Ever heard of a "Hyper" nova?

[Vraith]

What would be even more weird would be for there to be a sort of "edge of the universe" that acts like a black hole, attracting everything towards itself. To picture this, just imagine a hollow sphere and we are inside the sphere, with things being attracted towards the sphere itself. However, I am a mathematician and not a cosmologist so this is merely speculation.

[/color]

That would be weird...maybe more weird than you think "dark matter/energy" is...it would have to pull like gravity/black hole, but not be gravity...and it would have to expand as well [unless it's a permanent edge that we just haven't been sucked into yet], without weakening/becoming diffuse.

And SS: yes, Godel did just that [though I don't know about the birthday gift part]. However, though nobody has found any errors/impossibilities in it [AFAIK] it only works in a static universe...which ours doesn't seem to be.

[Loredoctor]

Lore,

For a Layman I'm pretty well versed in Astromonical phenomenons. Is this a relatively recent discovery due to investigations into Gamma Ray Bursts?

As far as I know, the first detection of a relativistic fireball/hypernova occurred in 2003 (GRB 030329), but there is a belief that past GRBs may have associated with a detonation of a star.

[Loredoctor]

The light or EM radiation we are perceiving started is journey to Earth, in your example, 50 Billion years ago. It took that long for the EM Radiation to get here. Therefore, the event we are observing is 50 Billion years in the past.

(Ignoring for the moment that this light started its journey 35 billion or so years before the Big Bang ... ) There seems to be something else that's not being taken into account here, something I believe Orlion may have been right to take into account: the expansion of the universe itself. If we're seeing something that is (let's say) 5 billion light years away, I'll grant that it took 5 billion years to get here. But does that necessarily mean that it happened 5 billion years ago? What about the extra time it took for that light to cross the increased amount of space? When this light began its journey, the distance between us and it was considerably less. If there was no expansion at all, this light would have come to us sooner, which means that the event didn't happen as long ago as it seems to us now. Right?

If so, is there some formula that takes this expansion into account, so that we can definitively say that object at X light years distant happened Y years in the past, so that Y=X-E (where E is the light years of expansion)? Or is the expansion's effect on light more complicated than that? Or is light unaffected in the amount of time it travels, and simply shifts to a lower frequency (red shift) as space "stretches?"

Cool post, Zara. From what I have read, the wavelength increases as space expands. However, there is a theory that the universe experienced massive acceleration early in its existence, which may have meant c+ speeds where space simply expanded faster than light. Some of the Type II supernovae studies lend support for this.

But I will have to look into the literature to be certain.

[SerScot]

Lore,

Are we certain the expansion of the Universe is undergoing acceleration? Is it possible we are misreading something?

[Vraith]

Lore,

Are we certain the expansion of the Universe is undergoing acceleration? Is it possible we are misreading something?

The early c+ expansion is one solution to account for current observations of the state of the universe, with some support...though AFAIK the exact mechanism hasn't been shown.

The current accelerating expansion, though, has been shown by independent observations over roughly the last decade.

But, my answer to Z's question still stands. 5billion light years does mean 5 billion years ago, there is no extra distance.
If you have a car that can only travel 1 speed: 60mph; it doesn't matter if the road is rubber and stretching underneath it. After 1 hour, it may LOOK, from outside/stationary like it traveled a different distance compared to a car on a concrete road. [hell, if you stretched the rubber road fast enough, it would LOOK like the car went backwards]. But if you were smart enough to mark the starting point on the rubber road, and you measured, you'd find it traveled 60 miles, and it took 1 hour [no matter how much/little the rubber road has stretched.]

[Orlion]

Vraith, your post reminded me of a short story I read, where rivals built a spaceship that traveled faster then light, went across the universe, and when they returned back home, their civilization had been dead for millenia. The explanation in the story was that even though they could see they were traveling faster, to the Universe, they were still traveling the speed of light. Trippy stuff.

[Zarathustra]

Cool post, Zara.

Thanks!

From what I have read, the wavelength increases as space expands. However, there is a theory that the universe experienced massive acceleration early in its existence, which may have meant c+ speeds where space simply expanded faster than light. Some of the Type II supernovae studies lend support for this.

But I will have to look into the literature to be certain.

Sounds like you're talking about inflation theory, which I thought has been pretty much accepted as fact. Wikipedia said this:

While the detailed particle physics mechanism responsible for inflation is not known, the basic picture makes a number of predictions that have been confirmed by observation. Inflation is thus now considered part of the standard hot Big Bang cosmology.

But, my answer to Z's question still stands. 5billion light years does mean 5 billion years ago, there is no extra distance.
If you have a car that can only travel 1 speed: 60mph; it doesn't matter if the road is rubber and stretching underneath it. After 1 hour, it may LOOK, from outside/stationary like it traveled a different distance compared to a car on a concrete road. [hell, if you stretched the rubber road fast enough, it would LOOK like the car went backwards]. But if you were smart enough to mark the starting point on the rubber road, and you measured, you'd find it traveled 60 miles, and it took 1 hour [no matter how much/little the rubber road has stretched.]

I find this problematic. It seems like you're saying that distance is absolute, even on a stretching road. How can you say with certainty that the car traveled 60 miles? Relative to what? If you're measuring it relative to other destinations on that road, then the distance is certainly changing. Its own odometer may register 60 miles (like my treadmill keeps track of my miles), but stars don't have odometers. Which is another way to say that space is relative, not absolute.

[Hashi Lebwohl]

The car Vraith mentions travelled 60 miles in its own frame of reference. The distance it travels to an observer in a different frame of reference will see it travel some other distance.

[Vraith]

If you're measuring it relative to other destinations on that road, then the distance is certainly changing. Its own odometer may register 60 miles (like my treadmill keeps track of my miles), but stars don't have odometers. Which is another way to say that space is relative, not absolute.

hmmm...ya know, if you were sitting here beside me, I could show you what I'm struggling to say in words with a pencil, paper, a piece of elastic in about ten seconds. It's not that space is absolute, it's that IN RE: your original pondering, it doesn't matter if space is expanding, contracting, or static...the solution will be the same in all cases, because the relationship between light/space is absolute...but because of the nature of light, not the nature of space. In simplistic terms, doppler colorshift [there are other kinds, but we can tell them apart] IS the measurement of spacial growth/shrinkage/static-ness. It's redshift in ours now, no shift in static, blueshift in a contracting. In any of those universes, anything seen 5billion lightyears away happened 5billion years ago.

[Zarathustra]

The car Vraith mentions travelled 60 miles in its own frame of reference. The distance it travels to an observer in a different frame of reference will see it travel some other distance.

Okay. But since an observer would measure it traveling some other distance, they'd also measure it as happening at a different time, too. Right? And that was my original point.

The universe is an accelerating reference frame, a non-inertial reference frame. Given this, we have to think about space and time differently:

Einstein's theory of special relativity, like Newtonian mechanics, assumes the equivalence of all inertial reference frames, but makes an additional assumption, foreign to Newtonian mechanics, namely, that in free space light always is propagated with the speed of light c0, a defined value independent of its direction of propagation and its frequency, and also independent of the state of motion of the emitting body. This second assumption has been verified experimentally and leads to counter-intuitive deductions including:

... relativity of simultaneity (simultaneous events in one reference frame are not simultaneous in almost all frames moving relative to the first).

...it doesn't matter if space is expanding, contracting, or static...the solution will be the same in all cases, because the relationship between light/space is absolute...but because of the nature of light, not the nature of space. In simplistic terms, doppler colorshift [there are other kinds, but we can tell them apart] IS the measurement of spacial growth/shrinkage/static-ness. It's redshift in ours now, no shift in static, blueshift in a contracting. In any of those universes, anything seen 5billion lightyears away happened 5billion years ago.

Okay, the redshift was one of the possibilities I mentioned when I asked the question, so I'm open to that answer. Maybe this detail stuck with me all these decades after my college physics classes.

But from the reference frame of the star itself, the light we're seeing right now wasn't emitted 5 billions years ago, right?

[Hashi Lebwohl]

Okay. But since an observer would measure it traveling some other distance, they'd also measure it as happening at a different time, too. Right? And that was my original point.

The universe is an accelerating reference frame, a non-inertial reference frame. Given this, we have to think about space and time differently:

Yes. If the frame of reference itself is changing, especially in a non-intertial way, then weird things like galaxies appearing to recede away from us at faster than the speed of light become possible.

[Vraith]

But from the reference frame of the star itself, the light we're seeing right now wasn't emitted 5 billions years ago, right?

A different, but connected problem, and I really don't understand it myself. What I recall/understood from others is that: it takes a very large difference in mass/velocity for time dilation to be significant factor.
[Roughly, Saturn is 9500% more massive than earth, but time is only 0.0000001% slower...I might be short one zero, and don't ask why I have those numbers in my memory]
The relation between time/mass requires lots of calculations, and they are non-linear. [so the ratio of time to mass of earth/saturn above is not the same as the ratio for other different masses]
Despite the difference in time flow rates, to the observer within that system, when they have experienced 5 billion years, the light will be 5billion lightyears away...like the flashlight being turned on when your ship is going near light speed: outiders see one thing, but to you, the light heads out from you at the speed of light...going one lightyear in one year.]

[Fist and Faith]

Seems like a good place to, yet again, quote Battlestar Galactica!

Brother Cavil: In all your travels, have you ever seen a star go supernova?

Ellen Tigh: No.

Brother Cavil: No? Well, I have. I saw a star explode and send out the building blocks of the Universe. Other stars, other planets and eventually other life. A supernova! Creation itself! I was there. I wanted to see it and be part of the moment. And you know how I perceived one of the most glorious events in the universe? With these ridiculous gelatinous orbs in my skull! With eyes designed to perceive only a tiny fraction of the EM spectrum. With ears designed only to hear vibrations in the air.

Ellen Tigh: The five of us designed you to be as human as possible.

Brother Cavil: I don't want to be human! I want to see gamma rays! I want to hear X-rays! And I want to - I want to smell dark matter! Do you see the absurdity of what I am? I can't even express these things properly because I have to - I have to conceptualize complex ideas in this stupid limiting spoken language! But I know I want to reach out with something other than these prehensile paws! And feel the wind of a supernova flowing over me! I'm a machine! And I can know much more! I can experience so much more. But I'm trapped in this absurd body! And why? Because my five creators thought that God wanted it that way!