Scientists speak of the expansion of the universe. What do they mean exactly by the term universe?-?

Question

We see galactic matter like stars , planets astroids meteors etc in the space. They say that the universe is expanding .For anything to expand , there must be continuity of the matter expanding . Otherwise we say things "scatter" or "drift"or "move away" only. A baloon expands when it bloats . when it is burst , it is not expansion . It is a burst or explosiion.because the matter scatters.Do the scientists include the space also while they say that the universe is expanding ? If so does the space really expand ? Space is emptiness -void -nothing . Can "Nothing " which is not a thing , ever expand?

None of the answers are anywhere near . If theterm Universe is restricted to the galactic mater alone , the right word toapply is that the galaxies are drifitn away from one another ,.it is like the coins arranged in the center of a carom board being struck by a stricker . The coins do not expand ., but scatter. the space among the scattered coins also do not expand .the gap looks to increase because the coins move away. Note that the SPACE is NOTHING. "NO-THING '. Something that is nothing can not expand . It must be a thing to expand . How can anything that does not exist .expand . Just because Scientists apply the term loosely , their assumptions are not universal facts.or truths. They ar huamn and they have proved themselves wrong on many fronts .What any scientist has done , anybody can also do.No man howeve great he might be has ever done anything that anyother huaman can not do. All tahtis rquired is an abiding interest and a will.Think

Answer 1

The expansion of the Universe includes the creation of more space. It is not only the expansion of matter. Void isn't "nothing", Electromagnetic waves can travel through this immaterial media and space can support gravitational or magnetic fields. Void is space, which is something.
So in the expansion, more space is being created. Space has no weight and no energy, so the amount of matter and energy in the Universe remains the same during this expansion.

Added:
I believe your argument is flawed. Space can be finite (and this doesn't mean it has no boundaries). Space doesn't have to be unlimited, and I guess you are thinking only in an infinite space, where only matter determines the size of this Universe. It is the space, and not the matter what determines the size of the Universe. Space was created along with the Big Bang. There was no space before this event, according with this theory and M theory. So space is something, for us it is three dimensions, it is a volume that can expand, and with time they conform our four dimensional Universe. The problem is that we cannot visualize this 4 dimensional expansion living in a 4 dimensional Universe.

Answer 2

There are a few good answers posted already and I won't dispute them, but I thought it might be helpful to offer a layman's example to illustrate the expanding universe.

Think of a balloon. If you put a little air into it, it will form a small sphere.
Now take a marker and draw a couple of dots on it. Measure the distance between those dots.

The surface of the balloon represents space, and the two dots are galaxies in the universe.

Now add more air into the balloon. Think of the air you are putting into the balloon as time. The more time that is in the balloon the more time is in the past, in other words, the balloon is expanding through time.

Now measure the distance between the dots again. They have gotten farther apart! That is because the space (the surface of the balloon) has expanded.

In a nutshell, this is what the universe is doing. It started as a bubble of space-time. As it passed from the past into the future, the amount of time in the past increased and space-time expanded.

Now of course the balloon analogy is just that, an analogy, but I hope that it helps explain things a little better

Answer 3

My best guess, and that's all this is, a guess, is that the Universe is all of Spacetime and everything contained with it. If I had to give a visual example, imagine the Universe is just one of an infinate number of gigantic cd's. Yes. CD's. Like the kind you play music on.

The reason they believe the Universe is expanding is because observably everything within this "cd" is moving "outward. Now unfortunately, only about 10% of the universe is observable. (according to scientific calculations) So we really can't be sure which direction is "outward" and which direction is "inward". But since everything (galaxy-wise) is moving farther apart, it's assumed that the universe is expanding.

In all actuality, the galaxies of this universe could very well just be "migrating" to other areas of the universe, rather than the universe itself expanding.

Answer 4

Universe is a loosely used word. Currently it means the part that we know ( galaxies etc) is called universe. In English dictionary the meaning is different. The space is not expanding. The galaxies are moving apart from one another. You are trying to argue here using the literal meaning of English words as intended to. But English is a very flexible language. Here the words are used not in the literal meaning these words are intended to. So if you understand the physics like balloon expansion etc that is what they mean.

Answer 5

When people discuss the expansion of the observable universe what they mean is simply that large scale systems such as clusters of galaxies are growing further apart and the further they are away, the faster that recession is taking place.

Mathematically the Big Bang Model is based on two assumptions: General Relativity and homogeneity. These assumptions lead to two solutions, one which is infinite and one which is finite. So far the observed data are consistent with both of these solutions although finite solutions smaller than about 150 billion light years are ruled out.

Note to the previous two answerers. Average density is DECREASING, not increasing.

Answer 6

Of course, this universe expands. The scientists say that the space or distance betwen the stars or galaxies keeps on increasing which mean that the universe is also bulging. Expanding universe means that its density is gradually decreasing.

Answer 7

it extremely is mostly a hazard that your concept is misguided, the two because of the fact your unique assumptions are incorrect or your good judgment is misguided or you're lacking some information. that's why theories struggle by using a peer-evaluate. Others seem at your concept and advise fixes (that are themselves peer-reviewed). ultimately, a consensus is reached and which will become the 'ultimate concept to date'. New observations can continually substitute the thought or maybe get rid of that is 'ultimate concept' prestige (seem what handed off to Newton's rules of action). inspite of the undeniable fact that, the longer scientists have had to check the thought and fasten it as mandatory, the greater durable it is going to become to coach that the thought is misguided, the two because of the fact of 'inertia' and since the thought does a outstanding interest at explaining the remark(s). contained in terms of the expansion of the universe, that's at the instant the final concept to date. till we are able to commute out into area far adequate (various million easy years) to validate our assumptions, we are able to be annoying-pressed to coach the assumptions are incorrect. BTW: Supernova are used to degree the cost of expansion, the the life of the expansion itself. additionally, dark count is presumed to exist because of the fact of different observations (ex. galactic rotation velocity). The supernova data mentioned the life of dark potential

Answer 8

In General Relativity, space and time (spacetime) is much more dynamic than the boring static Eulerian coordinate system that is taken for granted and, therefore, thought of as "nothing" in Newtonian mechanics. Spacetime is still describable by a coordinate system quantifying how one gets from A to B in GR, but be careful with words. "Things" in common language are traditionally associated with matter. Things in GR are more inclusive, though. Space can be warped, support waves, form singularities, and, yes, even expand, in GR. It becomes more analogous to a canvas upon which paint (matter) is applied.

As to the original question, the spacetime of [a] "universe" in GR refers to a complete set of contiguous spacetime points, and a metric (or way of measuring displacements) for travelling from one to another. "Contingous" means that, through a any number of incremental steps, one may move (figuratively speaking) from any one point to another in set. Since we're speaking figuratively here, we're not constrained by the speed of light or need to travel forward in time when I say "move". points further apart than the speed of light times the age of the universe are part of the same universe; they're just causally decoupled. "Complete" means that, since you're talking about the universe, the set includes all points that can be so reached. A universe may be infinite or finite. The neatest thing about GR is that in it's noneuclidian space, there are no need for boundaries (walls) for it to be finite. And, oh yes, you generally have matter in a universe.

Answer 9

Really cool question.
I guess what they mean by expansion is an increase in the relative density.

Answer 10

THAT MEANS THE RELATIVE DENSITY OF THE UNIVERSE IS INCREASES GRADUALLY