Did the expansion rate of the universe exceed lightspeed?

maybe i was looking at it crooked, but i assure you my algebra and calculus arent too shabby, although i know it isnt saying much but i do have the transcripts to prove iti was for some reason thinking about it as, some fraction of your speed in relation to light speed and the time change you experience having to add to one. i suppose it is a good thing i made such a stupid error tho, because now i actually understand how to look at it.Edited by LouieP, : No reason given.Edited by LouieP, : No reason given.

Cavediver, If I pick up a stone and take it to the end of the universe, and drop it, and there's nothing except the earth, how fast is it going when it hits the ground?

E=mc²/(1-u²/c²)^1/2Is discontinuous at u = c. And to suggest u > c IS imaginary. Edited by LucyTheApe, : Try Html

Hello LucyThe Ape: If I may field an easy one:In a static universe 11.2 km/s. But that also pretty much ” (10.9 km/s),neglecting atmosphere ” applies to a stone dropped from 300 km up.Edit: I had originally calculated the greatest distance at which one could drop a stone from in our dynamic universe and still have it fall at all and botched the reasoning; hence, a wrong answer. I'll sleep on it.Edited by lyx2no, : I screwed up an easy one.Edited by lyx2no, : I was too sloppy in my "round about".

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Kindly******Fractally impudent

I would think of the 'universe' as the skin of a balloon, where it suddenly was 'inflated' Each point on the balloon doesn't really move, but is 'futher' away from each and ever other 'point' on the balloon.

If there were only the earth in the Universe, your Universe would be infinite in extent, and described by the Schwarzschild geometry (with a slight Kerr-Newman perturbation). In this case, lyx2no is correct - the stone would be travelling at around 11.2 km/s when it hit, assuming it was released from some sufficently large distance away, and ignoring air resistance. It is independent of exactly how far away it is dropped, and as space is infinte in this case, you can go as far away as you like.In an expanding Universe, a stone sufficiently far away will never make it to the Earth as the expansion will work to increase the distance between the stone and the Earth.

Good morning cavediver: Sufficiently far by this mornings calculations is 14 parsecs.I also cleaned up my statement for a static drop as well. I’ve got to remember that no matter how insignificant an error, even if not relevant to an argument, will be pounced upon by those desperate to defend an untenable position.Edit #2: Last night when doing the original calculations I used an erroneous conversion factor of 3.09”10²⁵ m/Mps and failed to notice that it was three orders of magnitude high when I picked it back up this morning.The correct figure should be 0.43 parsecs, maybe.Edited by lyx2no, : TypoEdited by lyx2no, : To pull my head out.

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Kindly******Fractally impudent

Hi cavediver,I have another one of those questions I don't want to be a stupid question so I will ask it.The explanation for the rock falling and the expansion of space between earth and stone dropped trigered my question.If expansion as has been explained to me several times is true.
Everything is fixed with nothing moving only space expanding between those fixed objectsCould you explain to me how that two of those objects that are 2.5 billion light years apart at present could end up in the same place?God Bless,

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"John 5:39 (KJS) Search the scriptures; for in them ye think ye have eternal life: and they are they which testify of me."

For the umpteenth time, nobody said nothing is moving. It's just that local motions are very tiny when compared to the expansion of space when measured between distant points.Let's go back to the balloon analogy. The expanding 3-dimensional universe is analogous to the 2-dimensional surface of an expanding balloon as it is being inflated. Imagine that it's a really, really big balloon and that we can inflate it infinitely. On the surface of this balloon are tiny, tiny mites walking around. The mites are living, and so the blood within them is also moving around. So not only is the blood moving around within the mites, the mites are moving around on the surface of the balloon, and the balloon is expanding.Two mites that are close together will easily be able to approach each other, because there's only a little bit of balloon material separating them, and they can move faster than the balloon is expanding.But two mites that are far apart on the balloon might have trouble approaching each other if the distance is great enough, because the more balloon material separating them the faster they move apart because of the expansion of the balloon. Two mites sufficiently far apart would be receding faster than the maximum speed at which they can move and would never be able to make contact.Note that the speed with which distant mites are receding from each other has little to do with the speed or direction at which they are walking, because the expansion speed is so much greater than their own.The blood moving around within the mites is analogous to the stars moving around inside galaxies, and the mites moving around on the surface of the balloon are analogous to galaxies moving around within the universe. Just as the mites are slowly moving around on the surface of the balloon, the galaxies are slowly moving around within the universe. And just as the mites motion is tiny compared with the expansion of the balloon when measured across distant parts of the balloon, the galaxies' local motion is dwarfed by the expansion of the intervening space between distant galaxies and isn't a significant factor, which is why it usually isn't mentioned.--Percy

Thanks Percy, I understand that in our Milky way stars, planets, moon, sun, and other stuff moves around in our galaxey.Sorry Percy, I will try to be clearer in my thoughts in the future.Now am I to understand our entire galaxey moves around, or is it stationary with space expanding between it and all the other galaxies?I understand that we have a star that is saying good-by to our galaxey as it is streaking toward escape from our Galaxey at well past excape velocity.God Bless,

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"John 5:39 (KJS) Search the scriptures; for in them ye think ye have eternal life: and they are they which testify of me."

In the balloon analogy, the mites walking around on the surface of the balloon were analogous to the galaxies moving around within the universe, so yes, of course, our galaxy is moving. And so is the nearby Andromeda galaxy. The Andromeda and Milky Way galaxies are on a collision course with an estimated time of impact about 2.5 billion years from now.--Percy

Thanks Percy, But that raises more questions.Since they are 2.5 billion light years apart and are expeced to collide in 2.5 billion years. That means that they are traveling at light speed toward each other.If expansion is true and expansion it taking place at light speed and is accelerating, they would never be able to collide.If there is zero expansion and they are traveling at light speed toward collision that can happen in 2.5 billion years.Or am I missing something there?God Bless,

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"John 5:39 (KJS) Search the scriptures; for in them ye think ye have eternal life: and they are they which testify of me."

You're off by a factor of a thousand - the Andromeda galaxy is only about 2.5 million, not billion, light years away. The two galaxies are approaching each other at about 1/1000 the velocity of light.The Andromeda and Milky Way galaxies are so close together that the expansion of space between them is not significant in comparison to their local motions, plus they are gravitationally bound to each other, meaning that the expansion of space in such close quarters is too small too pull them apart. Galaxies must be separated by much, much greater distances before the expansion of space becomes a significant contributor to their apparent relative motion.For a simple visualization of what our local region of the universe looks like with respect to galaxies, imagine you're in room with DVD disks floating around at random that are separated by an average of about six feet. They're moving very slowly relative to the size of the space they occupy, as it will take the two DVD's that represent the Andromeda and Milky Way galaxies about 2.5 billion years to close the intervening 6 feet.--Percy

There are no objects 2.5 billion ly apart that will end up at the same point (neglecting re-collapse) - you are thinking of M31, the Andromeda galaxy, and The Milky Way. These are a mere 2.2 million ly apart - practically on top of each other from a large scale structure point-of-view. And a collison in 2.5 billion years means that they are moving at a small fraction of c with respect to each other.Neighbouring galaxies (such as ours and M31) are largely unaffected by the expansion of the Universe, becasue local gravity dominates. The expansion visibily operates on the scale of clusters and super-clusters of galaxies.

You're also perpetuating this little myth, in addition to the rather glaring mathematical mistake Percy and Cavediver pointed out.If the Unvierse were "expanding at light speed," you'd never be able to read this message - the space between your eyes and the monitor would increase at the same speed the light travels, so the light would never reach you.The expansion of the Universe can't really be described as a "speed." There is a rate to the expansion, but as I recall it's expressed in (Distance/time/parsec). That means the farther away an object is, the faster it will be moving away from you. Close-together objects will barely be moving apart at all relative to each other - the expansion is insignificant at scales like the distance between you and your monitor, the distance between the Earth and the Sun, and even the distance between the Milky Way and Andromeda galaxies. As cavediver explained, the expansion is only significant at extreme distances, a the scale of galactic clusters.Basically, the expansion of space is occurring for all units of distance, so the rate of expansion is additive. The rate of expansion for objects two feet apart is twice the rate of expansion between objects one foot apart. The rate of expansion between you and your computer monitor is imperceptibly small. The rate of expansion between you and an object 100 billion (not million) lightyears away would be relatively "fast."Think of the balloon analogy again. All of the surface area on the balloon is expanding at the same rate. The distance between two mites an inch apart will be increasing slowly. The distance between two mites 6 inches apart on the balloon will be increasing 6 times "faster," even though they aren't actually moving at all. They can also have their own real motion in addition, but the expansion of space is not real motion with inertia or anything else we're used to.Cavediver explained all of this at the start of the thread. Stop repeating the smae misconception 5 pages later, please.