Where Does Space End? It Must End Somewhere!

[Severian]

I don't follow..

 

Well, I find it very discouraging the way people discuss these topics. They start with a statement "The universe has property A" where 'A' is some arbitrary guess or preconception of what they think the universe is like. Then many people explain to them why the universe is not like A at all. They argue for a while, but incontravertable evidence is produced to explain why we say it is not like A. They pipe down and discuss some other sidepoint, and then a few days later say "The universe has property A" again, and the whole process starts all over again. (Usually they make a new thread, but in this case they didn't even do that...).

 

Its a bit soul destroying really,

[Sayonara]

The cure is simple:

 

1) Member posts incontrovertible proof,

2) Some degree of co-ordination occurs,

3) Thread closes,

3a) Subsequent threads redirected to closed original with helpful "look here, smiley" message, then closed themselves,

4) Souls saved - PROFIT!

[Severian]

So why is this thread still open then?

[Sayonara]

Dunno.

 

Space tigers did it?

[Martin]

Hi Sev, hi Sayonara,

 

I suppose one alternative to locking thread in disgust is TRYING TO MAKE IT NICE again.

 

It has been a long thread. Here is Sev's post #40 from 2004!

 

Sorry, but I disagree with this. Space is infinite, in the sense that most people mean: if you set out in one direction you can travel forever without ever hitting a boundary. There is no 'void' - space just keeps on and on. I don't see why you have a probelm with the conservation of energy here, and I am a little unsure of what you mean by the universe's 'maximum'?

 

At the moment of the big bang, space-time was 'created', and it was then already infinte (created is not really an adequete word since 'created' really implies time existing before, which it didn't - we have argued this many times with the philosophy nuts who visit here from time to time). All it is doing is stretching outwards. If there was enough mass to close the universe (which there is not), the gravitational attraction of the mass in the universe would eventually overcome the initial impetous of the big bang and the universe would start to collapse. At the 'big crunch', the universe would still be spacially infinite (or have periodic boundary conditions). In actuallity, there is not enough mass to do this (according to the WMAP data) so it will keep expanding forever, and the universe will undergo a heat death.

 

Notice that whether or not space is infinite is not the same as whether or not there is infinite mass in the universe. The latter has been proven to be false, but the former has not. It doesn't really make sense to have a boundary though, since that would imply a 'centre' to the universe, breaking translational symmetry.

 

When we look at the night sky, the universe that astronomers see is finite but in a different sense. Since the light which we see has to take time to get to us, and the universe is about 14 billion years old, the furthest we can possibly see is 14 billion light years (actually it is less than that, but these are details...). So in this sense the universe is finite, but I think that is a little misleading.

http://www.scienceforums.net/forum/showpost.php?p=94449&postcount=40

 

Severian, is there anything you would want to change, or clarify, three years later?

You referred to the WMAP data, at that time only the WMAP first year results were available, but in 2006 we got WMAP3--the three-year data.

People had been waiting impatiently, it changed the picture somewhat.

 

there has also been new supernova studies and new GRB, and galaxy survey data. Ned Wright put all four or five independent data sets together in a recent paper (February 2007 IIRC) and drew fresh conclusions.

 

All this stuff has relevance to the issues raised and discussed in this thread.

 

So, if you want, since it is an active popular thread, we could try to keep it open and raise the level----put it more on the basis of what can you conclude from the latest mainstream cosmology papers.

 

I don't have a preference either way---just presenting an option

[Severian]

The most interesting thing to come out of WMAP lately is their evidence for inflation.

[KaiduOrkhon]

Er, a Greek philosopher, (Agustaros?) said: "There's always something larger than large and there's always something smaller than smal".

 

 

Einstein said that 'the universe is finite in space but unbounded in time' - I think that means that it may have finite parameters at any given moment, but that the parameters are endlessly enlarging.

 

There are still several variations on Steady State theory outside the restricted boundaries of the big bang; the (supposedly out dated; possibly reinstated) Steady State theory harbors no beginning or end.

 

There is a print-painting of a terrier looking dog with a sailor boy on a box of Crackerjack, holding an inevitably smaller box of Crackerjack, upon which is printed another image of what appears to be the same dog beside another - looks like the same - sailor, only smaller; holding yet another box of Crackerjack; with what would seem has a printed painting of another dog beside another sailor holding a yet smaller box of Crackerjack and so on...

 

It seems to go on forever, if the pictures could somehow be made ever smaller and still exist, as the visibly descending and/or ascending sequence of images certainly suggests... Geometrically squared rectangular boxes of heirarchically arranged Crackerjack containers and icons, out of infinite smallness proceeding to infinite largeness...

 

 

Perhaps an important representation of Einstein’s Unified Field without mathematics. Multi-moment space-time. An ensemble of constantly enlarging systems...

 

....an ever enlarging - and ever diminishing - blue & white terrier dog with a blue and white sailor boy holding a red striped box of Crackerjack with the image of a Sailor with a Terrier dog, may never again be the same.

 

Who said the ever-smaller sequenced pictures - smaller or larger, past, present & future - had to ‘end’, ever?

 

If the atoms of the universe of the past get ever smaller and the atoms of the universe of the present get ever larger and the painter or printer passed his job on from one generation to the next, where's the ‘end’ of the illustrated hierarchy of images - the multi-moment space-time ensemble of differently sized pictures of the same dog and sailor boy holding a box of Crackerjack with a picture of himself and his dog on it?

 

Same thing happens on a cylindrical container of MORTON salt, the byword of which is ‘When it rains, it pours." Meaning that humidity or dampness in the air does not prevent the salt from being smoothly dispensed from the container, or whatever shaker it may be contained by. The pictorial logo on this dark blue colored, cylindrically shaped package is a little girl in a yellow skirt, walking in the rain, holding an open umbrella over her head with her right hand; with a container of MORTON salt, pouring out of the metal spout cradled in and under her left hand and arm; upon which is the same pictorial; and so on; squared - same as the CRACKERJACK.

 

Then, there's Land O Lakes" butter and dairy products 'Where goodness begins'. It's an icon of a beautiful young Native American woman perched on a lake backgrounded - presumably Minnesota - mound of grass, offering a sample of the product - in this case, a pound of butter upon which she is the labeled icon; squared. It doesn't look like the Land O Lakes anecdote of 'Where goodness begins' has any explanation of where it ends... Yes. The same thematically endless heirarchy as the multi-moment 4-D MORTON salt icon - 'When it rains (water) it (Morton salt, still) pours', and, the CrackerJack Sailor - squared.

 

Einstein was caught up in a similar dilemma, only it was in Switzerland; back in the early 20th century.

 

The imperative that 'space has to end somewhere' may be as dogmatic as the Crackerjack sailor's K-9 companion. There's a lot of perspectives holding to the view that ('... must end somewhere!') space (space-time) doesn't really have to end at all.

(Sort of like this seemingly ubiquitous internet thread?)

 

Consider the word 'infinity'. Does it mean what it says, or not? Then there's 'endless', and 'pi r squared' and 'eternal'. There are words and equations and concepts that say some things needn't begin or end anywhere, contrary to the limitations of the anthropomorphic experience.

Perhaps these contentious words should be extirpated from all languages that express them. Perhaps the beginnings of these man made concepts should be brought to a proper and fitting end.

 

Of course everyone is entitled to their own endless ensemble of multi-moment space-time contained opinions... This post (unlike this internet residing thread?) has a beginning and ending for example. There's no denying it. It had to begin and end somewhere. (Squared.) - Refer, The Rise & Fall of Gravity, by K. B. Robertson

http://forums.delphiforums.com/EinsteinGroupie

[Martin]

The most interesting thing to come out of WMAP lately is their evidence for inflation.

 

Want to give a link to an article?

 

For people who just dropped in, the main article about the cosmological implications of WMAP3 data (the most recent release)

is Spergel et al. I will get the link.

 

http://arxiv.org/abs/astro-ph/0603449

Wilkinson Microwave Anisotropy Probe (WMAP) Three Year Results: Implications for Cosmology

D. N. Spergel, R. Bean, O. Doré, M. R. Nolta, C. L. Bennett, J. Dunkley, G. Hinshaw, N. Jarosik, E. Komatsu, L. Page, H. V. Peiris, L. Verde, M. Halpern, R. S. Hill, A. Kogut, M. Limon, S. S. Meyer, N. Odegard, G. S. Tucker, J. L. Weiland, E. Wollack, E. L. Wright

(Submitted on 19 Mar 2006 (v1), last revised 27 Feb 2007 (this version, v2))

 

"A simple cosmological model with only six parameters (matter density, Omega_m h^2, baryon density, Omega_b h^2, Hubble Constant, H_0, amplitude of fluctuations, sigma_8, optical depth, tau, and a slope for the scalar perturbation spectrum, n_s) fits not only the three year WMAP temperature and polarization data, but also small scale CMB data, light element abundances, large-scale structure observations, and the supernova luminosity/distance relationship. Using WMAP data only, the best fit values for cosmological parameters for the power-law flat LCDM model are (Omega_m h^2, Omega_b h^2, h, n_s, tau, sigma_8) = 0.1277+0.0080-0.0079, 0.02229+-0.00073, 0.732+0.031-0.032, 0.958+-0.016, 0.089+-0.030, 0.761+0.049-0.048). The three year data dramatically shrink the allowed volume in this six dimensional parameter space...

...The combination of WMAP and other astronomical data yields significant constraints on the geometry of the universe, the equation of state of the dark energy, the gravitational wave energy density, and neutrino properties. Consistent with the predictions of simple inflationary theories, we detect no significant deviations from Gaussianity in the CMB maps."

 

David Spergel is at Princeton. Ned Wright, another of the listed authors, is well-known to a number of people here at SFN---from his website, cosmology tutorial, cosmology FAQ, and online redshift calculator. He teaches at UCLA.

 

The WMAP3 results were embargoed until around 19 March 2006 and released simultaneously in the form of 4 major papers---of which this is the one having to do specifically with cosmology (kind of the general topic of this thread )

 

Another name I want to call attention to, in the list of authors, is Joanna Dunkley. She has a joint appointments at both Oxford and Princeton. Recently saw a video of a talk she gave last year and I was very impressed. She has written about the issue discussed in this thread----do we assume the universe is spatially infinite even if the data indicate that it could possibly be very large but still spatially finite? To what extent can making an unjustified assumption in this case skew calculation and distort findings?

[thedarkshade]

There is no way to make an infinitely small piece of matter. You could still make it smaller.

 

There is this limit for smashing everything into something smaller! For example you can smash a magnet till feromagnetic particles, but not smaller. And to matter as general, string (if it exists) is the limit!

 

I was thinking of the universe as spheric too. In all those graphs of the Big Bang you always see it progressing in one direction, when it should be in all directions. And that the whole thing is rotating putting us and all the other parts of the universe in different places in the universe, making us impossible to find out where we actually in the universe and find out where are the edges of the universe!

[yashti2000]

I believe that question will never be answered. Space is too big a mystery for us to handle for such a vain, ignorant race. We, as humans can't even solve our own worldly problems, much less even begin to understand such a question. I'm not a scientists, or a physcologist, or even a philosopher, so I cannot understand the mathematics, phylosophical, physcological, and religious aspects of even coming close to answering such a question. We can only guess as to what "WE" think may be the answer.

I am a religous person, so I believe it is not in gods plan for us to know these answers. Our minds cannot, will not comprehend it. I probably will offend people out there who do not believe in god, so if you don't like what your reading hear, then I suggest you stop reading. However, I will stand by my own opinion on this matter. I hope that there is someone out there who will look at this with an open mind.

I would like to know the answer to that question. However, I will have faith that answers to that question and the many thousands of other questions I have will be answered some day.

[Fred56]

Space is too big a mystery for us to handle for such a vain, ignorant race. We, as humans can't even solve our own worldly problems, much less even begin to understand such a question.

Here perhaps we see at least a heuristic conundrum:

Assuming that we are defeated before we start --by our own ignorance-- isn't going to (and hasn't anytime in the past) get us very far.

There are certainly problems, and we might be looking down the barrel to see that it is pointed back at us: for the first time in our history our 'disregard' for the planet we live off/on is maybe catching up with our concepts of 'unbridled growth' and human 'development' and learning.

But anytime in that past we have hit an environmental (resource-wise) wall we have usually found a way to exploit a "new" resource (e.g. agriculture), and now perhaps the new resource that will "save" us is the (so far) most "magical" (of the characters in the universal cast).

Perhaps the only thing that "really" exists is energy, and everything else (that we perceive) is an outcome of its existence...

[dshea241]

Please be patient enough to read all of this especially if you have expertise. I'm sorry that this is such a long post but I did read everything here and after reading everything here is my response starting with replies and then going on to the questions.

But if our universe is like a baloon, outside that balloon of what we know, our universe, how could there be an infinite void? There has to be something there eventually. That is an awefully conceited veiw. Our universe is the only area that is that has anything in it. Mathmatically speaking the area of our universe is a speck in the infinite expanse of space. The same way you and i are specks in the universe. You want to tell me that in pin-prick in space is where all the mass is. All the energy is. All the everything is.

 

Not possible...

 

Why do you think an infinite void is impossible but an infinite universe is possible? Why does the infinite void even have to be outside of the baloon, the universe is expanding in all directions. Where does the space that comes between us and the expanding universe come from? I put to you that it comes from the infinite void thats inside the baloon.

 

What's outside the universe?? I LOVE this one!!

You can't say there is a void or just nothing outside our universe. Because even nothing not even a void could exist outside it.

So to be accurate you've got to say, there's nothing at all not even nothing outside out universe, haven't you??

 

Very interesting. So by saying that a "true" void exists outside of our universe, your actualy saying that the universe is infinite? Sort of like a double negative in english (the universe is not not infinite) Or in other words, since nothing, not even nothing exists outside our universe then our universe doesn't have a nothing outside of it so the universe actualy doesn't end because it always has itself outside of it! Sorry if what I wrote is confusing but i'm sure you get my point.

 

These are a few different thoughts I came up with while reading through all of this. I hope someone can clear some of the questions and ideas I had. Please for any of my points correct me if i'm flat out wrong, or bring another point of view to the table if you simply disagree.

 

In 10000 years we will be able to see 10000 lightyears deeper into space. Our limit in looking back is time rather then distance. Would the universe become more like Olbers' paradox the further into the future we get?

 

 

This pre imagery should help you relate to what i'm about to try and exlain, visualize the next sentence and then read the next paragraph. Imagine looking at a spherical mirrored surface and what kind of reflection you see.

 

Lets say we could travel to the edge of the universe, and we travel from the edge of the universe at an angle 90 degress to the edge of the universe in a spaceship. As we proceeded into the "edge" of the universe I can imagine our ship being streched out in a kind of implosion/explosion where we cover the surface of the edge of the universe kind of like my mirrored ball example, wrap around the "edge" of the universe.

 

Maybe the universe is perspectivly flat (that whole 1, 1.5 WMAP shape of the universe stuff) but in reality is a Möbius "Sphere". Or is there math that goes against that idea?

 

If the universe is infinite then that would imply that it was always infinite. So was space infinite when it was a singularity or was there a switch (not infinite/infinite).

 

If space cureves in on it's self (if we could travel far enough we end up where we started). Would we be able to see into our own past. Also gravity seems to propagate at the speed of light, in the future would our gravity eventualy pull ourselves toward ourselves? And if that is the case I would think it would do so from all directions?

 

Maybe light doesn't travel, maybe light only seems to travel because gravity is pulling the light towards it. (slightly off topic)

 

My understanding of all these posts is that our universe may be a contained thing without any boundries. In other words, the universe isn't bounded "in" something, but at any given moment the universe is a mesurable size (though it is expanding). The idea that if you travel enough you end up where you started, well in a way that makes the edge of the universe a sort of half way point between your starting point and your ending point and then the end only depends on where you define the beggining.

 

[Fred56]

We might need to begin adjusting our concepts of "external" reality vs "internal". We continue to regard the world as an external (to us) thing. This extends to concepts of the universe being contained (in empty space). But there is no container --the universe is the container itself. Like mass/energy doesn't have 4 different "properties": (gravity,charge,nuclear 'force', superposition) --it is 4 different things. (The 5th thing --the weak 'force'-- is apparently part of the second thing --charge.)

[Spider]

This may sound stupid, but mathmatically speaking wouldn't it be an infinitely impossibility for there to be a finite amount of matter in a universe that goes on forever. There would eventually (in theory) have to be something else.

 

Those edges would just be our universes edges, right?

So, if you are right, then maybe there is a reverse galaxy where everything happens backwards and we go from say however old we would have actually lived to here so like 83 and age backwards to 0???

[MrMongoose]

Where one thing ends the next begins.

 

You answered your own question there. Where a finite subset of the universe ends, something, rather than nothing begins. That something is the next subset of the universe.

 

Whoops didn't realise this thing went beyond one page and had just been resurrected!

[thedarkshade]

This may sound stupid, but mathmatically speaking wouldn't it be an infinitely impossibility for there to be a finite amount of matter in a universe that goes on forever. There would eventually (in theory) have to be something else.

 

Those edges would just be our universes edges, right?

You mean finite matter in infinite universe? If you mean that, then finite fits in infinity, actually everything fits in infinity!

But first you're saying "universe that goes on for ever" than you're mentioning "edges of universe"! If universe goes on forever, then it must be infinite, because nothing can go on forever without being infinite! And if it is infinite, then I think it has no edges! I'm just assuming!

[Martin]

Lively discussion. It's good to consider all the various possibilities. In the context of conventional cosmology (the LambdaCDM model) there are two:

finite volume and infinite volume

 

the likelihood of one or the other is considered in the WMAP results paper I gave link to a few posts back. The errorbar favors finite volume slightly but not to a statistically significant level. It is very hard to tell the difference between infinite volume (on average flat or Euclidean 3D space) and a finite volume edgeless boundaryless space that is very large and therefore nearly flat.

 

Those are the two main possibilities that have emerged in professional cosmology, but there is no reason not to consider oddball exotic or just plain different ones----indeed a few professional cosmologists are always working on those as well, the field is not exactly monolithic!

 

In normal cosmology one always assumes matter is distributed roughly uniformly thru space-----so largescale averages look the same wherever.

Therefore in the finite volume case there is a finite amount of matter (spread more or less evenly)

 

And in the infinite volume case there is an infinite amount of matter. (Approximately evenly distributed throughout the whole infinite volume.)

 

In neither case can we see it all. We see only out to our observational horizon, which is limited in several ways (even in the finite volume case.)

 

If you go back to the initial post the question asked is Where does space end?. In normal cosmology the answer is NOWHERE, the mathematical model of space that is used has no edges. Even if it is finite volume it is boundaryless. I expect that several people have already pointed this out, me included.

 

Edges and boundaries are an unnecessary extra assumption that would just complicate matters, so one eliminates them by Occam's razor and common sense. Why make things harder for yourself. IT'S SIMPLE. Space is all there is. THERE AIN'T NO NOTHING.

[thedarkshade]

Thanks for all this Martin, if really helped.

 

Universe expands, this is something that now everyone knows, and what's interesting is that that expansion is accelerating (dark energy), but yet there is something that holds the universe together known as dark matter. But there seems to be not enough dark matter (23%) to pull the universe together, compared to dark energy (73%).

But will universe go on expanding forever? Will everything keep moving away from everything? One thing that makes me doubt about this is the fact that acceleration can't just go one increasing all the time. I understand that universe is infinite, and that everything fits in infinity, but hey, if this acceleration keeps on increasing all the time, at some point it will reach the speed of light, and what will happen then? Nothing can go faster than the light, or can it? And there's also dark matter, and maybe out there is more dark matter that we imagine and which at some point may pull this universe back together. Or is it that the universe will keep on expanding until this acceleration reaches the speed of light, and then all will come back together.

 

That makes you think, you know!

[MrMongoose]

In very simple terms, what evidence is there that the expansion of the universe is accelerating?

[Martin]

...

But will universe go on expanding forever? Will everything keep moving away from everything? One thing that makes me doubt about this is the fact that acceleration can't just go one increasing all the time. I understand that universe is infinite, and that everything fits in infinity, but hey, if this acceleration keeps on increasing all the time, at some point it will reach the speed of light, and what will happen then? Nothing can go faster than the light, or can it?

 

Some interesting questions here. We can't know the future. All we have is a cosmological model that is the best fit to the data so far. That is the LambdaCDM model. In that model expansion continues forever but (as it happens) never gets drastic enough to pull the milkyway galaxy apart or even to separate our galaxy from its nearest neighbor galaxies.

 

The acceleration that best fits the observation data so far is fairly mild, corresponding to a constant energy density of 0.6 joules per cubic kilometer.

This is not enough to ever threaten structures like the solar system which are gravitationally bound, or larger gravitationally bound structures like galaxies, or even our local cluster of galaxies. But it will eventually make the rate of expansion build up to where we lose the galaxies that are NOT bound to us. Like the Virgo cluster. We get to keep Andromeda, in fact it is expected to merge with Milky. But some other galaxies will gradually recede and disappear. according to the model that fits the data.

 

But always remember that we cannot know the future, we only know the future as predicted by the best model we have so far. More data could come in. The model could be improved to fit new data. Then it might predict for us a different future.

==========================

 

Not to worry about the special relativity "speed limit". It does not apply to recession speeds. RECESSION IS A PERCENTAGE INCREASE IN DISTANCES. So you can always find a large enough distance that it is increasing faster than c. This is not governed by special relativity, which applies only to stuff contained in a local frame of reference (not expanding, negligible spacetime curvature, approximately flat). Special Rel is a straightjacket that gives a bad approximation and so does not apply over very large distances, like billions of lightyears. General Rel takes over in largescale curved spacetime.

 

For example, we currently are looking at galaxies at redshift z = 6. Such a galaxy is TODAY receding from us at twice speed of light---2c.

And when the light that is now arriving to our telescopes left the galaxy and began its journey to us, the galaxy was receding at 2.75 c.

 

To get familiar with recession speeds, you might like to play around with Morgan's recession speed calculator some

 

http://www.uni.edu/morgans/ajjar/Cosmology/cosmos.html

 

put in 0.27 for matter density

put in 0.73 for cosmological constant

put in 71 for Hubble parameter (that stands for 71 km/s per Megaparsec)

and then put in whatever redshift z you want, like type 6 in the z box.

It will tell you the recession speeds then and now. And the distances. And the light travel time.

It is a good little calculator, embodying the standard LambdaCDM model, so you can get some hands-on with it.

 

Or rather, it embodies the standard LambdaCDM model if you put in those numbers. You can get drastically different behavior if you put in other numbers. (if substantially different from .27,.73, and 71).

 

Here's another take on it---another way to look at recession speeds:

Currently, distances are increasing all over the universe at a rate of one percent every 140 million years (except in gravitationnally bound structures like galaxies, which hold together)

So you can see that if you take a large enough distance, like over 14000 million lightyears, then in 140 million years it will increase more than one percent, which is more than 140 million lightyears. So it is increasing faster than c. More than one lightyear per year.

 

However that does not violate Special Rel, nothing bad happens locally. Nothing ever catches up with, and passes, a photon.

[carrotstien]

This is by far the most philosophical question of physics.

Possibilities:

 

1: The shape/size/geometry of the universe is something that we cannot actually mentally grasp so that we cannot say anything absolutely true about it.

 

2: Space is infinite in a way that you can, if you lived forever and space didn't blink out of existence for any unknown reason, travel in a perfectly straight line (somehow garanteeing that is perfect) and go on for an infinite amount of time without ever seeing anything perfectly repeat or every reaching a limit/boundary.

 

3: Space is something that is bent/warped in such a way that traveling in a straight line would make you eventually come back to the place you started.

 

4: Or space as we know is, is a piece of other space(s) which are inturn smaller pieces of other space(s) and so forth and so forth until one of the prior possiblities become correct (unless they never do in which case the box in a box in a box goes forever which is kind of like #2).

 

 

If its #1, then we can't even try to talk about it since by definition its something we can't even begin to imagine.

 

If its #2 then we get to a rather interesting peculiaraty mentioned earlier that makes the mass in the universe be a small speck/dot of volume of the whole infinite thing. (unless there are infinite packets of mass extending forever in this infinite universe. If there are an infinite # of packets then each packet would stay where it is because the gravity from other packets would be equal in all directions.)

Other than the small oddities #2 cannot ever be prooved since we or a light beam we shine can't ever get to the other end (which doesn't exist) and bounce back to let us know that its there (which it isn't)

 

#3 is my favorite since it, IMO fits perfectly which why the mass in our universe is expanding now. I will explain this at the end of this post. A problem that arrises from #3, or rather a couple of problems that arise are:

a. If it is bent, what causes the bending?

b. If it is bent in the nth dimension, what if we learn to travel in the n or n+1th dimension, can we go past the bend? (this of course is a byproduct of my mental cartesian thinking so it might not even make sense)

 

#4 is just as unprovable as #2 except now, you can say for certain that there is an infinit amount of energy in the whole universe of universes of universes of.... I don't like infinit energy cases of anything since they would allow perpetual work causing motion if we figure out how to harness energy from this infinit sink.

 

 

------------------

my theory on how #3 is beautiful

 

Lets say that the universe is warped in such a way, that if you were to subtract 1 dimension from all the geometries the universe would be shaped like a sphere. So that our 3d universe becomes the surface of the sphere. Some time ago, all the matter, for one reason or another was at a point. Now, for some reason or another, it went BOOM! And all the matter started moving away from this point. Lets say, that this sphere has a north pole and a south pole. Let the north pole be the start of the explosion. As all the matter moves away from the pole, its gravity tries to slow down expansion, and at the same time, gravity gets weaker and weaker. When all the matter is at the equator of this sphere, and if it still has kinetic energy, it will overshoot and keep going. When all the matter is at the equator, the gravititation force pulling all the matter towards the center of the expansion (the north pole) becomes very weak, and at the same time, equal to the gravitation force towards the south pole. Now, as the matter keeps moving the northgravity gets weaker, and the south gravity gets stronger, and the matter accelerates towards the south pole. Eventually all the matter will reach the south pole, be all at one small, or very small point/area, and then, for the same reason that it all went BOOM the first time around (or the last time around) it goes BOOM again and starts the process all over again.

Now, i don't have a phD in physics and i'm only going into my 4th term of college, but I have to say that this seems pretty logical for me. It doesn't require any weird black matter, or anti gravity and explains why our universe is accelerating its expansion, since this idea, if it was true, would mean simply that the mass in our universe as past the equator.

I guess this can be verified (since no experiment could actually prove anything) by comparing the rate of change of acceleration (which my math text book calls jerk ), to the rate predicted by this model.

 

- Roman R.

[thedarkshade]

As all the matter moves away from the pole, its gravity tries to slow down expansion, and at the same time, gravity gets weaker and weaker.

Why should gravity get weaker and weaker? The expansion should get weaker and weaker due to gravitational pull.

When all the matter is at the equator of this sphere, and if it still has kinetic energy, it will overshoot and keep going. When all the matter is at the equator, the gravititation force pulling all the matter towards the center of the expansion (the north pole) becomes very weak, and at the same time, equal to the gravitation force towards the south pole.

I don't get it! There's nothing at south pole, because the BOOM happened in north pole, and there was all the matter. There's nothing at south pole that would cause gravitational attraction.

Eventually all the matter will reach the south pole, be all at one small, or very small point/area, and then, for the same reason that it all went BOOM the first time around (or the last time around) it goes BOOM again and starts the process all over again.

I've heard something similar to this earlier, but this cannot go on for ever. After every "BOOM" there would be some loss of energy (entropy tends to increase), and loss after loss this BOOM scenario would always get weaker and weaker. The best model is that there was just one BOOM, and the idea that all the matter will ever get together again seems very hard to believe. Dark energy is speeding up the universe expansion and there is nothing that can stop that and pull it back together again. Dark matter could, but there is just not enough.

It doesn't require any weird black matter, or anti gravity and explains why our universe is accelerating its expansion, since this idea, if it was true, would mean simply that the mass in our universe as past the equator.

Well it should require "black" matter because we know it is there because of the gravity that causes. If you have a theory than you cannot leave out something that is certainly is there.

And there is no anti-gravity stuff!

 

Now what I posted seems logical to me too.

 

Cheers,

Shade

[carrotstien]

Why should gravity get weaker and weaker? The expansion should get weaker and weaker due to gravitational pull.

 

If after the explosion all the mass makes a circular distribution as you would expect from an explosion, then the gravity starting from the boundary of the distribution acts as though all the mass is at the center of the distrubtion. So, as the radius of distribution gets larger, each piece of matter gets further and further away from the center.

 

I don't get it! There's nothing at south pole, because the BOOM happened in north pole, and there was all the matter. There's nothing at south pole that would cause gravitational attraction.

 

If at any time all the matter forms a circular distribution, then the center of the circle along the surface of the sphere is at two points at all times. So, in a sense, a point at one pole, is a circle of a radius equal to half the circumference of the sphere with respect to the other pole.

 

I've heard something similar to this earlier, but this cannot go on for ever. After every "BOOM" there would be some loss of energy (entropy tends to increase), and loss after loss this BOOM scenario would always get weaker and weaker.

 

What is energy lose, friction, heat, em radiation. Besides mechanical energy loss, all other energy loss is due to em radiation, which you could imagine tries to spread itself out all over the sphere. (maybe we call this background radiation, sorry that i don't know enough about this to really be certain) Other than that, there is no energy loss from the system, if you define the system to be the whole surface of the sphere.

All things being equal, entropy isn't really related to energy and work, its just a measure of pattern-ness. There are infinit more unpatterned setups then patterned setups, so that it would mean that to make order, it is likely that some non random action is applied to change it from the more likely disorder. Imagine if I take a bunch of nuetral particles and position them to form my name. This is a very level of order you may say, but that doesn't mean that it took energy for me to make it, since if all the particles started motionless in a bag, and i moved them to their final motionless positions (relative to me as the observer) i did no work, and yet created an obviously un-entropic (?) situation. So, the fact that entropy tends to increase is just an logical observation that comes from the fact that an overwhelming majority of random actions, push a system away from order then toward order.

 

 

I don't like the idea of black matter, because it is something that our formulas predicts but something that has never actually been verified. Black holes make sense, and i'm pretty sure that we have observed enough stars at enough stages in their lives to see how a creation of one is very likely. Black matter - ok our formulas predict it, but do we have any other reason to say that its there? What if our formula so far accurately predict everything we have observed, but fail to accurately predict other cases (which we attribute to black matter)

 

Just as there is a unique polynomial of Nth degree that fits to a statistical data plot of N+1 points, and there are infinite polynomials of higher degree that fit to the same plot. If our formulas are analogous to a polynomial of slightly higher degree then the minimum, then we could be predicting something that isn't there.

[CPL.Luke]

one thing that most people don't realize is that the expansion is caused by a cosmological constant, and more importantly this cosmological constant is actually matter.

 

its a very strange type of matter that doesn't change in density as you change the size of its container, we know it either exists or general relativity is wrong, as otherwise the age of the universe doesn't come out right.

[phylumeister]

If we assume that the universe is expanding, (which it is according to modern day observations of light and also entropy), if it is always expanding, an end or edge will not exist since once it is reached somehow, it will just move farther out. Think of it as a race, the finish line would be like the edge, but if that keeps moving, assuming that you cannot jump over the edge, it would never have an end.