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Hubble vs. Webb - How Far Back Will They See?
Roland Piquepaille writes "According to Forbes, reporting in "Peering Back At The Universe's Past," space telescopes are really acting as time machines. They can watch objects which are so far from us that light has taken billions of years before reaching their mirrors. The Hubble telescope is able to look at events that took place 13.3 billion light-years ago. But the James E. Webb space telescope, currently under construction, and scheduled to be launched in 2011, will be able to see even further and catch phenomena which happened 13.5 billion light-years ago. The astronomers think the Webb telescope might even be able to see up to 13.7 billion light-years ago, when our universe was just 200 or 300 million years old. We are used to see fantastic images from Hubble, without paying too much attention to the characteristics of the telescope itself. So here is a thorough comparison between the two space telescopes."
As I'm sure everyone will be quick to point out, lightyears isn't a measure of time, rather of distance.
It is more accurate to say that the hubble could see images 13.3 billion years ago, and the Webb telescope may be able to see images 13.7 billion years ago.
13.5 billion light years ago? Maybe I am being stupid, but I always thought that a light year was a measurement of distance?
Instead of 13.5 billion years back, why not make the mirror/etc a little bigger and see to the "beginning"? Or better yet, have the resolution to see farther than that, and see what happens? I'd be way more interested in that than a lame 500 million light-years farther than the hubble. Furthermore, is Arecibo unable to reach that far because of the atmosphere?
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If it's any comfort, the concept of "now" over those distances is meaningless in the context of General Relativity.
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I've got it. Here you've got a project that has produced some very good data and yet the creators have decided to stop maintaining it while they completely redo it from the ground up because they think the old base has gotten too "messy" to properly maintain anymore, disenfranchising the user base in the process. That's right all the signs are there, we must have just not noticed before, Hubble must be an open source project.
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The article states that the new 'scope costs about the same as Hubble, but will only have a 10-year lifetime, while Hubble is expected to be in service for 20 years.
Surely modern manufacturing etc should be able to improve on Hubble's lifetime for the same money? What am I missing?
...is an interesting thing, but a problem remains: it can't see events in the present (at far distances, obviously).
.03 is 3% but anyway
.1% improvement. .1% to .001% is a 10000% improvement.
Depends on how you look at it.
3 nines to 5 nines is
99.9% to 99.999% which is a
From the other end,
14-13.3 is 700M years after big bang
14-13.7 is 300M years after big bang
Better than 50% improvement (using Hubble as base)
Better than 100% improvement (using Webb as base)
The problem with percents is that they state one number and leave unstated the base for that number. Very little trickery is required to minimize or diminish importance without actually commiting falsehoods.
And if it doesn't work, we're all just going to sit down and have a good long cry together.
(I understand the logic, but I really like contingency plans...)
This is still if we have the space shuttles still flying and there are any left by 2010.
You're imagining the Big Bang as an explosion taking place in space. In this view there is an infinite, empty expanse of space, in which there is an explosion at one point which throws out all the material in the universe.
This view is wrong. If it was correct the galaxies would form a roughly spherical shell around an empty central region, at the very centre of which would be the Big Bang's 'ground zero'. We would therefore expect to see a great clustering of galaxies when we looked along the surface of this sphere toward our neighbours, and a great empty darkness 'above' and 'below' us. But this is not so; in fact the galaxies are very evenly distributed throughout all of observable space.
The Big Bang is more correctly viewed as an explosion of space, rather than in it. The Big Bang takes place simultaneously at all points in space, and it is space itself that expands thereafter, spreading out the contents of the universe and cooling the hot gas.
As a result, the light emitted from our region of the Universe in the Big Bang has indeed long since left the area, but we are now able to see the light emitted from the Big Bang in regions that are now some 13.7 billion lightyears away. Of course at the time they were much nearer than that...
We have, in fact, seen the Big Bang, or at least seen as close to it as we can ever hope to achieve. In the very early stages of the Universe, light could not propagate far; the universe contained a hot, dense gas of charged particles which was opaque to light. Once the electrons and protons combined to form hydrogen atoms, the gas became transparent and the light was released. This light has been greatly redshifted by the enormous expansion of space, and is now detected as a background glow of microwaves at a temperature of about 3 kelvin.
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Seeing 'back in time' has little or nothing to do with magnification.
The important factor is collecting enough light from a very faint source.
So the area of the mirror, the sensitivity of the camera and the directional stability of the system over time are what counts.
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It would very much depend on whether we are traveling away from the site of the big bang at the speed of light or not
If we are, then you should be able to see it, however, my suspicion is that we are not, and hubble can already see past the site of the big bang... maybe, timewise, it can see 5-6 billion years into the past at the actual site of the bang, but, although it's still getting older, everything you see past this point will be AFTER the bang.
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Also, you're perception of the past is wrong. If I'm a light-year away from something and see something happening, I can say that in my reference frame, that happened a year ago. Someone travelling at speeds approaching c might disagree, but that's another story.
And a light-year is a measure of distance. If you specify "the time it takes for light to travel a light-year" than you have a measure of time, but that was not what the original story poster wrote (although you could assume it since the telescopes are recieving light).