Is ours the only universe?

[C1ay]

Astronomers Chris Palma and Jane Charlton answer:

 

lefthttp://hypography.com/gallery/files/9/9/8/universe_391965_thumb.jpg[/img]Palma: There's a distinction that needs to be made here. When we loosely throw around the term "universe," usually what we mean is the observable universe, what we can see from here on Earth. We know roughly how old the universe is - the current number is 13.7 billion years. And we know the speed of light. So anything that is within 13.7 billion light years from Earth we can see because light from that object has had enough time to reach us.

 

How does this horizon - this spherical region that we can receive light from - compare to the size of the entire universe?

 

Charlton: Well, you've defined the observable horizon. Now let's define "universe." I ask my students to do this. And I think the best definition we've come up with is the universe is anywhere we could reach, given the ability to travel infinitely fast through space.

 

The distinction is a hard one for students to grasp. "What's beyond the observable universe?" I ask them. "What's out there? Is there no space and no time? Is there empty space? Or is there 'stuff' in space, like what we see within the observable universe?"

 

The definite correct answer is "there's stuff in space." We see to the place from which light has had time to reach us. To think that just beyond that point there's no more anything - that doesn't make any sense.

 

Palma: So the physical size of the universe, according to this definition, would be infinite, or such a large number that it's essentially infinite.

 

Charlton: In which case the answer is that there's only one universe. Except....there's inflation.

 

In the very early universe, things were different. Material was extremely dense, there was tremendous energy available, all sorts of weird kinds of particles could be created and physical forces didn't act the same as they do today. As time went on, the universe expanded and the energies available became smaller, and the forces started to act differently.

 

But the first transition was sudden, it wasn't a gradual thing. It was something like a phase transition, like when ice turns to water. And that leads to a phenomenon called inflation, where certain regions of space tap into the energy from this phase transition and expand exponentially, much faster than the speed of light.

 

Palma: Picture blowing up a balloon - you're adding air, you're giving it some energy, it's just expanding linearly. The idea is that there was a time very early on where the universe expanded suddenly, by this enormous factor in an incredibly short period of time. There was an instant where it jumped, and ever since then it's been expanding at a slower rate.

 

If you can picture this inflation happening once, why can't it happen multiple times? Why couldn't there have been lots of little pocket inflations in different places?

 

Charlton: And that would leave spaces in between all these balloons that could be stuck in the conditions that existed back when the physical forces were different.

 

It's a very different kind of space. We couldn't survive there, and we wouldn't see light from there. Almost by definition we couldn't get there, because it's too different.

 

So the real answer is: We don't know. There could be other universes with very different physical constants. But if there are, life will not exist there, stars will not exist there. Because it takes special conditions to make stars.

 

Palma: Stars and humans and other life forms in our universe are made out of carbon and oxygen and hydrogen. You can show mathematically that if the nuclear strong force [that holds together the protons and neutrons in an atom's nucleus] was just a little bit weaker, carbon and oxygen atoms wouldn't form at all. None of this would exist. It only takes a small change.

 

Charlton: As far as I know there's been only one good explanation of how these other universes could have similar physical constants, and that's if black holes spawn other universes. That's something that's talked about, that every star that dies in our universe that is massive enough to collapse infinitely, to just keep collapsing because nothing can stop the collapse, somehow that black hole breaks out into somewhere else - another universe, that may exist in other dimensions than our usual three dimensions of space and one of time. When that happens there could be a memory of the parent universe, and that might mean similar physical constants.

 

You need a whole course to answer this question.

 

Palma: At Penn State it's called Astro 120.

 

Christopher Palma, Ph.D., is outreach fellow in astronomy in the Eberly College of Science. He can be reached at [email protected].

Jane C. Charlton, Ph.D., is professor of astronomy and astrophysics in the Eberly College of Science. She can be reached at [email protected].

 

Source: PennState

[infamous]

Interesting article C1ay, similar ideas have been expressed by a few members here at Hypography.

[bumab]

Yeah, that article seems to speculate a lot, then say "but we don't know." Interesting, but somewhat unsatisfying :D

[infamous]

Yeah, that article seems to speculate a lot, then say "but we don't know." Interesting, but somewhat unsatisfying :D

Very true bumab, science is about discovering new data and facts, when the new facts are discovered, that's when satisfaction is realized. Scienctific knowledge is evolving right along with humanity, always something right around the corner. Anticipation don't you just love it??

[C1ay]

Yeah, that article seems to speculate a lot, then say "but we don't know." Interesting, but somewhat unsatisfying :D

Could you really do anything but speculate about what might be beyond the edge of the universe as we know it?

[alxian]

i always thought that man would find a way past the light barrier much as he has done so for the 50 mile an hour barrier and sound barrier etc

 

 

once we have become advance enough to do so we will voyage throughout the universe.

 

 

at that point the further we go the more of the universe we will be able to chart, meaning that the two most distant points of such a future could not actually see its furthest human settlements

 

 

that would mean travelling over 13.7 billion light years.

 

probably no doable.

 

but neither was the moon at one point.

 

i mean if we can send peeps out by 1 billion lightyears and ask them what they saw they are likely going to say much of the same, the barrier like the fog of war moves on and more galaxies become visible.

 

if man can figure out FTL travel via quantum froth wormhoels or even more exotic string theory methods maybe one day blinking will take longer than getting from here to the furthest human world from here, some 20-50-100 billion light years away?

 

just because spain can see the new world doen't mean its not there, just because out view of the infinite is limited doesn't mean the universe doesn't go on for trillions of lightyears in all directions.

 

 

 

the question then is the big bang... why does everything seem to be of a uniform distribution and age? could only this region of space be of that same age but other areas of the universe be older? and others even newer? could the visible univers be merely the remnants of a massive gamma ray burst or supernova?

[C1ay]

why does everything seem to be of a uniform distribution and age? could only this region of space be of that same age but other areas of the universe be older? and others even newer? could the visible univers be merely the remnants of a massive gamma ray burst or supernova?

Within the universe as we know it there are stars being born today and red dying galaxies that are more than 13 billion years old. There are globular clusters out there that seem to be even older than the universe as we know it. Everything is not as it seems.

[alxian]

Within the universe as we know it there are stars being born today and red dying galaxies that are more than 13 billion years old. There are globular clusters out there that seem to be even older than the universe as we know it. Everything is not as it seems.

 

meaning then that what we tell children has been true. the universe as we know it is growing and is as far as we can tell infinite

 

portion of it because of their composition have unusual spins on physics as we know them

 

what if in the realm of string theory the laws that govern physics down to the tune of the strings is slightly shifted in other places in the universe? more or less friction, light travels faster or slower, and new and unique forms of matter exist that in our part of the universe simply can't exist?

 

so while the universe as we know it isn't strange, it is not necessarily as old as we think, like humans, if you look at the population of earth without considering the dead you'd be inclined to assume that our species is only 100-200 years old, but we go much further back.

 

in that sense is there a way to judge the age of the universe by the structures left behind? like humans have cities and nations built upon the bones of the now long dead past do the current super structures leave evidence behind of their earlier periods? chemically it would be hard to tell, but if a group of stars seems to be growing out of what could have been the region remaining in the wake of a super nova then perhaps some of those regions can be dated further back than the existing starts would show.

 

it would also be interesting to hear that the strings if the theory is correct can be retuned, even if so slightly causing massive repercussions in the physical world we inhabit, if the force of gravity was tuned slightly stars and planets would decohere, the size of things would be altered, if the nuclear forces were to change perhaps atoms would be the size literally of beach balls planets or even stars.

[emessay]

GOD[=Alien but not cruel] loves STATISTIC so we have 99% 'unsatisfying' and only 1% 'satisfied' for us forever.

[emessay]

I remember Superman track-song : "Can you reach My Mind ?".......................................

What's really meant of 'beyond of unsatisfying' for our mind and it's quite similiar with our 'consciousness' compared with our 'primate-body', so what's differences among 'beyond of our universe' and 'beyond of our consciousness' ?? Perhaps we could imagine back again the way that Aristotle and Galileo have thought hardly about universe and nothingness.