APOD: GRB 090423: The Farthest Explosion Yet (2009 Apr 29)

[DistantViewer]

OK, well, I guess it takes quite the education and the understanding into the calculations in determining all these distances. I understand your reply, and realized it did not explode when the universe was created, but there remains a nagging feeling that it doesn't all equate. O well, simple minds are not the best minds for such grand schemes.
Thanks for replying Chris, if anything it helped to think about it a little more.

[The Code]

Its amazing how it looks so global..


mark

[gshadducts]

I'm trying to follow along with Distantviewer's question. I'm trying to understand how two objects could be 13.7 B years away from each other 650 M years after the big bang. In my mind that would suggest that the universe was expanding faster than the speed of light. Let's assume that at time 0 the universe is a singularity. After 650 M years, even if it has expanded at the speed of light, the greatest distance between two objects at the edge of the universe could only be 1.3 M light years or essentially 2r where r = the radius of the universe from the point of the big bang.

Doesn't this finding suggest that the universe is much larger and much older than current theory? What am I missing?

Thanks for helping me understand. My brain is too small to get this

[Chris Peterson]

I'm trying to follow along with Distantviewer's question. I'm trying to understand how two objects could be 13.7 B years away from each other 650 M years after the big bang. In my mind that would suggest that the universe was expanding faster than the speed of light.

The objects weren't 13.7 billion ly apart when the Universe was 650 million years old. They were closer than that. It doesn't break any rules for two parts of the Universe to be separating from each other faster than c. During the very early Universe, it expanded much faster than c. The edge of the visible Universe is defined by the distance beyond which no signal can ever reach us, because it is receding too fast.

Doesn't this finding suggest that the universe is much larger and much older than current theory?

Current theory tells us very little about the size of the Universe. It is probably much larger than the visible Universe, and might be infinite. That's just not something we are able to determine given our present ability to make measurements. That may well change in a few years, but for now, nobody knows. The age of the Universe, however, is known to a fair degree of precision, and that age is well supported by multiple types of observations.

[brett_w7]

This is awesome stuff! I know I'm a little behind, but I just finished Hawking's "A Brief History of Time" and now I've started on "The Universe in a Nutshell". I highly recommend them, especially for non-scientists like me. He is the man!!! I hope he is recuperating!

Brett Walters
DBA
Harrisburg, PA

[aristarchusinexile]

This is awesome stuff! I know I'm a little behind, but I just finished Hawking's "A Brief History of Time" and now I've started on "The Universe in a Nutshell". I highly recommend them, especially for non-scientists like me. He is the man!!! I hope he is recuperating!

Brett Walters
DBA
Harrisburg, PA

John Moffat's 'Reinventing Gravity' greatly reduces the mind's load of consensus-spun cobwebs.

[The Code]

APOD April 29 2009

http://apod.nasa.gov/apod/ap090429.html
This was a big GRB? Is also possible to see the normal stars, along side at the same distance of 13 billion light years?

Mark

[Chris Peterson]

APOD April 29 2009
http://apod.nasa.gov/apod/ap090429.html
This was a big GRB? Is also possible to see the normal stars, along side at the same distance of 13 billion light years?

The fuzzy objects around the GRB afterglow are closer galaxies. It looks like there are a few foreground stars (from our own galaxy) in the image as well, although they might be galaxies. In any case, nothing else in this image is even close to being as distant as the GRB.

[The Code]

Thanks Chris..

That was the answer i was looking for, even though i missed a word.. thanks
This was a big GRB? Is it also possible to see the normal stars, along side at the same distance of 13 billion light years? Was what i wanted to ask..Your a good man Chris, and i respect every thing you say,,Thank you

Mark

[neufer]

Is it also possible to see the normal stars, along side at the same distance of 13 billion light years?

No!

• z = 8.15 : The most distant explosion: GRB 090423
  http://en.wikipedia.org/wiki/IOK-1
  
  z = 6.96 : The most distant galaxy: IOK-1
  http://en.wikipedia.org/wiki/IOK-1
  
  z = 6.43 : The most distant quasar: CFHQS J2329-0301
  
  z = 3.03 : The most distant galaxy protocluster: LBG-2377
  
  z = 0.08 : The most distant globular cluster
  http://www.sciencedaily.com/releases/20 ... 181358.htm
  
  z = 0.0045 : The most distant Cepheid variable stars (Virgo Cluster)

[The Code]

neufer...

Cant see any of those in the Apod photo, 13 billion light years away.. Cant see them ever getting a normal star/galaxy Image along side a GRB photo at the same distance EVER...In the same shot..

Mark

[BMAONE23]

I wuldn't think it to be possible until we have a telescope atleast capable of discerning spiral structure at a distance of Z-7 or greater

[Chris Peterson]

I wuldn't think it to be possible until we have a telescope atleast capable of discerning spiral structure at a distance of Z-7 or greater

We should be able to detect a supernova in just about any galaxy we can record. We should be able to detect the position of a supernova within any galaxy that we can actually image as an extended object. As for ordinary stars... well, we can only image those in the closest of other galaxies.

[isacki]

As a physics undergraduate in London, I've struggled with a lot of the same conceptual difficulties that some people here seem to be having, namely:
"How can we still see objects from (x) billion years ago if light travels... very fast?"

My own problem with understanding this was that I believed the light should have flown past us long before the present day. When I realised why it hasn't, I then realised why we can see absurdly distant objects, as far back as the very dawn of light.

I've come to a firm understanding about this, and this is my explanation of the issue. If I'm wrong, please continue my journey of learning!

What you've got to understand is what the true distance of the object really is. Remember distance/speed = time? Then the time it takes for the light to travel, which is the age of the observed object, is distance/c. Simple enough.

The true distance that matters for observing its light is the distance in spacetime, and this is a combination of how fast the object is receding from you AND how fast spacetime is expanding. Let me resort to a well-used analogy: spacetime is like a balloon. Put two marks a little distance apart on the balloon. Blow it up and they'll move apart, even though the marks haven't moved around on the balloon. So now think about if the marks were moving, too. The total distance moved is the sum of the balloon expansion and the distance moved on the balloon. And you can see that the balloon expansion can be a pretty massive part of this total.

Now we're in space, not long after the Big Bang. The two marks are your two objects. They are moving apart on the balloon - that's spacetime - but more importantly spacetime is being blown up. Not by you, of course, but by the Big Bang. And it's happening very, very fast (note: based on modern data the rate of this blowup is increasing). Therefore the true distance, just as for the balloon, is a combination of the spacetime expansion and the distance moved in spacetime. And you can imagine that spacetime expansion can be a pretty massive part of this total.

Remember "nothing travels faster than the speed of light"? What physicists clarify a little later on is "we don't OBSERVE anything travel faster than the speed of light". So let's consider what happens if we have our two objects moving apart, and we're one of the objects trying to spot the other.

Case 1: The distance is increasing faster than the speed of light. What happens? Well, we don't see anything, because light can't run that fast! No rules have been broken regarding "c being the speed limit of the universe", because we didn't see nothing, pal.

Case 2: The distance is increasing slower than the speed of light. What happens? The light eventually arrives at our position, after covering the distance, which will be covered in a time = distance/c. Now you can see that if the spacetime expansion and object speed is very great, as both are for very distant and ancient objects, this distance can become something very huge, resulting in a very huge time to wait, resulting in a very huge age. So long light can reach us wthout breaking the speed limit, we will see it. Some objects from the early Universe were receding too rapidly to be seen, but equally some were not. Hence, we can theoretically see objects back to any time when there was light. In fact, we do. The Cosmic Microwave Background is exactly that, and you see a bit of it every time you turn your TV on.

NB: As you probably know, the Doppler shift makes objects redder and redder, or longer wavelength, the faster they are receding. As their recession speed approaches the speed of light, they are redshifted out of red, out of the visible spectrum and into the infrared, then the microwaves and radiowaves. Eventually,when an object's light has to travel above the speed of light, it will simply disappear. A perfect example of this is an object falling into a black hole. As it approaches the event horizon beyond which no light can escape, the light becomes redder and redder, general relativity makes the object seem slower and slower, until it slows to a complete stop next to the event horizon, redshifted to the maximum, and any subsequent radiation simply... disappears.

NNB:So if light from an object has to travel too fast, you simply don't see it. This also means that there is a necessarily unknown number of galaxies that we simply will never see, because they are receding too fast from us. Their existence, bar any gravitational effect they may have had in the past, is nothing to us.
It's spooky.

[Chris Peterson]

As a physics undergraduate in London, I've struggled with a lot of the same conceptual difficulties that some people here seem to be having, namely:
"How can we still see objects from (x) billion years ago if light travels... very fast?"

My own problem with understanding this was that I believed the light should have flown past us long before the present day. When I realised why it hasn't, I then realised why we can see absurdly distant objects, as far back as the very dawn of light.

I've come to a firm understanding about this, and this is my explanation of the issue. If I'm wrong, please continue my journey of learning!

You seem to understand things just fine. Your description is very good, and is accurate. There's a name for the actual distance something is from us, because of the expansion of space: the co-moving distance. The co-moving distance to the edge of the visible universe is over 46 billion ly. Since the Universe is only 13.7 by old, this gives a good idea of the degree of expansion.

NB: As you probably know, the Doppler shift makes objects redder and redder, or longer wavelength, the faster they are receding. As their recession speed approaches the speed of light, they are redshifted out of red, out of the visible spectrum and into the infrared, then the microwaves and radiowaves. Eventually,when an object's light has to travel above the speed of light, it will simply disappear. A perfect example of this is an object falling into a black hole. As it approaches the event horizon beyond which no light can escape, the light becomes redder and redder, general relativity makes the object seem slower and slower, until it slows to a complete stop next to the event horizon, redshifted to the maximum, and any subsequent radiation simply... disappears.

A bit of a quibble here: the observed redshift of distant objects isn't Doppler shift, but cosmological redshift. The mechanisms are very similar, but not identical. We don't see cosmological redshift because of the recession velocity (which would be Doppler shift, but because the light has been stretched out during its trip through an expanding universe. And for an object falling into a black hole, the process is gravitational redshift. Again, similar but not the same as Doppler shift.

[aristarchusinexile]

NB: As you probably know, the Doppler shift makes objects redder and redder, or longer wavelength, the faster they are receding. As their recession speed approaches the speed of light, they are redshifted out of red, out of the visible spectrum and into the infrared, then the microwaves and radiowaves.

In other words, the Cosmic Microwave Background Radiation may not be the remnant of the Big Bang, but simply tired light, and was inserted into Big Bang theory to support the exhausted theory.

[BMAONE23]

NB: As you probably know, the Doppler shift makes objects redder and redder, or longer wavelength, the faster they are receding. As their recession speed approaches the speed of light, they are redshifted out of red, out of the visible spectrum and into the infrared, then the microwaves and radiowaves.

In other words, the Cosmic Microwave Background Radiation may not be the remnant of the Big Bang, but simply tired light, and was inserted into Big Bang theory to support the exhausted theory.

Ari,
This sounds like you are in favor of the expanding universe theory. For the CMB to be "Tired Light" or light that has been stretched into IR or Micro range due to a now observed faster recession speed would undoubtedly require an expanding universe to create stretch on the visual spectrum. Welcome to your first step towards BB

[Chris Peterson]

Ari,
This sounds like you are in favor of the expanding universe theory. For the CMB to be "Tired Light" or light that has been stretched into IR or Micro range due to a now observed faster recession speed would undoubtedly require an expanding universe to create stretch on the visual spectrum. Welcome to your first step towards BB :wink:

Unfortunately, not. The tired light hypothesis was created as an alternate explanation for redshift that didn't require the Universe to be expanding. It suggested that photons simply lost energy with distance traveled. The hypothesis didn't hold up, and pretty much nobody believes it anymore.

[aristarchusinexile]

Ari,
This sounds like you are in favor of the expanding universe theory. For the CMB to be "Tired Light" or light that has been stretched into IR or Micro range due to a now observed faster recession speed would undoubtedly require an expanding universe to create stretch on the visual spectrum. Welcome to your first step towards BB

I'm very much in favour of the expanding universe theory BMA as my spiritual reading says the galaxies are fleeing from the face of God, and Expanding Universe has been a part of my BEAGLE from its In The Beginning. However, my Bubbles of Expanding Antigravity Loosely Entitled theory not only accounts for expansion, but has no need for either the wild assumption of 'cosmic egg' or singularity .. everything in the universe beginning simply with quantum fluctuations in nothingness (learned from Pascual Jordan). Big Bang with its need for endless imaginative inclusions as new discoveries confound its believers is forever behind me.

[aristarchusinexile]

"... pretty much nobody believes it anymore.

Pretty much everyone believed earth to be the centre of the universe for 3,500 years.

[Chris Peterson]

"... pretty much nobody believes it anymore.

Pretty much everyone believed earth to be the centre of the universe for 3,500 years.

The reason that nobody believes the tired light hypothesis is simple. It can be unambiguously disproven for the cases where a known physical mechanism is proposed (such as Compton scattering, or some other scattering mechanism). Scientists take it very seriously when a hypothesis is actively disproven! That only leaves the suggestion of some completely unknown, unidentified physical mechanism- never a very convincing argument. In addition to the direct evidence contradicting the tired light hypothesis, there is the problem that it fails to predict at all a number of important observations, such as the effects of time dilation on distant events, and the shape of the spectrum of the CMB. These are all extremely serious defects in the hypothesis. It was a reasonable thing to look at back in the early 20th century, but it is pretty much impossible to take seriously today. Which is why almost nobody does.

And I'll point out once again, since you don't seem to get it, the Earth is the center of the Universe. The mistaken belief was that the Earth was the center of the Solar System. Not that it really matters, since that belief went out the door very quickly once the modern scientific approach was developed.

[The Code]

Until I come onto this Forum, and read everything posted. I now have different views. on even my own idea,s and i have to thank the forum for opening my mind. But I am very sorry, I can not believe the earth is the center of the universe, just like everything came from nothing, Until somebody slaps me in the face with undoubted facts .... The center of the universe for me will remain Eternia....

Mark

[Doum]

What i undestand from what Cris said is that the earth is obviously at the center of our visible univers. If you could move instantly a few billion years in distance then you would also be at the center of the visible univers overthere too. So, where ever you are in the univers you will always be at the center of the visible univers surounding you.

[astrolabe]

Hello Doum,

I couldn't have said it better myself!

[Chris Peterson]

What i undestand from what Cris said is that the earth is obviously at the center of our visible univers. If you could move instantly a few billion years in distance then you would also be at the center of the visible univers overthere too. So, where ever you are in the univers you will always be at the center of the visible univers surounding you.

That is indisputable. However, in a more general sense, it is likely that the Earth (or any observer) is also at the center of the entire Universe (not just the visible Universe), as long as we consider its 3D structure.