Expanding universe Definition and 229 Threads

Hey guys, I've been wondering a lot about this Big Bang Theory, as I think it is terribly constructed. Anyways, I realize that cosmologists have observed that the universe is expanding and even accelerating in it's expansion. However, I don't see how this can be possible with the laws of...

Let us say we have a universe permeated with a monochromatic photon gas of wavelength L0 at time t0 and the universe is expanding (say for simplicity with a constant rate H, Hubble's Constant). If I sit there and measure the wavelength of the photons as a function of time, what does it look...

The mathematics passes me by, so please be patient. I have an idea that may have been posited before, but I've not seen it. Could it be that the expansion of the universe as we see it is only a relatively minescule fraction of the whole expansion? I have a mental image of the gaseous...

I recently read in my "10th grade" physics textbook that the universes is constantly streaching making solarsystems farther apart, yet for some weird reason all objects still stay intact. This explination included ireverence for such fundimental concepts as the cartisian coordinate system. I...

Try thinking about measuring the expansion of the universe based on relativity. That is to say that depending on where you are located in the universe you might measure expansion or you might measure contraction! Think about this. The observer is placed anywhere inside of a giant ball of...

I have a question about the light observed from galaxies that are moving away from us due to the expansion of the universe. I understand that we can tell they are moving away because the light from these galaxies is red shifted. I was wondering how this red shift is generated, exactly. Is the...

Hello everyone. I'm a beginner with questions :rolleyes: Can someone tell me what happens with black holes in an expanding universe? If the fabric of the universe is expanding wouldn't this result into weaker interactions inside the black hole up to the point when the black hole cannot hold...

It is accepted that the universe is expanding yes? and it is also expanding at a slower rate than the speed of light. therefore what happens when light hits "the edge of the universe"? where does this energy go? and i know that the universe is "everything" but if the universe is 'expanding' then...

In another thread 'Entropy, information and Omphalos cosmology' I commented on a strange fact (which I think many are aware of): namely that to which there was an interesting reply: This subject seems to me not to have an immediate bearing on questions of entropy (or Omphalos cosmology...

If the universe is isotropic and the gravitational properties, which we observe in small objects such as planets, stars and even neutron stars and black holes, apply to large objects such as galaxies and even the universe as a whole. Can we then assume that as the universe is expanding it is...

Hi! Do you know how theories in Metaphysics explain the expanding and accelerating universe? Intuitively i think of expanding consciousness but then what is consciousness? The "thing" that i observe my own thoughts with? :smile:

the universe is expanding. The space between particles of an object is also expanding. So will the force of expanding eventually break the attractive force between particles? stupid question.. help me please anyway thanks

This thread is an offshoot of https://www.physicsforums.com/showthread.php?t=83978&page=1&pp=20. Hmmmm, OK... ex·pand v. intr. 1. To become greater in size, volume, quantity, or scope: Air expands when heated. This critic's influence is expanding. 2. To speak or write at length or...

I am quite confused... I'll state that up front to make it simple. ^_^ Here is my question, though: Assuming that the universe at some point started from a singularity, err... or even that, assuming that the universe is expanding at a rate that has varied over time... I assume that it's...

I'm trying hard to find a decent explanation for someone that an expanding universe doesn't mean that galaxies get stretched out and made bigger; that the planets won't get further away from the sun; that we don't grow bigger etc. I've googled and searched about but a decent explanation of...

When Big Bang occurred everything was thrown in different directions at high speeds. Is this speed constant or are the speed at which galaxies travel slowing down? Since the general theory seems to be that Big Bang is a neverending procedure, galaxies should be slowed down by the gravity of...

Before asking a qusetion let me put first the statement of big bang cosmolgy: "These are not galaxies which are going away from us in a fixed space, this is the space between galaxies which is opening up or stretching." Now my question is: In both the cases (either space stretch or galaxies...

First let me thank you for allowing me to attend your forum. Two queries actually, but I'll begin with this one. Once again I saw a graphic depiction of the expanding universe in a news article. The usual one of course, the expanding balloon with the galaxies tattooed upon it's surface. One...

Please excuse the simplistic approach to the following question. If one accepts that the universe is indeed expanding could this not be simply because the relative strength of gravity has or is diminishing? Instead of suggestions of dark energy and or dark matter to make equations make...

WMAP has conclusively proven an expanding universe. anyone care argue?

hi every one. i was on my way out of my astronomy class today and i hit my self with an odd question. The universe is expanding and as a result it is cooling, now i was wondering if the universe expands infinitly then would it be possible for it to cool infinitly as well. eventualy reaching...

If the universe were divided into two mass zones, and one zone repelled the other,supernovae would not only accelerate away from us but the zone in which we are living would accelerate away from the supernovae.Also cosmic rays could be repelled by one zone and pushed through another.Could...

Hello all, I am from Amsterdam, the Netherlands. I am an super-amature on this topic but I have a question. Is it not possible that the universe is expanding because the amount of matter is growing? See it like a bucket filled with water(universe), throw a rock(matter) in the bucket and...

There is some discussion about the expansion "of space" in a thread that actually belongs to a different topic so I thought I'd start a thread about that with my input here. Consider the Robertson Walker metric in the following form ds^2 = dct^2 - \frac{R^2}{R_{0}^2}\frac{d\rho ^2 + \rho^2...

Help me please! do'nt know if I'm right here, but any hint leading to a simple answer of the following question would be appreciated: if the universe is expanding, are we expanding as well? does my hand expand at the moment? what about a center of expansion? what about our point of...

Help me please! do'nt know if I'm right here, but any hint leading to a simple answer of the following question would be appreciated: if the universe is expanding, are we expanding as well? does my hand expand at the moment? what about a center of expansion? what about our point of...

Hi, I have read a bit about open, closed, and flat universes, Hubbles Constant, the accellerating universe, big bag, big cruch, etc... Is it possible that the expansion rate (+ or -) of the universe might be independant of the expansion rate (+ or -) of the matter within it? Is it...

We are told that as the Universe expands, the 'temp' of it cools and we now have the microwave background radiation as a remnant. Fine. Considering the energy density of the universe, energy is indeed conserved as it expands and cools. However, what about an individual photon, who's...

How is it that we are able to see galaxies that are billions of light years away considering that we are presumably traveling from the same origin? Would that somehow mean that the distance between the two galaxies was growing at a rate greater than the speed of light? If not, why not? The...