billion light years across, even though it's only 13.7 billion years old!
funny thing is this doesn't answer T@T's question at all. I read a lot about physics and still can't quite grasp how lightspeed effects the actual shape of the universe. below is a picture of the universe from hubble showing the thermodynamic state of matter, except that it's coming from different sources from different distances so this isn't really what things look like, and that's what T@T was asking or hinting at.
funny thing is this doesn't answer T@T's question at all. I read a lot about physics and still can't quite grasp how lightspeed effects the actual shape of the universe. below is a picture of the universe from hubble showing the thermodynamic state of matter, except that it's coming from different sources from different distances so this isn't really what things look like, and that's what T@T was asking or hinting at.
Oh the confusion
From what I gather so far they are saying that the visible universe (light from galaxies) can only travel at light speed, but the dark/invisible space expanding these galaxies is much faster...kind of my layman's way of understanding it anyway.
BTW I don't think thats from Hubble, can't remember what took that snapshot but it was some kind of background radiation probe from nasa.
Ok, I have another question (last one today I promise)
If in-fact this video explains expansion(balloon theory) how is it that galaxies collide? It happens all the time, Even our own milky way is suppose to collide with the Andromeda galaxy in a about 3 billion years.
Ok, I have another question (last one today I promise)
If in-fact this video explains expansion(balloon theory) how is it that galaxies collide? It happens all the time, Even our own milky way is suppose to collide with the Andromeda galaxy in a about 3 billion years.
You could also ask why do solar systems stay together. The expansion is quite weak and is only significant over very long distances.. the distances between galactic clusters and greater. At "smaller" distances (like the distances between galaxies in galaxy clusters) gravity is stronger, so gravity dominates. Andromeda is moving towards us because gravity dominates at that scale.
Same thing for our solar system, the expansion is so weak at that scale the gravity of the sun dominates, or the electromagnetic, weak, and strong forces dominate at the size of our bodies.
Quote:
Originally Posted by robocop
funny thing is this doesn't answer T@T's question at all. I read a lot about physics and still can't quite grasp how lightspeed effects the actual shape of the universe.
The "shape" of the universe isn't dictated by light speed, it's dictated by the mass in the universe and the nature of gravity. What you're looking for is called the Friedmann–Lemaître–Robertson–Walker metric, which is the current best guess about the geometry and topology of the universe.. infinite and flat best guess, though I think there's some other weird multi-dimensional shapes that could fit too.
Quote:
Originally Posted by robocop
below is a picture of the universe from hubble showing the thermodynamic state of matter, except that it's coming from different sources from different distances so this isn't really what things look like, and that's what T@T was asking or hinting at.
That's the Cosmic Microwave Background Radiation, basically a picture of the radiation when the universe became transparent as it cooled (called the surface of last scattering). This radiation has been redshifted so much as the universe expanded that it's now at a colour temperature of 2.725 Kelvin, and it'll continue to drop. What that picture shows is the variation in temperature (a variation of only micro Kelvin) of that radiation, which is due to the variations in density of the material of the universe when it became transparent.
The thing with distance is it's not a simple definition due to the expanding universe, the limit of light speed, and time being relative, so any answer given (like that the universe is 46.5 billion light years in radius) is given with certain assumptions (like that distance is in comoving coordinates).
Plus we can only talk about the observable universe, that what we can ever possibly see.. the actual universe is probably far bigger, and likely infinite.
You could also ask why do solar systems stay together. The expansion is quite weak and is only significant over very long distances.. the distances between galactic clusters and greater. At "smaller" distances (like the distances between galaxies in galaxy clusters) gravity is stronger, so gravity dominates. Andromeda is moving towards us because gravity dominates at that scale.
Same thing for our solar system, the expansion is so weak at that scale the gravity of the sun dominates, or the electromagnetic, weak, and strong forces dominate at the size of our bodies.
I do understand the power of gravity and even the possibilty that it can force matter to go faster than the speed of light (black holes)
But that balloon theory doesn't really do it for me as they left out gravity and the effects it has on galaxies.
I think a theory that gravity and massive black holes are pulling galaxies apart is better than the total unexplained balloon theory.
I do understand the power of gravity and even the possibilty that it can force matter to go faster than the speed of light (black holes)
But that balloon theory doesn't really do it for me as they left out gravity and the effects it has on galaxies.
I think a theory that gravity and massive black holes are pulling galaxies apart is better than the total unexplained balloon theory.
black holes trap light because of the wave-particle duality nature of the photon as it travels by the event horizon, they don't cause light or mass to accelerate past the speed of light, they can create a lensing effect though.
My the point was that people take the image of the night sky as an image of what the universe looks like while the significance of relativity on simultaneity dictates that the universe has to be very different than we perceive it to be, then again can you really define something as having happened before the gravity waves reach an observation point? yeah I know that was the background radiation, i didn't mean to post that image.
and light-speed helps dictate the shape of the universe because gravity waves travel at c and thus a change in mass through antimatter interactions can only effect a certain point in space once the gravity reaches an observable point.
Really makes you feel tiny & insignificant doesn't it...
