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knewtrino
2003-Sep-30, 02:24 PM
If we accept that nothing can travel faster than light and that therefore the universe is expanding at less than the speed of light does anybody know what happens to the light emanating from the universe that is presumably expanding at a rate faster than the universe itself? ie what & where does the light do & go to when it reaches the very edges of the expanding universe?

Hadrian
2003-Sep-30, 08:54 PM
I think there’s a theory that light is unable to leave the universe; something to do with the universe creating space and time as it expands. Therefore, outside the universe, there is nowhere for it to go.

Astronomers have seen what they consider to be the very edges of our universe, albeit, as it was billions of years age, and there seems to be nothing on the outside.

Consider this – you are standing outside on a clear moonlit night. You look up into the sky and know the sun is still shining, you know its light is blazing over the edge of the planet, yet apart from its reflection off the moon and other planets that might be visible that night, it’s impossible to see something which is effectively moving away from you at 180,000 miles a second. Light can only be seen from its source or when it’s reflected.

It could very well be leaving the universe for all we know, because without something to reflect it, light could effectively be doing a vanishing trick.

Some say there is nothing outside the universe; if this is so, then there’s another fine trick, a universe that is expanding into nothing.

Theories are alright, but theories are just that, they are what we are left with when we lack absolute proof.

Luddite
2003-Sep-30, 09:53 PM
I remember reading a theory on this topic and if memory serves me correctly the theory talked about a gravitational boundary at the edge of the universe. This gravitational boundary actually caused light that came in at an angle other than right angles to be re-directed on a circular path around that border. The light that did however travel at right angles to the border was slowed and directly reflected in the opposite direction. This theory behaves similar to the way that light trying to escape the event horizon of a black hole works.

mnc1916
2003-Oct-01, 04:52 AM
There is no edge to the universe. The very word universe impliesthat there nothing else no edge nolimit no mutple others nothing else universe is it. any variation enlargement change or whatever is merely an excersise in semantics and semanticsno matter its importance in intelecaldiscourse has no place on physics

astrophysicsrose
2003-Oct-01, 10:43 PM
I remember reading a theory on this topic and if memory serves me correctly the theory talked about a gravitational boundary at the edge of the universe. This gravitational boundary actually caused light that came in at an angle other than right angles to be re-directed on a circular path around that border. The light that did however travel at right angles to the border was slowed and directly reflected in the opposite direction. This theory behaves similar to the way that light trying to escape the event horizon of a black hole works.

Interesting concept. This gives the universe a beginning and an end. The edge of the universe is still keeping in accordance with creation inasmuch as the edge would seem to react much like the end in the event horizon of the black hole. Creation still knows no boundry like an edge or an end, it is consistent and remains creative into infinity, and if infinity does have an end or edge, then the edge in itself is still giving credence to life in consistency inasmuch as the edge or end would never end in a beginning that begins in life and ends inside of the event horizon of the black hole.

If this were a specific and verifiable reality, then wormhole space travel may be accomplished with area within creation to use as pathways or trails evolved throughout creation and space time. But, would there honestly be an end to the limit of interstellar travel throughout the living and consistently creative universe? Interesting concept, that an edge does exist, but, I feel that human conception of edge to something is mere human subjective perception. Human life has a beginning and an end. We are mortal, and our subjective perception of physics in itself is mortal as well. It has a beginning, and an end. How do we honestly know what ends where within the physics of the universe?

Human cognition itself has not as yet developed to the extent that we can even use our entire brain for thought processes. Therefore, if this is our state in life and in life within a living universe, then how can we honestly surmise or conceptualize an end or edge to a reality that we still cannot totally comprehend? There is more to this universe than our capabilities allow our minds to comprehend or even conceptualize. As we evolve as a species, more truths to what comprises life in the universe will unfold. For now, what we have is our mere subjective congnition of creation, reality, knowledge, and life in itself as we as humans know it.

imported_James
2003-Oct-02, 08:54 AM
It seems simple to me. The big bang blasted photons and mass in all directions from a point source. Spacetime was created as the wave front of photons moving away from the blast point with the majority of the mass trailing behind. In essence, our universe is like a balloon.

From another point of view, our universe is the inside of a black hole. Nothing gets out.

Another thing that keeps coming up is the number of dimensions. Nobody has ever been able to demonstrate more than the three spatial dimensions and the one temporal dimension that is spacetime. Just because someone's theory requires more dimensions to work does not mean the reality is anything more than we can observe.

The real question is, "What is spacetime?"

May the future be kind to you
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knewtrino
2003-Oct-14, 11:58 PM
Thanks to all for their input, I'm intrigued by the notion that the light in the "universe" behaves as expected inside a black hole - are we living inside what would be a black hole from another perspective?

Matthew
2003-Oct-16, 09:25 AM
We may be, we may be inside another universe. Maybe all black holes have smaller universes inside them. If so, then the only way to escape is to travel faster than the speed of light, and then obey the next universe's laws of physics. It wouldn't be that hard, would it?

imported_James
2003-Oct-18, 09:42 PM
The manipulation of spacetime is the first step. Diving into a black hole may not be survivable without the ability to bend spacetime. With the experience gained by getting out of black holes, the escape from our universe may become a possibility.

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Guest
2003-Dec-04, 04:02 AM
if we lived in a blackhole...wouldn't we cave in on ourselves?

Littlemews
2003-Dec-04, 07:48 PM
No, because its impossible to live in a black hole, besides, u can't even go through the Event Horizon......but one thing is ture u will disappear in the universe.

Matthew
2003-Dec-06, 07:34 AM
You can go through an event horizon. You leave the 'observable universe'. The event horizon is the point where events stop. But you will get through, at the end of the black holes life.

Dave Mitsky
2003-Dec-06, 11:34 AM
Originally posted by James@Oct 2 2003, 08:54 AM
It seems simple to me. The big bang blasted photons and mass in all directions from a point source. Spacetime was created as the wave front of photons moving away from the blast point with the majority of the mass trailing behind. In essence, our universe is like a balloon.

From another point of view, our universe is the inside of a black hole. Nothing gets out.

Another thing that keeps coming up is the number of dimensions. Nobody has ever been able to demonstrate more than the three spatial dimensions and the one temporal dimension that is spacetime. Just because someone's theory requires more dimensions to work does not mean the reality is anything more than we can observe.

The real question is, "What is spacetime?"

May the future be kind to you
Boycott SPAM

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According to standard Big Bang theory the universe never originated from a point source. That's the same as saying the universe had a "center". The BB was not in any way similar to a chemical explosion:

http://www.astronomycafe.net/cosm/bang.html

http://www.astro.ucla.edu/~wright/nocenter.html

http://www.astro.ucla.edu/~wright/photons_outrun.html

Comparing the universe to a black hole can confuse the issue (see http://www.astro.ucla.edu/~wright/cosmolog...y_faq.html#HOLE (http://www.astro.ucla.edu/~wright/cosmology_faq.html#HOLE) ) just as using the term edge can (see http://www.astro.ucla.edu/~wright/cosmolog...gy_faq.html#XIN (http://www.astro.ucla.edu/~wright/cosmology_faq.html#XIN) ).

Dave Mitsky

GOURDHEAD
2003-Dec-06, 05:09 PM
It is difficult to assign meaning to the concept of light or the behavior of light at the edge of the universe since the universe has no edge.

Matthew
2003-Dec-07, 02:01 AM
First you must know WHAT the universe is before you can start trying to work out how light works at the edge of the universe. If it has one.

TiMiX
2003-Dec-09, 11:40 PM
No one realy knows, but I feel we need to stop being so obsest with distances.

Just because the so called, end of the universe is so far away, we start thinking its going to be a totaly different place and have totaly diffrent rules to what we know here on earth, why would it??

I feel there is defintalty something beond the universe and it dosn't just stop, but it just changes into something else, to what is the big question but we need to learn how to see it.

Hunderds of years ago we thorght the our world was flat and it just stopped, all because we didn't know how to see it. But we have seen pasted that now and it now seems abit stupid to have thorght that. So why do the same with the universe?

Hopefully one day we will look back on now and think the same thing
and say, its was so easy, it was just looking us in the face to hole time! :rolleyes:

zephyr46
2003-Dec-10, 12:17 AM
Map of the Universe (http://www.astro.princeton.edu/~mjuric/universe/), I found this in a recent New Scientist magazine. The upper limits of detection strike me as limited only by the limits of our device, if the big bang theory is bunk (then I would suggest redshift has more to do with the longer wavelength, even the doppler effect adds evidence, IE Andromeda heading towards us :unsure: ) in which case we will see super clusters and larger quasars further and further away. Or we find the opposite edge of the big bang. Though the light from the opposite edge would be postponed by the speed away from us + our speed away from it/them.
Even at 300 000 Kmps light still will not get you to the moon in less than a second :)

rahuldandekar
2003-Dec-10, 09:03 AM
If we envisage the universe as a four dimensional ball with a three dimensional surface (for the sake of imagination imagine a three dimensional ball. It has a four dimensional surface), the light can only move on the surface, like a line we draw on the ground can only move on the surface. Thats why light never goes out of the universe or to any edge, as a ball has no edge.

GOURDHEAD
2003-Dec-10, 05:28 PM
Semantics becomes overwhelming. The definition of the universe used to be "all there is". We might carefully define the cosmos as all the "dimensionally unique universes in observational isolation from each other, if any. Sticking to the universe that we can observe and, to some extent, measure with rods and clocks, current theory posits that we can not observe all of it because inflation caused spacetime to expand faster than the speed of light thereby placing part of it forever beyond our reach observationally. If current expansion is accelerating, more and more of the universe will pass out of the limits of our observation even though the boundary of our observation is ever increasing because light has ever more time to travel an ever increasing distance. :unsure:

imported_James
2003-Dec-11, 08:26 PM
David Mitsky;
Your first link is interesting in that it is just a more complex way of saying the same thing I did. Your second link describes the volume of spacetime that we can observe directly. What proportion of the whole that represents depends upon your estimate of the age of the universe. Your third link begs the question, “What is CMBR?” I am not comfortable with the use of unexplained initials. For example, UPS has many meanings from United Parcel Service to Uninterruptible Power Supply.

What does a black hole look like from the inside? How about something akin to our universe? Think of the photon wave front as the event horizon. My balloon analogy is only as seen from the inside with the majority of the mass as the skin of the balloon with the rest of the mass as the gas inside the balloon. This mass inside the balloon will tend to be rarified and roughly homogeneous, just as we currently observe our surroundings.

Gourdhead;
Most people do not seem to know that a photon (including light) is a resonance between an electric field and a magnetic field.

Nothing goes faster than photons (light).

May the future be kind to you
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Dave Mitsky
2003-Dec-12, 08:59 AM
Originally posted by James@Dec 11 2003, 08:26 PM
David Mitsky;
Your first link is interesting in that it is just a more complex way of saying the same thing I did. Your second link describes the volume of spacetime that we can observe directly. What proportion of the whole that represents depends upon your estimate of the age of the universe. Your third link begs the question, “What is CMBR?” I am not comfortable with the use of unexplained initials. For example, UPS has many meanings from United Parcel Service to Uninterruptible Power Supply.

James,

If you'll do some further reading in BB cosmology you'll find that what you said is not correct. There was no point source, no center. Furthermore, it seems to me that you're misinterpreting the inflating balloon analogy commonly used to explain the Hubble Flow.

Two quotes from Sten Odenwald's article:

"So, how should we think about the Big Bang? Our mental 'fireworks' image of the Big Bang contains these basic elements: 1) A pre-existing sky or space into which the fragments from the explosion are injected; 2) A pre-existing time we can use to mark when the explosion happened; 3) Individual projectiles moving through space from a common center; 4) A definite moment when the explosion occurred; and 5) Something that started the Big Bang.

All of these elements to our visualization of the Big Bang are completely false according to GR!" (General Relativity)

"The center of the Big Bang was not a point in space, but a point in time! It is a center, not in the fabric of the balloon, but outside it along the 4th dimension...time. We cannot see this point anywhere we look inside the space of our universe out towards the distant galaxies. You can't see time afterall! We can only see it as we look back in time at the ancient images we get from the most distant objects we can observe. We see a greatly changed, early history of the universe in these images but no unique center to them in space."

Anyone familiar with the field or with a search engine for that matter would know that CMBR stands for the 2.73 degrees Kelvin cosmic background radiation which presumably is the microwave "fossil" of the energy released by the BB.

You can take your pick from http://www.dogpile.com/info.dogpl/search/web/CMBR or http://www.google.com/search?hl=en&ie=UTF-...oe=UTF-8&q=cmbr (http://www.google.com/search?hl=en&ie=UTF-8&oe=UTF-8&q=cmbr)

See http://www.astro.ubc.ca/people/scott/cmb_intro.html If you don't want to bother.

This is my last post on the matter.

Dave Mitsky

imported_James
2003-Dec-12, 01:29 PM
You seem to be looking at it from the outside while I am looking at it from the inside. There was nothing in your links that disagreed with me. The event created spacetime as it went along. The balloon, as seen from the inside, is expanding at the “speed of light” with the wavefront of photons. This expansion is continuing as there is nothing to stop the creation event. Why make the explanation more complex than it needs to be? You only confuse your readers.

:D What does BB (Ball Bearing) have to do with this topic? Is there a new use for the BB gun? :lol:

May the future be kind to you
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kashi
2003-Dec-13, 10:08 AM
My understanding of the balloon analogy, is that we are on the surface of the balloon (i.e. space time is wrapped around the outside of it).

rahuldandekar
2003-Dec-14, 06:33 AM
Thats right, and thats what I'm trying to tell here, that as the surface of the ballon (our three dimensional universe has no edge, so neither does our universe.

kashi
2003-Dec-14, 07:42 AM
The Universe is four dimensional. It's not like you can travel in one direction and come back to the same point. You'd have to travel through time as well. It's impossible to visualise.

imported_James
2003-Dec-15, 01:10 PM
It is time to bring this back onto the original topic. You, kashi, should realize that in my example, the balloon has no outside. The wavefront of photons from the creation event is creating spacetime as it goes. This wavefront is being followed by the majority of the mass of the universe. That is why the residual mass we can observe is still accelerating.

May the future be kind to you
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