The size of the universe... scaled

[xelasnave]

Space is what is on the inside of the Universe which has no "outside".

[xelasnave]

As to science and religion.
Do not confuse seeking reality with the human need for structure and adherence to rules.
They can be seen as similar but one seeks to evolve and the other does not.
Will both be influenced by internal politics, well I suspect they would.

[sjastro]

Originally Posted by Weltevreden SA

Steven wrote, "Space can expand faster than light." This is oft-said and not-so oft explained. Why should space have a property which is essentially nonphysical until something physical expands to occupy it? Why, too, did space abruptly expand at at specific point in time, achieve the expansion velocity that it did, and slow to approx its present rate at a point in time so briefly after it began? What set the initial and ending boundaries? These issues have been floating without definition in my awareness for some time and this is a good occasion to address them. They are also very relevant: I’m comparing data re today’s cosmic matter-energy inventory (Fukugita et al) and Brian Lacki’s “CMD” of the energy sky (Fig 4), with a recent group of papers devoted to the properties of cosmic voids and filaments, Rieder, Alpaslan, Tempel, Libeskind. These introduce important issues, e.g., the large- to small-scale granularity of the products of inflation. But I note that all of these and others I’ve come across interpret space in terms of the interaction of mass density and energy density. Theirs is of course not the place to address what properties existed when there was space very high in potential energy density which endured an era 10 orders of magnitude in time in which no commensurate matter density existed. My question is not the hoary “Why is there something rather than nothing?” but “Why is space so small?” Steven, could you elaborate on some of these issues? It would help me no end.

Dana,

Regarding space there are two issues here.
Masses travelling through space and masses being carried by expanding space.

To travel through space work is performed in moving a mass from point A to point B which requires the expenditure of energy.
To accelerate a mass up to the speed of light requires an infinite amount of energy hence the speed of light is the upper limit for masses moving through space.

If the mass is being carried by space no work or energy is being expended as the mass is stationary relative to space's frame of reference.
From our frame of reference as the observer, galaxies with red shifts greater than z=1.4 have recession velocities exceeding the speed of light. From our frame of reference it is the space that is expanding, not the galaxies moving through space.

A canoeist makes a good analogy. A canoeist being carried by the rapids is expending no energy and is stationary relative to the water but moving relative to an observer on the bank.
If the canoeist paddles through the water he is expending energy and is moving relative to the water.

Expanding space isn't limited to the speed of light but the question arises where does the energy come from and how does it cause space to expand.
We can use the canoeist analogy again. The energy that drives the river is the conversion of gravitational potential energy into kinetic energy or in layman's terms rivers flow downhill.
Space is inextricably linked with a vacuum which is a field of the lowest energy state.
The theory behind inflation is that the Universe existed in a false vacuum.
The false vacuum has a higher energy state than a true vacuum.
Like the river analogy, the Universe dropped from this higher level to the lower energy vacuum state releasing energy and causing space to expand at an accelerated rate.

Inflation only accounts for a tiny piece of the space expansion mechanism, we have absolutely no idea about the current acceleration of the space through dark energy. Attempting to explain dark energy as another false vacuum effect has failed miserably.

What we do know however is how the behaviour of space expansion has changed in the past and is related to the interaction of gravity and dark energy on the Universe.
In the past when the Universe was smaller gravity had a greater influence than dark energy. At some point around 6 billion years ago, the Universe had become sufficiently large for dark energy to become the major player.

I'm not quite sure about your "Why is space is so small?" question, you will need to elaborate on the background behind the question.
Also I will need to study your links in detail before commenting.

And oh yes, since we are on matters of great magnificence and enormity, could you enlighten this non-Ozzie what the dickens a “Gish Gallop” is? =Thanks, Dana in S A

Alex has covered the topic nicely.

Regards

Steven

[Eratosthenes (Peter)]

Originally Posted by Slawomir

LOL

Then perhaps, as a result of laziness and other factor, too many blindly believe in it without questioning, while too few actually practice it.

Well science does have its priests, worshipers, temples, ceremonies and religious texts.

It does have one redeeming and special quality that distinguishes it from all other fundamentalist religious cults.

It is prepared to alter the contents of its bible and restructures its sermons to the people.

Is it astonishing to see what proportion of scientists don't even realize they are priests attending a church and reading from scripture. They stand out as they are offended at being associated with dogma and bias.

[xelasnave]

Peter you could be burnt on the stake for your views.
Science is somewhat under seige thanks to the net...so you are either with us or against us

[Eratosthenes (Peter)]

Xela,

I am well versed in the Scientific method. I know its limitations. I understand the fears and insecurities of scientists and researchers. I have been exposed to the ravages of political and corporate interference within the scientific domain.

I have never aligned myself with any tribal structures and its warm, safe and protective cushions. I am certainly not about to start now.

Are you aware that Science cannot explain how a bicycle works? (essentially why it is stable when a cyclists rides it).

[Slawomir (Suavi)]

I was not aware that bicycle cannot be explained - sounds like an interesting topic for a research, thank you.

Well, in the end, as far as I am aware, we still do not know what an atom looks like, what is light and why/how gravity works. Meanwhile mental problems are on the rise too; so much for our understanding of human psyche. To some degree, progress has been hindered by standardised education where curious young minds are programmed to memorise and accept information without any real and meaningful questioning. Anyway, by five cents worth of waffle.

[julianh72 (Julian)]

Originally Posted by Eratosthenes

Are you aware that Science cannot explain how a bicycle works? (essentially why it is stable when a cyclists rides it).

Ummmm... I'm a Structural Engineer, and I fully understand how a bicycle stands upright. Indeed, the principle is used in so many real-world applications that I can't even begin to comprehend were the claim comes from!

[julianh72 (Julian)]

How a bicycle works (spoiler alert!) :
http://www2.eng.cam.ac.uk/~hemh/gyrobike.htm

[Eratosthenes (Peter)]

Originally Posted by Slawomir

I was not aware that bicycle cannot be explained - sounds like an interesting topic for a research, thank you.

Well, in the end, as far as I am aware, we still do not know what an atom looks like, what is light and why/how gravity works. Meanwhile mental problems are on the rise too; so much for our understanding of human psyche. To some degree, progress has been hindered by standardised education where curious young minds are programmed to memorise and accept information without any real and meaningful questioning. Anyway, by five cents worth of waffle.

It was long thought that a bicycle gained its stability because of the gyroscopic effect, but helicopter characteristics discovered in the 1970s proved that theory to be an inaccurate explanation of bicycle stability. the "Castor Effect" was another theory that was popular but that was dismissed as well (by science). These theories, to be fair are incomplete theories in that they can explain bicycle stability but at different speeds. The latest theory I believe was tested at Delft University, with a specially designed bike which did not require the gyroscopic or Castor effect to work, and it still managed to move in a stable fashion. What the Delft bicycle revealed was that for it to be stable, it needed to be unstable, especially the steering. (the researchers dont know why this is the case)

I can sympathise with your comments on education. It is as if, the education system's main function is to bash out the natural curiosity and creativity of a young child or student. in order to push out automatons suited for the corporate world. Obedient and functional.

Its reflected in the type of fundamental research carried out in Universities and institutions. The research appears to be market driven, short term projects that can potentially generate profits, military research etc.

There doesnt seem to be any BIG idea challenges being tackled. Its reflected in some of the recent Nobel prize winners. A Nobel prize given for the invention of a blue LED (great as it is) just doesnt compare with those won by Dirac, Planck, Watson and Crieck, Shroedinger, Heisenberg, Pauling etc. Pioneers in fundamental research and profound ideas.

its sad to see medical research being driven by market forces and copyright etc. Money being poured into medical areas such as plastic surgery, rather than a disease which may effect a third world country (for example) - just no return for investors and bankers. Where are all the plans for space exploration?

Science still cant fully explain why humans require sleep - Oh Well back to the grind.............

[julianh72 (Julian)]

Originally Posted by Eratosthenes

Science still cant fully explain why humans require sleep - Oh Well back to the grind.............

When you look at the time stamps for a lot of the posts on the IIS forums, it would appear that some people no longer have a need for sleep!

[xelasnave]

Hi Peter
I did not know there were problems understanding "how a bike works", if I had realised I would have worked it out for them years ago.
But apparently great minds are engaged so I will leave it to them.
As to why humans need sleep ..that's easy...because they get tired.
Money makes the world go round and commands many motivations so what we see is is apparent corruption of what should be. Nevertheless the system manages
to produce usable results.
NASA are working on a "warp drive" that exciting, although I am suspicious that they really have anything, that must count as exciting and if it can be made work may change everything.g
I certainly get the impression science is like a religion but I think that view comes from behaviours exhibited on science forums who frankly have very few real scientists
participating.
I think the most important area is to find a quantum gravity theory.
I of course have worked it out but I want the others to work it out.

[speach (Simon)]

It's big very big. I feel that this is akin to 'counting how many angles can dance on the head of a pin'. The universe is expanding all the time, so it cannot have a finite dimension. If the expansion theory is held, conversely if it is expanding then it contracts back to a singularity, still we can't measure it's size. Because any measurement that we obtain will not be viable when we finish the measurement, the universe will have contracted further. In that case we could get a measurement but it would have to be at the Nano second the expansion changes to contraction. Not likely to happen. So let us suffice to say it's big very big.

[sjastro]

Originally Posted by speach

It's big very big. I feel that this is akin to 'counting how many angles can dance on the head of a pin'. The universe is expanding all the time, so it cannot have a finite dimension....

Expansion pertains to the visible Universe which we know is a finite size due the particle horizon being finite.
Whether the entire universe (observable + unobservable) is finite depends on its curvature. A positive curvature indicates a closed finite universe.

By measuring the angular sizes of anisotropic structures in the power spectrum of the CMB obtained by the Planck probe indicates the universe has a zero curvature and is therefore flat and probably infinite in size.

Steven

[speach (Simon)]

Originally Posted by sjastro

Expansion pertains to the visible Universe which we know is a finite size due the particle horizon being finite.
Whether the entire universe (observable + unobservable) is finite depends on its curvature. A positive curvature indicates a closed finite universe.

By measuring the angular sizes of anisotropic structures in the power spectrum of the CMB obtained by the Planck probe indicates the universe has a zero curvature and is therefore flat and probably infinite in size.

Steven

You're wrong, the question is 'the size of the universe' no qualification, of observable or unobservable.

[Eratosthenes (Peter)]

I believe it was Einstein (along with many other physicists and cosmologists)who described the Universe as "finite but unbounded"

(Boundary conditions and other assumptions are needed to describe the Universe in the mathematical realm.)

[sjastro]

Originally Posted by speach

You're wrong, the question is 'the size of the universe' no qualification, of observable or unobservable.

For a Big Bang cosmology the question itself does require qualification in order to provide an answer.

Please explain to me how you are able to conclude "The Universe is expanding all the time it cannot have a finite dimension."

[Eratosthenes (Peter)]

Has the universe always had a finite size?

Infinity conceptually, is nonsensical and indeed mathematicians refer to more than one "type" of infinity.

I am interested in whether the universe is bounded or unbounded. And whether there is only one universe.

An oscillating universe which is fluctuating in size would also produce observations which reveal that it is expanding (or contracting depending on what part of the cycle we are experiencing). We then extrapolate this expansion measurement back to time zero and assume there was a Big Bang.

We tend to like explosions.

Then we have the issue of the number of dimensions. It's difficult to conceptualise extra spatial dimensions past the 3 standard dimensions we are used to. (Plus time).

I have a gut feeling that not all is what it appears to be in the world of cosmology which is an ancient intellectual pursuit encompassing religions, philosophy, theology and science/mathematics.

String theory is a very good case in point of a theory which is still a mathematical philosophy, rather than a scientific concept. Scientific theories require observations, measurements, evidence to support (or refute) them.

[speach (Simon)]

Originally Posted by sjastro

For a Big Bang cosmology the question itself does require qualification in order to provide an answer.

Please explain to me how you are able to conclude "The Universe is expanding all the time it cannot have a finite dimension."

Simple, it's not expanding into something it's just expanding. You must get your head around the idea that to expand it must be expanding into an already created space. It's creating the space that it's expanding in to.

[sjastro]

Originally Posted by speach

Simple, it's not expanding into something it's just expanding. You must get your head around the idea that to expand it must be expanding into an already created space. It's creating the space that it's expanding in to.

Nice strawman argument.
Exactly where in this discussion did I suggest that the Universe was expanding into existing space?

Stop beating around the bush and answer my question.
How do you conclude a universe that is expanding all the time cannot have a finite dimension.