What's the furthest object you've ever seen? How about 7.5 billion light years? - Calgarypuck Forums - The Unofficial Calgary Flames Fan Community

photon · 03-20-2008, 11:58 AM

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Holy Haleakala! Yesterday, a gamma-ray burst went off that was so bright that had you been looking at the right spot in the sky you could have seen it with just your own eyes!

...

So that’s what makes GRB 080319B (the second GRB seen on 2008 March 19) so incredible: distance measurements put it at 7.5 billion light years away, yet it was visible to the unaided eye had you just happened to be looking up at the sky at that moment.

http://www.badastronomy.com/bablog/2...e-visible-grb/

Totally mind boggling. The brightness of this is beyond fathoming.

flylock shox · 03-20-2008, 12:04 PM

Doesn't that mean that the GRB actually went off 7.5 billion years ago?

photon · 03-20-2008, 12:18 PM

I'm not sure actually, if it's physically 7.5 billion light years away that means taking the expansion of the universe into account that it happened less than 7.5 billion light years ago, but I'm not sure by how much. Good question for evman150, hopefully he sees this thread.

flylock shox · 03-20-2008, 12:24 PM

Well, unless someone can show me definitive proof the universe is expanding and not, in fact, balanced on the back of a giant turtle, I'm sticking to my theory about 7.5 billion years.

So basically, all these astrophysicists are just way behind the times.

MJK · 03-20-2008, 12:32 PM

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Originally Posted by flylock shox

Well, unless someone can show me definitive proof the universe is expanding and not, in fact, balanced on the back of a giant turtle, I'm sticking to my theory about 7.5 billion years.

So basically, all these astrophysicists are just way behind the times.

Isnt' the proof that it is expanding called "hubble's red shift"..the ability to measure how far stars are away from each other. Every single thing is moving away from each other...

It was explained to me like this:

The universe is like raisin bread expanding in the oven..each raisin is like a star and they are all moving away from each other.

???

JimmytheT · 03-20-2008, 01:06 PM

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Originally Posted by MJK

Isnt' the proof that it is expanding called "hubble's red shift"..the ability to measure how far stars are away from each other. Every single thing is moving away from each other...

It was explained to me like this:

The universe is like raisin bread expanding in the oven..each raisin is like a star and they are all moving away from each other.

???

Yes this is true. The evidence is almost irrefutable that the universe is expanding, and at a continually accelerated pace.

It may be safe to say however, that this gamma-ray burst actually occured prior to our Solar System's formation. We are witnessing an event that happened before our star was even in existence.

Burninator · 03-20-2008, 01:12 PM

The description of the energy expended in that burst is completely beyond my comprehension. It's like saying a ba-jillion x a ba-jillion + infinity squared = omg.

Wookie · 03-20-2008, 01:14 PM

Can this "raison bread" be replaced with chocolate chip banana bread. That I think would help me understand it a bit better, as well as being much more delicious. However, then our stars would be melting.

First thing I thought of too was that yes, this was visable yesterday, but it happened before I was born, did it not? Often these threads become to sceintific for me to follow within a few posts.

worth · 03-20-2008, 01:20 PM

I'm not a physicist but... it would have had to happen at least 7.5 billion light years ago. even though the universe is expanding, it is empty space that is expanding faster than the speed of light. photons cannot excede the speed of light no matter if the universe is expanding faster than the speed of light or not.

So yes, this GRB happened long before any of us were born...in face, it happened before this planet was formed and in fact happened before this solar system was formed.

I tell you what though, if you were anywhere in the vacinity of this thing, you'd be pretty dead. Luckly this sort of thing hasn't happened to our next door neighbours or we could be in some serious trouble.

Wookie · 03-20-2008, 02:07 PM

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Originally Posted by worth

I tell you what though, if you were anywhere in the vicinity of this thing, you'd be pretty dead. Luckily this sort of thing hasn't happened to our next door neighbours or we could be in some serious trouble.

I've wondered that before.

If our sun went supernova - how long to we'd be dead?

worth · 03-20-2008, 02:10 PM

I believe just over 8 minutes since that's how long it takes light to reach us from the sun...but that also depends on our orbit at that particular moment as it varies.

also, if the sun suddenly disappeared, we'd still be in orbit around it for 8 minutes as well as if it still existed. then we'd go floating off into space.

Bring_Back_Shantz · 03-20-2008, 02:21 PM

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Originally Posted by worth

I believe just over 8 minutes since that's how long it takes light to reach us from the sun...but that also depends on our orbit at that particular moment as it varies.

also, if the sun suddenly disappeared, we'd still be in orbit around it for 8 minutes as well as if it still existed. then we'd go floating off into space.

Nope, Gravity is instantaneous, the affects don't travel at the speed of light. If the sun just randomly disappeared we'd go flying off right away.

EDIT: Never mind, I was mistaken. You're correct.

Bring_Back_Shantz · 03-20-2008, 02:25 PM

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Originally Posted by Wookie

I've wondered that before.

If our sun went supernova - how long to we'd be dead?

Interesting tidbit, but our sun won't ever "Go Supernova", as its mass is much too small. It'll eventually blow off most of the outer layers and end up as a white dwarf, but this is a totally different thing than a supernova.

Geeky I know, but interesting stuff.

Also, don't worry, none of this will happen for a several billion years.

worth · 03-20-2008, 02:26 PM

Instantaneous gravity violates general theory does it not? So the only way that it can be instantaneous is if we add in parallel dimensions or other universes so that gravity can take a short cut or whatever. I'm pretty sure as we understand now, gravity has to travel at about light speed.

Newtonian gravity is instantaneous, but I don't think we use that anymore.

Bring_Back_Shantz · 03-20-2008, 02:30 PM

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Originally Posted by worth

Instantaneous gravity violates general theory does it not? So the only way that it can be instantaneous is if we add in parallel dimensions or other universes so that gravity can take a short cut or whatever. I'm pretty sure as we understand now, gravity has to travel at about light speed.

Newtonian gravity is instantaneous, but I don't think we use that anymore.

Hmmm, after checking a few things, i have to say, yup, I guess I was wrong.
I thought I had read otherwise, but I stand corrected.
my bad.

photon · 03-20-2008, 02:49 PM

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Originally Posted by worth

I'm not a physicist but... it would have had to happen at least 7.5 billion light years ago. even though the universe is expanding, it is empty space that is expanding faster than the speed of light. photons cannot excede the speed of light no matter if the universe is expanding faster than the speed of light or not.

Right, but those photons are stretched because of the expansion of space, and that redshift is what is used to determine the distance... so if it was 6 billion light years away when it actually happened and then space expanded by 1.5 billion light years during light's transit so that it took a total of 7.5 billion light years for the light to get here.

I'm just confusing myself I think

worth · 03-20-2008, 03:10 PM

Yeah you're right, but I think there's a net loss here. If the explosion occurs at 6B LY away and expansion takes place in between making it in reality 7.5B LY away at the point of contact with the earth we have to look at the fact that the photons are also traveling out at the same time. So wouldn't it be Expansion of the Universe - Speed of light (since the photons would be traveling out while space is expanding) = distance away from earth (when you add in the original starating position).

I don't think any of that made sense...

Fozzie_DeBear · 03-20-2008, 03:15 PM

I thought that Gravity was instantaneous...and quantum entanglement suggests that there is communication that is not limited by the speed of light...

(Essentially, if you split a photon so one goes left at the speed of light and the other goes right at the speed of light and then you measure the one on the left...the one on the right somehow 'knows' what you did to the one going left.)

worth · 03-20-2008, 03:27 PM

yeah, that's actually true. If you have a split particles and you measure one to be positive then you automatically know the other to be negative instantaneously. There's a lot more to it than that obviously...I think I read about this in one of Michio Kaku's books.

were getting into some higher end physics here though...or I guess I should say newer physics. We have a long way to go in physics, but I think as it is defined now, gravity is like a wave that travels at the speed of light. Just like when you throw a stone into a pond.

But then there's tons of other theories about membranes and parallel universes and reasoning as to why gravity is so weak.

photon · 03-20-2008, 03:39 PM

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Originally Posted by Fozzie_DeBear

I thought that Gravity was instantaneous...and quantum entanglement suggests that there is communication that is not limited by the speed of light...

(Essentially, if you split a photon so one goes left at the speed of light and the other goes right at the speed of light and then you measure the one on the left...the one on the right somehow 'knows' what you did to the one going left.)

Quantum entanglement shows that state between entangled particles can be transferred instantly regardless of distance, but you still can't violate causality that way; you can't use that to communicate information faster than light.

If you want to communicate using quantum entanglement to get the original information you still have to have some information that is transferred via a traditional method that's bound by the speed of light.