Thanks for the links, Phobos. Found me some food for thought
there.
(1) The line would appear infinite if that was all you could see as you walked it.
(2) This topic has been discussed at least once before. Try the SDMB’s search feature for “infinite” or “universe” or something like that. There has been some good discussions. One possible distinction may be between the words “infinite” & “boundless” (i.e., it may make more intuitive sense using the word ‘boundless’…in that you can never reach an ‘edge’ of the universe, but it still may retain some finite qualities.)
(3) Re: the early inflationary period…I think this means that the distance between two points was rapidly increased by that factor (adjacent points were suddenly that far apart).
(4) Mathematically, there can be different levels of infinity. Take for example, the number line. There are an infinite number of points between 0 and 1…which itself is just one step on an infinite number line. Our visible universe (the portion which we can currently see based on the finite speed of light) is likely to be just a portion of the overall universe. Combine this back with point (3), and it may just be that our bit o’ space had that rapid expansion, the other infinite extent may have also had that rapid expansion.
(5) Don’t rely too much on the balloon analogy. It helps, but it’s an imperfect analogy.
When trying to imagine expanding infinities, it may be best to take Douglas Adams’ advice and curl up into a corner and blither.
Sure. His whole website should be recommended reading.
http://itss.raytheon.com/cafe/cafe.html (main page)
http://itss.raytheon.com/cafe/qadir/qanda.html (Q&A)
Here’s a couple other similar good Q&A websites…
http://map.gsfc.nasa.gov/html/web_site.html
http://www.astro.ucla.edu/~wright/cosmolog.htm (good Q&A but the tutorial can get very technical)
I have to agree with the next post. For years now we have seen the universes matter’ expanding. Dark energy and dark matter try and describe using proposed solutions to as yet unresolved gravitational phenomena. So far as we know, the two are distinct.
Dark matter originates from our efforts to explain the observed mismatch between the gravitational mass and the luminous mass of galaxies and clusters of galaxies. The gravitational mass of an object is determined by measuring the velocity and radius of the orbits of its satellites, just as we can measure the mass of the sun using the velocity and radial distance of its planets. The luminous mass is determined by adding up all the light and converting that number to a mass based on our understanding of how stars shine. This mass-to-light comparison indicates that the energy in luminous matter contributes less than 1 percent of the average energy density of the universe. Dark energy and matter have never actually been seen.
Dark energy, on the other hand, originates from our efforts to understand the observed accelerated expansion of the universe. In a nutshell, current theory cannot explain the acceleration. One speculative possibility is that the acceleration is a consequence of another new form of matter, nicknamed dark energy, which has hitherto gone undetected. It is called “dark” because it must necessarily be very weakly interacting with regular matter–much like dark matter–and it is referred to as energy because one of the few things we are certain of is that it contributes nearly 70 percent of the total energy of the universe. If we can figure out what it really is, it is certain we will find a more illuminating name.
Either way if we can ever prove dark energy and matter to be true (there is some pretty good evidence they exist) there is no doubt the matter in this universe is expanding and moving away from other matter; expanding the universe.
If you care about science and seem interested in it you have to accept the evidence from all parts of scientific facts and not hold onto ones that back up your religious ideas. Some areas of science, like dark matter and energy, we’re just not positive about, but every telescope used to look at matter in the universe shows it to be expanding away from us (except the Andromeda galaxy which we should collide with in about 2.5 billion years).
Craig
In cosmology there is far more evidence for the big bang and none for the steady state theorem; things are not steady now and computers have “reversed time” to find all real matter had to have began at a point (as close as they can knowing what they do of the mass distribution); that’s certainly not steady state. If matter was being injected into the universe that would simply create for mass for gravity to pull things back inwards, not outwards. At first you said energy, but them mass; I’m pretty up to date with cosmology and that is a theory I have not heard of. It’s obviously extremely new or not being taken seriously in the scientific community; likely because it has no proof. Einstein was a man of god, but he spent many of his final years trying to find a unification theorem and because he believed “god does not place dice with the universe” he never solved his work. He refused to account for uncertainty and quantum mechanics. Rejecting Physics dogma compared with religious dogma is just being silly. Physics/science had given us and in most areas predicts an outcome before said outcome occurs. Religious dogma only repeats again and again what is in their bible.
According to the Planck mission team, and based on the standard model of cosmology, the total mass–energy of the universe contains 4.9% ordinary matter, 26.8% dark matter and 68.3% dark energy.
Many things about the nature of dark energy remain matters of speculation. The evidence for dark energy (see below) is indirect. However, it comes from three independent sources. These are:
Distance measurements and their relation to redshift, which suggest the universe has expanded more in the last half of its life.
The theoretical need for a type of additional energy that is not matter or dark matter to form our observationally flat universe (absence of any detectable global curvature).
It can be inferred from measures of large scale wave-patterns of mass density in the universe.
Since then, these observations have been corroborated by several independent sources. Measurements of the cosmic microwave background, gravitational lensing, and the large scale structure of the cosmos as well as improved measurements of supernovae have been consistent with the Lambda-CDM model.
Many observations have indicated the presence of dark matter in the universe, including the rotational speeds of galaxies by Vera Rubin, in the 1960s–1970s, gravitational lensing of background objects by galaxy clusters such as the Bullet Cluster, the temperature distribution of hot gas in galaxies and clusters of galaxies, and more recently the pattern of anisotropies in the cosmic microwave background. According to consensus among cosmologists, dark matter is composed primarily of a not yet characterized type of subatomic particle. The search for this particle, by a variety of means, is one of the major efforts in particle physics today.
Steady state though, I think now when direct telescope images show differently.
Craig
Energy is not being created nor destroyed at the quantum level, it is being exchanged between the two, but never destroyed or created, converted from mass to energy and then back to mass, yes.
As far as the universe being closed or open it doesn’t really matter. If open then we are just losing any chance of ever seeing that energy again, it was still within the “closed universe” (about 14 billion lights years being the closed part) when it originated, but even if you do not believe this all matter and energy was at one times much closer and yes much of that electromagnetic energy has been shot out into regions of the universe where nothing will reflect it, but it all started much closer and none has actually been lost, even in an open system, simply too far away for us to quantify/measure it.
Actually, according to most models of the dark energy, it is being created from nothing, but it’s happening in such a way that it does not violate the law of conservation of energy. Properly formulated, the law of conservation of energy is a purely local phenomenon, not a global one, and it is possible (so far as we can tell) to have a universe where energy is conserved at every point, but the total energy of the universe as a whole is not constant.
Our particular universe might technically have only a finite amount of energy, I suppose, but it had to come from somewhere, possibly pinched off from some other universe, and many think it has the potential to pinch off its own set of never ending daughter universes, so in that sense it has some kind of infinite potential energy. And then there is the idea that every quantum “choice” either creates infinite branching alternate universes, or that our particular universe is just a particular solution or collapse of an infinitely interfering waveform. I suspect that some sort of emergent property, possibly even life itself, will prevent heat death.
And that proper formulation is …
Roughly speaking, the change in the amount of energy within a box is equal to the amount of energy that flows through the walls of the box. But the Universe is not a box.