How To Build a Telescope That Trumps Hubble

An anonymous reader writes "In cleanrooms around the country NASA and its contractors are building the James Webb Space Telescope, a marvel of engineering scheduled to launch in 2014. This gallery shows the features that will allow Webb to take the universe's baby pictures in infrared — most notably an 18-segment mirror and a 5-layer sunshield. I can't wait until Webb settles into its Lagrangian point way out beyond the moon and gets to work."

Comments

The universe is infinite

[ubergeek65536]

So why do they thing that the universe isn't infinite? It seems that every time they get a bigger telescope the size of the universe gets bigger :\ Did they ever think that that big bang thing could have just been a localized event?

Re:The universe is infinite

[Ancantus]

Because nothing that we have observed so far is infinite, so its very hard to come to the conclusion that something is infinite without a base reference of what infinity really is.

Re:The universe is infinite

[ubergeek65536]

Tell that to the high school teacher that insists that they have proof because most articles and papers don't make the distinction between the the word universe and the term observable universe. Many astrophysicists don't even know the difference. Assumptions are not what science should be based on.

Re:The universe is infinite

[dkleinsc]

Why do you think it is infinite, without any proof whatsoever? All evidence we have is that the observable universe is finite, and observations of the early universe (thanks to the finite speed of light) match what the Big Bang Theory predicted. Ergo, it's the best answer we've got right now, and the burden of proof is on those who have evidence to the contrary to produce it.

Is it possible there's an unobservable universe outside of the observable universe? Of course. But you can't do science with it because it is simply impossible to observe.

Re:The universe is infinite

[melikamp]

If you regard infinity as a negative concept, you can also say that a thing is infinite as long as it's not known to be finite. The universe is infinite in this sense. One can even try to argue that everything material is, strictly speaking, infinite, and finiteness can only be verified for mental constructs such as mathematical objects. Considering that we do not know what exactly an electron is, it is at least possible that there are vast expanses of space-time folded there, extending forever into some exotic singularity.

Re:The universe is infinite

[ubergeek65536]

I have just as much proof that the universe is infinite as they do that it's not. That is to say exactly none. We will never be able to prove that it is infinite by measurement just and we will never be able to prove that it is finite. Like I said a hunch isn't exactly proof with either argument. A year ago the "universe" was about ten times smaller than it is now. Once the new telescope is functional I'm going to make the wild speculation that to will get bigger yet.

Re:The universe is infinite

[fishbowl]

Was space created by the Big Bang, or did the Big Bang happen inside of space that already existed?

Observe something that is more distant in space-time than the big bang, and settle the matter!

It is fine to speculate, but if you want coherent scientific models of the universe, you need to either assume the 13.7 billion light-year horizon or else show by observation or by theory that the horizon does not exist.

The ideas of an infinite theoretical universe aren't incompatible with a finite observable universe, but people who build telescopes are going to be concerned exclusively with the practical aspects of the latter, even if they believe in the former.

Re:The universe is infinite

[Zorpheus]

We can not see further than 13.75 billion light years because this is the distance that the light has travelled since the universe has become transparent. This happened 300,000 years after the big bang.
It does not really matter if it is infinite or not.

Re:The universe is infinite

[hedwards]

Actually, you're confounding the problem. The observable universe is always going to be finite until such a time as the observable universe and the universe are the same and the universe itself proves to have some sort of a limit in dimension.

I don't personally like the idea of confusing mass and energy with the dimension of the universe as you don't measure mass or energy with meters. If you're able to do that without any other units of measure, then you might have a point, but as it is there isn't any good reason to believe the things are related in that fashion.

Re:The universe is infinite

[msauve]

Why do you think it is infinite, without any proof whatsoever?

It all boils down to definition. What is the size of the universe? Is it the extent of space which contains matter? light? That is finite, according to our current knowledge, but is usually called "the observable universe." Is there something which prevents it from growing infinitely (aside from gravity and the potential "big crash")? Observations show the observable universe is still expanding, and there is legitimate argument that growth can continue forever (the "big freeze"). Doesn't that imply an infinite universe (beyond what is observable)?

What sort of "proof" would you demand?

Re:The universe is infinite

[hedwards]

It's only a sphere if it's finite in size, which is the problem. If you're defining the universe to be spherical then you're defining it to be finite in size. Which is largely fine at this point as we can't observe the furthest reaches that current theory predicts, but if we ever can see beyond it then we'll have to start really worrying about things like that.

Re:The universe is infinite

[bobs666]

IMHO, Astronomers forget to use the word visible, when they say universe. Given the Universe is expanding stuff we can see is exiting the Visible Universe all the time. So the result is the Visible Universe is shrinking. And one day there will be noting to see when you look up into the night sky. So I an told on Astronomy.fm

So if there another big bang overlapped our Visible Universe we might see a big corner of space blue shift. You can bet a lot of papers would get written about that.

To defend Astronomers You could say a big Goat head butted a fence and that kicked off the Big bag. Who could prove you wrong. Astronomers can't Observe that, so its speculation and an Astronomer will simply say We do not know What caused the big bang. We do not know if there was another big bang we can only see one. We only know about what we can Observe.

So you can speculate all you want. But until you can Observe another Big bang, the answer is no one knows.



PS.

Some people want a visible light telescope to replace Hubble. But think about it, Given you want to look far away, and that the farther away you look the faster things are moving away and thus are red shifted, so what was visible light is shifted in the infrared.

Got that? looking at infrared light far away is actually looking at what was visible light.

Re:The universe is infinite

[natehoy]

So why do people still think that a telescope magically expands the size of the actual Universe and ignore the important term "Known" or "Observed" that any decent astronomer uses when describing what they can see and observe?

Universe != Known Universe.

The definition of the size of the Universe is a matter of philosophy, religion, theory, or whatever term you want to use to describe "make shit up that we'll probably never be able to prove or disprove, so we can all safely argue about it from positions of held assumption".

The definition of the size of the Known Universe is a matter of observation, mathematics, and some margin-of-error guesswork because we don't have a yardstick of sufficient length. Every time our instruments get more powerful, we see further off, and the size of the Known Universe expands. The Known Universe will not, in any finite span of time with finite method of observation, be infinite. Meanwhile, the actual Universe may well be infinite, even possibly in ways we can't imagine (parallel universes, dimensions, etc). Or it may be finite, in which case it introduces a simple question - what is it bordered by, what's outside that border, and why isn't whatever is outside that border considered part of the Universe (you see, I struggle with the concept of infinity, but I struggle with the concept of the Universe being finite even more, but I'm just a dumbass programmer).

Re:The universe is infinite

[hedwards]

Precisely, it's pretty well established that we can't view all of the universe. Given the speed of light and that we're using light or various waves that travel at or near the speed of light, I think it's pretty inescapable that we aren't seeing everything. For all we know just outside our range of observation is a giant window in some sort of even larger department store display case. Sure it's incredibly unlikely, but beyond the range of what we can sense all sorts of weird things could be happening.

Re:The universe is infinite

[HotBits]

There is evidence that the universe is much larger than the observable universe (at least 250x), and is arguably infinite. Just because you can't see or measure it directly, doesn't mean you can't measure it indirectly: http://news.slashdot.org/story/11/02/01/2015250/Universe-250-Times-Bigger-Than-What-Is-Observable, http://www.technologyreview.com/blog/arxiv/26333/

Re:The universe is infinite

[melikamp]

Did they ever think that that big bang thing could have just been a localized event?

I am willing to bet money that they do (I am assuming you mean professional physicists). This guy, for example, thinks that bangs may be happening inside black holes, and new universes are created all the time, with parameters "inherited" from parent universes. This is almost an evolutionary interpretation of the largest-scale cosmology, with the parameters of our own universe being this way because other sets of parameters caused premature death (say, a big freeze) before new universes could be created. This is all great and I for one totally buy it up, but physics is already entirely too complicated, and no one wants to work with more complicated models when the simplest model agreeing with the experimental evidence is the incredibly-convoluted Lambda-CDM. So of course the Universe could be infinite or finite, flat or curved, expanding here and contracting elsewhere, or something we don't even have words for right now. To make a splash in physics, it's not enough to come up with an idea: you also need to exhibit a smoking gun.

Re:The universe is infinite

[ubergeek65536]

Actually, you're confounding the problem. The observable universe is always going to be finite until such a time as the observable universe and the universe are the same and the universe itself proves to have some sort of a limit in dimension.

That makes absolutely no sense. The universe is what it is regardless of what we think it is or whether or not we observe it.

Re:The universe is infinite

[timbo234]

For experimental/observational science 'the universe' and 'the observable universe' are the same thing, as by definition that's all we can know actually exists. If you think there's a distinction between the 2 terms you're the one making an assumption.*

* This is not necessarily a bad thing, there are many cosmological theories that feature the idea that there are vast areas of the universe beyond our current abilities to detect them. However all such theories are only at the hypothesis stage - currently without observational or experimental evidence.

Re:The universe is infinite

[WaffleMonster]

We can not see further than 13.75 billion light years because this is the distance that the light has travelled since the universe has become transparent. This happened 300,000 years after the big bang.

The distance light has really traveled is much much more than the speed of light as it is also dependant on hubble expansion..depending on your POV.. at some point in time and distance you reach a point where you can not see further regardless of the universes age because the portion of the universe under observation expands faster than the direct propogation of information. The universe (in terms of energy from the big bang) is currently hundreds of times larger than our directly observable universe.

Re:The universe is infinite

[bunratty]

I don't understand this idea you have that the amount of the universe we can observe is getting bigger. Since the 1960s, we've observed the cosmic background radiation. It's the thing farthest away we can observe, because before the cosmic background radiation became visible the universe was opaque. We have been able to resolve galaxies that are farther and farther away, but we knew that there was universe there. We just weren't able to see physical, gravitationally bound objects there before.

Re:The universe is infinite

[WaffleMonster]

For experimental/observational science 'the universe' and 'the observable universe' are the same thing, as by definition that's all we can know actually exists. If you think there's a distinction between the 2 terms you're the one making an assumption.*

This is incorrect. The observable universe is different at every point in the universe. A distant object under our observation may be influenced by events outside of our light cone which we can only indirectly observe.

Re:The universe is infinite

[Gilmoure]

Negative infinity makes my head hurt.

Re:The universe is infinite

[Gilmoure]

Maybe he's bounded in a nut shell?

Re:The universe is infinite

[peragrin]

I actually want both. The hubble is awesome because it has multiple camera's and can view objects in multiple wave lengths.

Infrared is good, ultraviolet is good, but you can't get some of the stunning images the Hubble has produced without some visible wavelengths as well.

What was that comet? Levy 9 that hit jupiter years ago?? only the hubble got good images off of that. James webb won't be able to do such things. So we need both or even better, both in a binocular fashion. So we can see the same image from the same spot in multiple wave lengths to really get a good idea of it.

Re:The universe is infinite

[ubergeek65536]

The background radiation is just noise and we will never be able to measure it with enough precision to make the conclusion that we see all of the radiation out there.
We have no way to know how far away that source of radiation is.

Re:The universe is infinite

[Nemyst]

You really don't know much do you? The radiation comes from the beginning of the universe, back when everything was a huge soup of particles. It's one of the greater proofs for the big bang theory, since there's no other reason for it to be there than to have one point where the universe was so dense it was irradiating in a nearly uniform manner. By studying the irregularities in the emissions, we can then learn more about that state in the universe's evolution, as well as what happened after that.

There's no distance to speak of because when those were around, they were everywhere and the universe wasn't of the same dimensions. We can measure that the universe is expanding, the big bang theory says there was a time where it was essentially a singularity, thus we can say (with good probability of being right) that the universe is finite.

Is it finite in the sense of a sheet of paper? Probably not. There won't be a wall with "the Universe ends here." written on it. Rather, it might very well be like the flat Earth theories: a loop that uses an additional dimension to complete. Whereas the Earth is a 3D object that was being represented as 2D (so you'd have edges even though they do not actually exist), it's very possible the universe loops around in another higher dimension.

Re:The universe is infinite

[TapeCutter]

IMHO, Astronomers forget to use the word visible, when they say universe.

I don't think they forget, I think they know it's redundant since traditionally "the Universe" (uppercase 'U') is everything, and "the universe" (lowercase 'u') is the visible universe.

Re:The universe is infinite

[Nemyst]

The observable universe doesn't "exist". It's just a construct, an abstraction we've created to describe what we, here on Earth, can see. It's not material. you could say it's just like a country's frontiers, something that matters for us humans but that doesn't really exist otherwise. The observable universe is finite because of the speed of light and the age of the universe. We cannot see what light cannot bring to us. With time, the observable universe will expand, since light from farther away will be able to reach us. However, the expansion of the universe might stop that light from reaching us, since we know it can be extremely fast for distant objects.

Also, we don't care about the rest of the universe. Only the observable universe matters, at least until we manage to get off this rock and change/expand the observable universe.

Re:The universe is infinite

[Nemyst]

You can count to infinity (though it would take an infinite amount of time). That doesn't mean you are infinite or the number you are counting is. In the same manner, the universe can be expanding forever without ever being infinite.

Re:The universe is infinite

[Nemyst]

He's defining it to be hyperspherical. Not the same thing at all. The hypersphere, or 3-sphere, is the mathematical step up of a sphere from 3D space into 4D space. It's to a sphere what a sphere is to a circle.

A hypersphere would seem infinite by our measurements, despite being finite if you move into a higher dimension.

Re:The universe is infinite

[bunratty]

You sound like Bill O'Reilly. Cosmic background radiation. You can't explain that.

Your argument is just like the arguments of people who disagree with evolution or AGW. You're just making stuff up to be argumentative. If you actually want to learn something, you can read about it.

Re:The universe is infinite

[Chris Burke]

So why do they thing that the universe isn't infinite?

Do you mean infinite in size, or infinite in age? Because the only implication of the summary or article is that the universe is finite in age. And there are pretty good theories with lots of observational support that suggest that the universe-as-we-know-it has a finite age.

It seems that every time they get a bigger telescope the size of the universe gets bigger :\

No, actually, that's not the case at all. Bigger telescopes have allowed us to see to points asymptotically approaching the theorized age of the universe, but it's been a long time since a bigger telescope has actually meant we had to revise our estimates of the age and size of the universe towards older.

So, you're base observation is off-base.

Did they ever think that that big bang thing could have just been a localized event?

Of course, also that it's just one Bang of a sequence that's been happening over and over, and other possibilities. However your specific case, that it's something "local" in a space-time sense, doesn't match the observations as well as theories in which it is that space-time itself erupted from the Big Bang, everywhere was "local" to the Big Bang, and it's only as space itself expanded that we can think of parts of the universe as not being local.

Re:The universe is infinite

[pclminion]

Was space created by the Big Bang, or did the Big Bang happen inside of space that already existed?

You ask it like it's some kind of unanswered question. Yes, space and time were created at the moment of the Big Bang. The question is HOW that happened.

Re:The universe is infinite

[ubergeek65536]

I do know enough to point out a flawed argument, that said all other facts are irrelevant. You've made the assumption that just because you couldn't think of a good reason doesn't mean that another reason doesn't exist. I did state that the near uniform radiation may only appear to be uniform because we lack the method to measure it with greater precision.

Re:The universe is infinite

[stevelinton]

Actually not. Suppose we can observe object A, which is influenced by object B. Then the light from B must have been able to reach A before the light that reached us left A. In which case that light could have got all the way to us.

Re:The universe is infinite

[stevelinton]

We have seen ligth (actually microwaves) from events longer ago and so more distant in space than the early galaxies Webb is targetting -- namely the cosmic microwave background. However there is a gap between that, and the most distant objects we can see in detail with Hubble. Webb is to look into that gap.

Re:The universe is infinite

[ubergeek65536]

Similarly the standard model is hugely useful but far from proven. Finding a model that works isn't proof.

Re:The universe is infinite

[ubergeek65536]

"radiation comes from the beginning of the universe". Another assumption. Did the universe even have a beginning?

Re:The universe is infinite

[khallow]

I did state that the near uniform radiation may only appear to be uniform because we lack the method to measure it with greater precision.

We already know that the cosmic microwave background (CMB) is near uniform not uniform. The perturbations in the CMB have been measured and are one of the attempts to say things about the parts of the universe that we can't observe (not being in our light cone), such as a minimum estimated extent of the current universe.

Re:The universe is infinite

[bunratty]

Science doesn't even attempt to prove things. The best science can do is find a model that works. If you want proofs, do mathematics. If you actually want to learn about how science is done and what science is all about, you can read about it.

Re:The universe is infinite

[jmuzz]

Yes, space and time were created at the moment of the Big Bang. The question is HOW that happened.

Easy, before the Big Bang there was nothing, when there is nothing there are no laws of physics, when there are no laws of physics there is nothing to prevent anything from happening.

Re:The universe is infinite

[oliverthered]

if you where travailing in a circle how long would it take you to reach the end?

pretty much everything is 'symmetrical' in one way or another, e.g. relativity has QM, random has determinate position has direction, energy has matter space has time or energy and matter have time and space, +ve has -ve (or -1 +2/3 -1/3 and the anti-particles), gravity has dark energy, up has down etc...

Re:The universe is infinite

[youn]

I think he's making a car analogy, talking about a negative infinity... a very bad car ;)

Re:The universe is infinite

[internettoughguy]

http://www.cracked.com/video_18254_bill-oreilly-teaches-kids-about-science.html

Re:The universe is infinite

[im_thatoneguy]

Actually mathematic proofs are based on assumptions as well.

Absolute knowledge is impossible since ultimately all methods of observation are subjective. But since all is subjective you have to sort of agree to accept the more obvious empirical data or reject *all* data.

Re:The universe is infinite

[TheTurtlesMoves]

There is a *lot* of evidence the universe is finite. The further back/away we look we see younger and younger galaxies at a different stage of their evolution. They *look* different and match predictions.

Re:The universe is infinite

[TheTurtlesMoves]

I hate it when people like you put AGW in there like it belongs. It doesn't, it has much less work done with it and is a long way from the rigor of the other examples. The models still have plenty of gaps and there are some pretty massive error bars in the whole thing. The idea you are not even allowed to be skeptical is also quite laughable, and a strong indication that its more politics than science.

Re:The universe is infinite

[hedwards]

True, but it's the same problem, he's defining rather than proving. And without some evidence to back it up, or even reason to take that view, it's pretty meaningless. I'm OK with speculation, but there does need to be some justification and or rationale involved. Given that we can't even see the edges of what we predict to be the size of the Universe, it's really hard to have anything intelligent to say about what might be really far out there.

Plus, the 4th dimension is time, and the fifth dimension definitely isn't spatial in nature. It's the dimension that's necessary for non-deterministic reality to happen. Basically the dimension which allows for all the freaky quantum stuff to happen without our seeing it directly. Which is one of the reasons why hypercubes and things like that are such strange things. It's unlikely that there are 4 dimensions in this reality that are all measured in meters.

Re:The universe is infinite

[dtml-try MyNick]

This is the part that always gets me..... the "nothing"

I understand that "nothing" is a concept that is very hard to grasp for a human being, but still...

As far as I understand the big bang is a series of events that led to the creation of our current universe. The part I can't get my head around is how "nothing" can turn into "something".
It seems to me that an event like the big bang had to be triggered by at least ''something". And that that "something" must have had some form of physic laws in order to trigger the event.

Easy, before the Big Bang there was nothing, when there is nothing there are no laws of physics, when there are no laws of physics there is nothing to prevent anything from happening.

This is kinda what I mean.
In my (surely overly simplified) logic for "anything" to happen there must be "something" to begin with in the first place. But all I keep reading is that that is not the case.. And *that* boggles my mind almost to explosive levels ;)

Disclaimer: I'm just a layman who tries to get his head around theories like this purely out of interested (and is failing horribly most of the time)

Re:The universe is infinite

[jandersen]

There's a lot of unclear and contentious issues at work here, I think; and unfortunately I don't know enough to gve an informed opinion on it all, but ...

Was space created by the Big Bang, or did the Big Bang happen inside of space that already existed?

Observe something that is more distant in space-time than the big bang, and settle the matter!

"Space" is only a convenient mathematical model of reality - mathematically a space is loosely speaking a set with some topological structure. In all our current models "space" is assumed to be a pseudo-Riemannian manifold - more or less - and as far as I know, any such thing can be embedded in an Euclidean space of higher dimension; don't ask me about details, I am on thin ice here.

So, I think in a sense the answer depends on which viewpoint is convenient. I recently read some articles about this, in Scientific American or possibly New Scientist, which suggest that there may be evidence that there is something beyond the boundaires of our universe. Again, thin ice - very thin :-)

It is fine to speculate, but if you want coherent scientific models of the universe, you need to either assume the 13.7 billion light-year horizon or else show by observation or by theory that the horizon does not exist.

This horizon is a consequence of the speed of light and the age of the universe - light from further away simply hasn't reached us yet. This doesn't mean that there isn't more of the same out there. The real question here is whether there is a finite amount of space - ie whether there is a maximum to the set of all distances between pairs of points in the universe. we just don't know; also, what definition of distance are we talking about? The Euclidean distance between two points in the 3D part we call space, as measured from an Euclidean space in which out universe is embedded? Or the lengths of 4-vectors? Or ...?

It's not just a difficult question to answer, it is actually quite hard to ask as well.

Re:The universe is infinite

[lpq]

Then that is the fault of science.

In all the infinity that that is -- whether that be endless nothing beyond our 'universe bubble' (but why it wouldn't be equally likely to be an endless series of self-contained universe bubbles, is beyond me).

And that's where 'faith' can enter into science. Thinking that 'science' does anything other than predict conditions in the little speck of universe that we know about -- and nothing about the volumes beyond -- and that some people lean toward believing that our universe is unique because that's all science can prove?!? : yeah, and the universe still revolves around the earth!

All the evidence we have the the universe ends at some point is based on the fact that we can't see any further, and the further you go away from us, the less we can see and the younger the boundaries of this universe look. What does that tells us about what's beyond that range? Zip, as near as I can tell.

Re:The universe is infinite

[jo_ham]

Who says you can't be skeptical about AGW? That's never been the argument.

The reason it appears so is because there is a vast imbalance in the two "sides" of the AGW debate regarding scientific knowledge and understanding of the way science works. On the one side you have actual scientists, on the other side you have people (often high profile TV and radio hosts) where the level of scepticism is on the order of "well, look at all that record snowfall we had last night! so much for this so-called "global warming" eh?!"

There's a difference calling out that sort of "contra evidence" as rubbish and pointing at the large propaganda machines that fund the anti-AGW movements. The weight of politics in the debate is far, far swung to the one side (but it clearly not absent from the other side). A large number of skeptics are asking to be weighted at an equal level to that of professional scientists when they really have no business or expertise in that field. It's all very well "offering the other side's point of view" - just because these non-science detractors, or those who haven't even looked at the evidence but still argue against it on "common sense" arguments (like 'the earth is so big, there's no way we could be affecting its climate') or who demonstrate their knowledge of science is shaky at best (the moon! you can't explain that!).

Science is all about listening to skeptics. Challenging your model is the way you make it better so that we *can* explain those gaps, or look at areas we didn't understand before with fresh eyes and different ideas. That has never been in dispute, and actual climate scientists (and others who work closely in the field like physical chemists and spectroscopy experts whose areas of study are not just confined to the Earth's atmosphere or atmospheres in general) have never worked from a platform of "you're not allowed to criticise us". In that respect it is no different from any other area of science. The only difference is that it has a serious amount of political and commercial baggage attached to it, with a large number of special interest groups who are not pleased that the science seems to be telling them things that are not profitable or politically convenient to hear.

If you (the general you) have any scientific criticism of the models used in the AGW and climate change in general, then scientists want to know - it's an area of interest that has been refined over decades, and is getting better all the time. You (again, the general you) might want to start from the generally accepted model that increased CO2 in the atmosphere absorbs IR, and that the mean average temperature has gone up, and if you fill a greenhouse with steadily higher partial pressures of CO2 and measure the effect on the temperature the results are clear. Add to that the fact that the CO2 concentration has jumped far, far above the highest level it has ever been in 600,000 years and you have to conclude that humans are *likely* to be responsible for that. If there is another model that explains it that can stand up to scientific review then they are open to hearing it.

The trouble is, much of the criticism is aimed at the scientists themselves, or just doesn't understand the data that is presented - science has always had an image problem, especially in conveying results to ley people, and this weakness has been expertly exploited by those with an agenda to push.

Re:The universe is infinite

[Internetuser1248]

Because nothing that we have observed so far is infinite, so its very hard to come to the conclusion that something is infinite without a base reference of what infinity really is.

The fact that it is logically impossible to observe anything that is infinite tends to dispute that as an argument. It is similar to a blind person not believing in colour, sure it is understandable, but it can not be claimed as a logically strong position. It is a tautology that we have only observed finite things, as observation is finite. Another example might be to say that in the 1800s colours didn't exist because no photographic records of the time show any colour. It is however a valid point to say that we don't have a reference for what infinity really is. It is a difficult subject as without a knowledge of infinite, we also don't have a real base reference for what "not infinite" means. Perhaps the whole question should be left to philosophers and theologians and the scientists should stick to evaluating evidence and claim no opinion where there is none.

Re:The universe is infinite

[bunratty]

Yes, axioms are taken to be true without proof. But given that a handful axioms are true, you can write many proofs. That's as close to a "proof" of anything that I think we can ever come up with.

All we can know for sure about reality is "I think, therefore I am." The anti-science crowd likes to point out when the science is not settled when there's a conclusion they don't like. They still don't understand that science is never settled. All we have is the best working hypotheses so far. If they want to argue that those hypotheses are not correct, they should come up with better hypotheses, instead of saying "Well, you didn't prove it, so I refuse to believe it! Neener, neener!"

Re:The universe is infinite

[bunratty]

You can certainly be skeptical, but I see hardly anyone who is genuinely skeptical about AGW. I see lots of people who simply refuse to believe it, no matter what evidence is presented. They even argue that the evidence is all wrong. It reminds me of ID proponents who argue that all hominid fossils are fakes. As to your claim that much less work has been done on AGW, I should again point out that the hypothesis is over 100 years old, and all our observations and research are in agreement with the hypothesis. If you have some actual evidence that disagrees with AGW or a better hypothesis than AGW that explains the warming, let's have it. I have yet to see it. Don't throw a fit and say "You're not letting me be skeptical! Waaaa!" You sound like a baby. Present your argument. I have never seen a good one that suggests AGW isn't happening, but maybe you have something new.

How To Build a Telescope That Trumps Hubble

[Anonymous Coward]

Put a bad toupee on a telescope.

Budget Cuts and the JWT

[Petersko]

The budget cuts announced by Obama include cutting $64 million from the James Webb Telescope program, "which an indendent group of experts "found to have a fundamentally broken estimate of cost and schedule".

While I recognize the U.S. is totally fucked, economically, this is a mistake. Throwing a minor budget item with huge potential like this under the bus in the name of pretending to become fiscally responsible is beyond short-sighted.

Re:Budget Cuts and the JWT

[DisownedSky]

A 64 million dollar cut isn't much at JWST's burn rate. It's not being thrown under the bus at all. In fact, it's eaten all the money intended for other, equally worthy space science mission. Realistically, it isn't going to launch until 2015 at the earliest (my money's on 2016) and will cost much more than it's current massive overrun.

Re:Budget Cuts and the JWT

[dkleinsc]

While I recognize the U.S. is totally fucked, economically, this is a mistake. Throwing a minor budget item with huge potential like this under the bus in the name of pretending to become fiscally responsible is beyond short-sighted.

The reason that's happened is that the US is totally fucked politically as well as economically.

Re:Budget Cuts and the JWT

[Big Smirk]

No problem. They'll just save that money by skipping a few focal length tests on the mirror.... Oh wait...

Re:Budget Cuts and the JWT

[hedwards]

That's what we call being "fiscally conservative." You sign off on massive debt for wars and other pointless silliness even as you cut funding to tiny projects that are likely to lead to prosperity in the future. To put it into perspective, anything that costs less than about $15b isn't worth obsessing a lot over. That's about $1 a week per person for the year, sure it adds up but we're not going broke on that. We're going broke on big budget items like the overspending on the DoD and welfare for billionaires.

Re:Budget Cuts and the JWT

[natehoy]

You could say the same thing about most of the cut items, but the problem is that we can't touch the Holy Trinity (military, tax breaks, and the entitlement programs). The Trinity accounts for too large an amount of the budget for anything else to mean fuck-all to the deficit. Even if you cut pretty much everything but the Trinity, we'd still have a deficit.

Raise taxes across the board, you're a right-wing baby-killer. Raise taxes on the rich, you're a job-killing pinko communist. Cut the military, you're a terrorist-loving peacenik asshole. Assess taxes on Churches, you'll be excommunicated from your cult before you get recalled. etc etc.

Re:Budget Cuts and the JWT

[CrimsonAvenger]

You sign off on massive debt for wars and other pointless silliness even as you cut funding to tiny projects that are likely to lead to prosperity in the future.

I'm really curious as to how the JWT is expected to "lead to prosperity in the future". Off the top of my head, I can't foresee anything meaningful to our standard of living coming from IR pictures of the early universe.

Re:Budget Cuts and the JWT

[Lord Ender]

While I recognize the U.S. is totally fucked, economically

The Federal government is kinda fucked fiscally (though not irrecoverably so), but the U.S. itself is pretty well-off economically. Our unemployment rate is "only" 9% and we have one of the highest median household incomes in the world. Parts of Asia may have lower unemployment at present, but you really need to have everyone working when you make $2000/year on a full-time income.

Re:Budget Cuts and the JWT

[Kiliani]

If I remember correctly, six months ago it was to cost 5 billion dollars ($5,000,000,000) for a 2014 launch date. If the launch slips (and believe me, it will), you can add a couple of $100M (that's several $100,000,000) before all is said and done. Just look at the Mars Science Laboratory rover to learn how it is done. $64M is peanuts when it comes to that.

Re:Budget Cuts and the JWT

[TheTurtlesMoves]

You don't get a extra dollar a year. You get just an extra dollar. Just once....

Re:Budget Cuts and the JWT

[hedwards]

That's the thing, there will be at the very least new technologies required to make this work, and if we do ever send people to colonize Mars, we're going to need to be able to communicate with them, and as such being able to put things in that particular Lagrange point is going to be really helpful to that end.

Re:Budget Cuts and the JWT

[hedwards]

I'm going to call bullshit on that. I doubt very much that anybody thought that Sputnik would lead to so much of modern life, at the time it was mainly a matter of putting an object into space before they could put animals in space so that they could ultimately put a man on the moon. But it's turned out to be essential to much of modern life.

The thing is that most of the innovations coming out of space research aren't thought of as such, battery technology, without which we wouldn't have cell phones or portable computers was driven in large part by space research.

I hope they're building several of these

[PeterM from Berkeley]

I think just having "one" Hubble space telescope was a mistake. I hope they're building more than one of these new 'scopes.

I mean, it'd be a shame if a launch incident destroyed a unique capability. And it shouldn't cost anything like N times as much to build N of these at the same time, right?

--PM

Re:I hope they're building several of these

[Anonymous Coward]

Of course not - the thing is a few billion Dollars to build and not exactly cheap to launch either.

In fact - if it does break, even if just in a minor way (e.g. the solar panels don't unfold because a space flea is jamming a gear), it's likely going to be a multi-billion dollar piece of space junk.
Why? Because it's going to sit at the Lagrange 2 point when it goes operational. That's far, far further than we've put humans (way beyond the Moon), which so far have been the only instruments adapt enough to do repairs on satellites (such as the ones for Hubble).

As it is, the James Webb Space Telescope is awesome - in infrared and -only- infrared. People suggesting it's a -replacement- for Hubble (IR, Visible, UV) are completely and utterly deluded.. or looking for additional grant money. They might as well claim it's a replacement for Chandra (X-Ray) as it's almost equally as idiotic.

Re:I hope they're building several of these

[spacemandave]

Actually, more than a dozen "Hubble space telescopes" were built and launched into orbit. The biggest differences are that they point at the Earth instead of away from it, and they are called KH-11 instead of HST. Oh, and their imagery data is mostly classified.

Re:I hope they're building several of these

[spacemandave]

http://en.wikipedia.org/wiki/KH-11_Kennan

Re:I hope they're building several of these

[DerekLyons]

it shouldn't cost anything like N times as much to build N of these at the same time, right?

It depends on how you calculate N.
 
If you look at the total cost of the satellite (cost to procure the bird + the birds amortized share of the R&D program), then yes - N drops considerably. But that's not really an accurate method of accounting in this instance because you're performing the R&D no matter how many you build.
 
If you define N as the opportunity cost (just the direct costs to procure the bird), then maybe - N does drop, but not as much as you might think.
 
The reason it doesn't drop as much as you might think is the massive amount of man hours devoted to testing, verification, and QA of each component.

Re:I hope they're building several of these

[Chris Burke]

Your point is well taken, so don't take this wrong. It just bothers me how you're using "down" to describe going to smaller wavelengths from IR to visible, which conflicts with meaning of infrared which is "beneath" read just as ultraviolet means "above violet". There's already a pre-defined orientation for the spectrum where lower frequencies is "down". /nitpick :)

Re:I hope they're building several of these

[arisvega]

These things are insured. Yup, there is insurance for space missions- lots of money, but it pays back to have one.

In the unlucky event of an accident, a significant amount of the cost will be returned- sure, they won't launch again on the next day, but it's far better than loosing the craft and the money.

Re:I hope they're building several of these

[skoda]

They're not. Just the one.

Re:I hope they're building several of these

[mhajicek]

But you have to develop the testing methodology and devices to inspect one, why not just run another unit through? Speaking as a manufacturer of medical device components I know from experience that the first part is where a huge percentage of the cost resides. Time and materials to machine a duplicate part once the programming, tooling, and inspection systems are set up and proven would be cheap. You can bet that they make spares (and certify them) for most components just in case something goes wrong and the thing needs to be replaced before launch.

Re:I hope they're building several of these

[DerekLyons]

I know from experience that the first part is where a huge percentage of the cost resides. Time and materials to machine a duplicate part once the programming, tooling, and inspection systems are set up and proven would be cheap.

That's true to some extent, but you still have to test, verify, and QA the new part - and that's where the real costs are in manufacturing a spacecraft. And not only do you do that to each individual part, you do it to assemblies as they are built up, and then to units built of those assemblies, and so on up the chain to complete spacecraft.
 

You can bet that they make spares (and certify them) for most components just in case something goes wrong and the thing needs to be replaced before launch.

For most parts, but by no means all. They stopped building complete backup spacecraft or sparing all components decades ago, it was simply too expensive.

Re:I hope they're building several of these

[Brett Buck]

They are certainly not insured. Commercial spacecraft are usually insured, but not government.

Re:I hope they're building several of these

[TheTurtlesMoves]

For this level of instrumentation, there are no economies of scale. Its why good optics are expensive even for terrestrial applications and with lots of competition. making stuff accurate to +-50nm or so over a large area is expensive.

Re:I hope they're building several of these

[arisvega]

You certainly sound certain- most of that traffic though is commercial, and I can assure you that all projects I've worked with and heard of have been insured.

.. but not government.

Perhaps your statement is correct in the government domain, but where is the line between government and commercial in this case? A big project usually has several contractors involved (the ones that get to handle the data first), in many an occasion each one building an instrument for the observatory that gets a ride along the main "government project", if you will. If one of them was mine, I would make it damn sure to insure it.

Baby pictures? Infrared? Awesome!

[acidradio]

I wonder what would happen if we started taking baby pictures in infrared. Maybe NASA just thought of something that every Sears Portrait Studio should offer.

1. Take baby photos in infrared
2. See stars and other galaxies
3. PROFIT!

Ares and Constellation

[TopSpin]

JWST is great and I'm glad their building it. Prior to canceling Constellation, NASA was investigating this:
http://www.youtube.com/watch?v=2YsNvpVSzbI

It wasn't all about space cowboys. In terms of cosmology, if this had been only thing Ares V had ever accomplished it would have been worth every cent.

Maybe China will get there.

Look at the price tag

[PineGreen]

As a professional astronomer I hoped this thing would never have happened. It costs 6 billion and at this price tag a 5% overrun is $300 million, about six times the cost of the entire SDSS project, which has undoubtedly gave us more science that James Webb ever will. True, Hubble and JWST make great pictures, function as amazing PR machines, but most science at the end of the day comes from survey imaging and spectroscopic observations.

Re:Look at the price tag

[JoeMerchant]

SDSS was good science, making great use of relatively humble tools. But, it takes an ecosystem - and heavyweight instruments like the Webb, or the LHC, will illuminate things that can later be confirmed with the broader toolset of more pedestrian instruments, things that would just be considered a wild theory unless they came with backing from observations on an instrument like the Webb.

You also need to face up to the reality that if the Webb were scrapped at inception, it wouldn't have meant $6B extra would have been supplied to general astronomy, only a small fraction of that money would have made its way around the community.

Re:Look at the price tag

[melikamp]

I totally believe you when you say that surveys provide more and better scientific data, but as a tax-payer I am thrilled with HST's performance, and I could hardly be happier about this wealth of data, which is useful to everyone, professionals and amateurs alike. The only thing I dislike about JWST is that we cannot service it, as so we miss an opportunity to launch more people into space. You guys could turn the surveys into PR machines too, you know. In KStars, for example, there are shortcuts to download DSS and SDSS. I click on the star map and a DSS picture for that place gets pulled. But it could be so much better: DSS is slow to the point of being unusable, and the available SDSS data doesn't seem capture that much of the sky. With a bit of tweaking, I bet we could have a google-map-like app for the surveys to blow everyone's mind, and then you'll see more cash pouring in for these kinds of projects.

Re:Look at the price tag

[DerekLyons]

As a professional astronomer I hoped this thing would never have happened. It costs 6 billion and at this price tag a 5% overrun is $300 million, about six times the cost of the entire SDSS project, which has undoubtedly gave us more science that James Webb ever will.

Science isn't something you can measure by how many buckets you collect. Not all buckets have the same value.
 

True, Hubble and JWST make great pictures, function as amazing PR machines, but most science at the end of the day comes from survey imaging and spectroscopic observations.

If you honestly believe that all Hubble and JWST are doing or will do is collect pretty pictures, you're either hopelessly ignorant or hopelessly biased. But ff you want to talk spectroscopy - consider that four of the Hubble five main instruments are dedicated to spectroscopy, and two of JWST's three main instruments are so dedicated. If you want to talk surveys... Check out Hubble's schedule from Feb 14, 2011, or January 29, 2011 for some recent survey campaigns that Hubble is participating in.

Re:Look at the price tag

[skoda]

JWST has spectroscopy e.g. NIRSPec = Near Infra-Red Spectrophotometer.

The JWST is more about massive light gathering (seeing closer to the dawn of the universe than ever before) than pretty visible-light images.

Re:Look at the price tag

[Ian Paul Freeley]

Yes, if only there were a google-map-like app that had SDSS data in it. I know, they could call it google sky! Oh wait, they did. Personally I prefer wikisky.org.
Step 1. Put survey data on web with a nice interface
Step 2. ?????
Step 3. PROFIT!

Re:Look at the price tag

[melikamp]

Google-sky is not scientific: it has "google" written all over it.

There is no "do over" for James Webb

[Just_Say_Duhhh]

Not that I'm expecting some catastrophic screw-up on the scale of the Hubble, but if there is a problem with the JWST, once it is sitting out at the Earth-sun L2, we won't be able to go visit it and repair it. I haven't heard of any contingency to allow it to come back to earth, so they've really got one shot to get it right.

I'm hoping everything is nominal.

Re:There is no "do over" for James Webb

[skoda]

Actuated primary mirror segments, actuated secondary mirror, and a wavefront sensor system enable it to self-align. While it's much more complicated, and unreachable for servicing, it's also much more flexible for on-orbit self corrections.

Re:There is no "do over" for James Webb

[rcw-home]

Yes there is. Build and launch another one. It should be a heck of a lot cheaper the second time around - most of the money for these things does not pay for the parts.

Re:There is no "do over" for James Webb

[arisvega]

we won't be able to go visit it and repair it.

Why not?

Re:There is no "do over" for James Webb

[Just_Say_Duhhh]

What manned craft do we have that can go out to L2 and back?

That would be MUCH farther than any manned craft has ever traveled. Even if we had a spare Apollo system laying around, even that couldn't get there (and get back - there's no body to slingshot around). I'm not saying it's impossible, but at least with Hubble, we already had something built that could go visit it.

Re:There is no "do over" for James Webb

[arisvega]

It was rhetorical --my bad for not clarifying it

It's just that, you know, about FORTY (40) years ago, the US was apparently just dropping by on the Moon for the weekends, to play golf. One would extrapolate that US spacecraft would be halfway to prox Centauri by now.

La Grange point

[Hatta]

They've got a lot of nice telescopes out there. Haw haw haw haw.

Obligatory

[Takichi]

Obligatory Perry Bible Fellowship reference: Photo Album

I was thinking the same.

[Picass0]

Hubble didn't work out of the box. From the moment it was deployed there was a spacewalk to unfold one of it's solar panels. Then there was a famous 'set of glasses' fix to it's optics. There have been hardware upgrades and gyroscope fixes.

It takes only one small glitch for this to be an expensive piece of space junk. It would kill any future space telescope in the process.

Re:I was thinking the same.

[Grizzley9]

Surely there's a progressive plan in place to test it out in low earth orbit before launching to L2? Make sure it works before sending it beyond our reach. Seems a bit of extra time and effort on that part would be good insurance on a $6B project.

Re:I was thinking the same.

[WaffleMonster]

Hubble didn't work out of the box. From the moment it was deployed there was a spacewalk to unfold one of it's solar panels. Then there was a famous 'set of glasses' fix to it's optics. There have been hardware upgrades and gyroscope fixes. It takes only one small glitch for this to be an expensive piece of space junk

JWST operates mostly in the far infrared where there are a lot more tolerances vs visible light telescopes. The new gyros are a totally different technology... much more reliable - less wear items.

There are ways to hedge complexity with redundancy and testing but there is always risk.. I don't think your sentiment is lost on anyone working this project.

Re:I was thinking the same.

[skoda]

No. Not in the sense that it would sit in Hubble-type orbit for a year while it's tested, and astronauts go to turn wrenches and adjust things that aren't right. And yes, I suspect that would much more than "a bit of extra time and effort." It's probably completely at odds to being launched to L2, and would be an incredible cost and complexity adder.

But it has pre-flight testing and a lengthy in-space verification process as it reaches L2.

The future of telescopes.

[Facegarden]

The real future of telescopes will have no mirrors.

I'm not sure why no one has made a big deal out of this, but superconducting cameras have the potential to completely replace mirrors in telescopes, making them more robust and essentially eliminating complex alignment.

Why do I say this? Well, I reasoned this out myself, so maybe I'm wrong, but basically superconducting cameras are able to register every photon that sees them, sending off ~18000 electrons per photon hit. CCDs, on the other hand, send off 1 electron for every photon hit (I read that a while ago but I think those are the numbers).

Since CCD sensors are so much less sensitive, we use massive mirrors to magnify the amount of light hitting the sensor.

Well, it seems to me that if we had high resolution functional S-CAM sensors, we wouldn't need mirrors. We could just point them straight to the sky, and even if 18000 times fewer photons hit them, they'd have roughly the same or better output as a CCD.

Or, you could just lay out a giant array of S-CAM pixels, say, 10 meters in diameter. Then you'd basically have a ten meter telescope without the mirrors, *and* it would be vastly more sensitive.

I understand that using superconductors is currently an enormous pain in the ass, and I'm not expecting us to find a room-temp one any time soon, but even with the complexities of keeping the sensor cool, wouldn't that have enough advantages over a traditional system that it might be worth it? Maybe not yet, as the sensors currently have to be 0.3K, which seems to me to make it extremely challenging. But if we could make them with something warmer - say, liquid nitrogen cooled - then they might be viable.

Is there any flaw in my basic reasoning? I mean, maybe it would be more expensive than I imagine, but I feel like we should be looking into it. Imagine a football-field sized array of S-CAM sensors. I feel like we could pretty much see license plates on alien worlds at that point. And it wouldn't be nearly as fragile as something with a mirror.

http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=36685

That is the third generation superconducting camera sensor that the ESA is working on. It only has 120 pixels, but I really believe we should be putting way more money into researching these...
-Taylor

Re:The future of telescopes.

[blincoln]

Even with the most sensitive detector possible, you still need a lens to focus the image. Otherwise you've just got a very fancy flatbed scanner, and everything further away than a couple of inches will be a useless blur.

The lens can be virtual, like in synthetic aperture systems, but building something like that for optical wavelengths with literally *no* physical lenses involved (whether those lenses are glass, mirrors, or whatever) on a football-field-sized scale would be challenging at best. Each photosite on each of your supercooled sensors would need to capture phase information as well as amplitude. The system would also have to store timestamps for each pixel with atomic clock-level accuracy in order to use the phase information. I think some day, the human race will build something like that, but it's probably going to be awhile.

Re:The future of telescopes.

[Facegarden]

Even with the most sensitive detector possible, you still need a lens to focus the image. Otherwise you've just got a very fancy flatbed scanner, and everything further away than a couple of inches will be a useless blur.

The lens can be virtual, like in synthetic aperture systems, but building something like that for optical wavelengths with literally *no* physical lenses involved (whether those lenses are glass, mirrors, or whatever) on a football-field-sized scale would be challenging at best. Each photosite on each of your supercooled sensors would need to capture phase information as well as amplitude. The system would also have to store timestamps for each pixel with atomic clock-level accuracy in order to use the phase information. I think some day, the human race will build something like that, but it's probably going to be awhile.

Ah. Yeah, I was wondering about optics.

Well, it would still allow much smaller mirrors to be used, right? So something like a (relatively cheap) 30" mirror with an S-CAM sensor would be able to outperform a much larger telescope with a CCD?

Even if there are optics involved, making the sensor 18000 times more sensitive seems like it would be immensely more helpful than just making bigger optics.

Re:The future of telescopes.

[ogre7299]

You still have to contend with the diffraction limit though, 100% efficiency be damned if you can't resolve anything. Also, CCDs are not as ineffecient as you are purporting them to be; they are as efficient as ~90% at some wavelengths (http://www.astronomy.ohio-state.edu/MDM/MDM4K/qe.jpg); therefore, getting 100% effeciency is not going to increase your signal as significantly as you seem to think.

Re:The future of telescopes.

[ogre7299]

I missed a point here, you seemed to be implying using these for optical interferometry. However, we cannot currently digitize an optical signal and current optical interferometers use analog methods to create interference fringes. At radio wavelengths we can simply downconvert the signal so something more manageable and then calculate the antenna-antenna the interference.

Re:The future of telescopes.

[currently_awake]

A camera needs the light to be focused. You either need a glass lens or a mirror. Without the focus you just get an omnidirectional light detector but no picture.

Re:The future of telescopes.

[skoda]

That's not how optics work. You need to image what you want to see onto your detector.

To test this: remove the lens from your DSLR and take a photo. You'll get nothing but blur.

Re:The future of telescopes.

[Facegarden]

That's not how optics work. You need to image what you want to see onto your detector.

To test this: remove the lens from your DSLR and take a photo. You'll get nothing but blur.

Yeah I was wondering about that. Some of the other replies cleared that up earlier.

I still imagine that investing in those sensors would have a great payoff.

Re:The future of telescopes.

[mhajicek]

Wish I had mod points, don't know why parent got rated zero. He's right, you need something to focus if you want an image, otherwise you'd register every photon from all directions, just like holding old-fashioned camera film out in the light.

Re:The future of telescopes.

[mhajicek]

You should be modded up, not down. Sure you're not giving them the answer they want to hear, but it's the right answer. You should be rewarded for sharing your knowledge, not punished for it. It's like the guy who thought he had a great idea to put wind turbines on an electric car to extend the range. It took me fifteen minutes to convince him he was wrong, and he wasn't happy about it.

Re:The future of telescopes.

[Martin Blank]

don't know why parent got rated zero

Because it's an AC, and ACs start at zero.

Re:The future of telescopes.

[Laser Dan]

Well, it would still allow much smaller mirrors to be used, right? So something like a (relatively cheap) 30" mirror with an S-CAM sensor would be able to outperform a much larger telescope with a CCD?

Even if there are optics involved, making the sensor 18000 times more sensitive seems like it would be immensely more helpful than just making bigger optics.

You need a lens/mirror to focus, but the reason they have to be so big is to collect more light. The problem is not so much that the CCD doesn't detect all of the photons, but that there aren't many photons to detect in the first place! A sensor 18000 times more sensitive can still only detect photons that arrive.

The objects being imaged are reeeally far away, so you want to collect light from as large an area as possible to reduce the exposure time you need. A quick google says that some hubble exposures are 11.3 days long. That gives some idea of how dim the images are.

Re:The future of telescopes.

[laughing_badger]

Well, I reasoned this out myself, so maybe I'm wrong, but basically superconducting cameras are able to register every photon that sees them, sending off ~18000 electrons per photon hit. CCDs, on the other hand, send off 1 electron for every photon hit (I read that a while ago but I think those are the numbers).

Since CCD sensors are so much less sensitive...

Actually, they are equally sensitive. They are both capable of telling us that 1 photon impact occurred. You can't get any more sensitive than that.

Re:The future of telescopes.

[Facegarden]

Well, I reasoned this out myself, so maybe I'm wrong, but basically superconducting cameras are able to register every photon that sees them, sending off ~18000 electrons per photon hit. CCDs, on the other hand, send off 1 electron for every photon hit (I read that a while ago but I think those are the numbers).

Since CCD sensors are so much less sensitive...

Actually, they are equally sensitive. They are both capable of telling us that 1 photon impact occurred. You can't get any more sensitive than that.

Well, while they both technically are capable, I don't think we're currently able to sense the one electron that came off of the CCD, are we? Don't we need many electrons before we can sense them?

Building it is the easy part.

[codepunk]

Building one is the easy part, launching it into orbit is another matter entirely.

Re:Teaser title!

[natehoy]

Meaning no offense, but have you ever actually submitted a story? Titles are limited to 50 characters. It leads to terrible, terrible headlines.

"How Scientists are Building a Telescope That Trumps Hubble!" gets truncated to "How Scientists are Building a Telescope That Trump"

Many of the bad headlines here are actually the result of trying to get something like "How scientists are building a telescope that is superior to Hubble" in a headline field that basically only allows "Science cool! They build'um Hubbleplus Telescope!" (note that, coincidentally, my headline just happens to fit with ZERO extra spaces.)

Re:Golden Snowflake on a Surfboard

[natehoy]

Space is big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the drug store, but that's just peanuts to space.
  - Douglas Adams

DOUBLE ORIGINAL PRICE

[peter303]

$6.5B versus $3.5B. Much of that cost overrun is from being years late.

Are La Grange points safe for satellites?

[GodfatherofSoul]

Seems like a natural gravity pit wouldn't be the best place to hang out.

Re:Are La Grange points safe for satellites?

[AikonMGB]

L1, L2, and L3 are not stable (if you stick a rock there, it will fall away in "no time"). JWST is going to be placed at L2 (though it will move around a bit in a halo orbit). Only L4 and L5 are stable.

Aikon-

Re:Are La Grange points safe for satellites?

[not-my-real-name]

It's my understanding that only L4 and L5 are actually gravitational minima. The other LaGrange points are actually saddles. This means that the point itself isn't stable, but stable orbits around the point do exist.

Re:Are La Grange points safe for satellites?

[codegen]

Its not going to be at the actual L2 point, it is going to orbit the L2 point. True, other objects may also be orbiting the L2 point, but its a little less crowded staying slightly away.

Re:Are La Grange points safe for satellites?

[rcw-home]

The L2 point (which is where JWST is headed) isn't a gravity pit - it's a gravity hill. It's a long-term unstable orbit, but it takes minimal delta-V to stay put there with active correction.

L4 and L5 (60 degrees ahead and behind the orbit of the lighter-mass object) are the gravity pits, and lots of miscellaneous stuff does collect there. But even then, it's still nearly empty space and whatever has collected there isn't moving fast relative to you.

Why such a high orbit?

[sdguero]

I RTFAs and still can't figure out why it has to be further out than the moon to get good pictures. Shouldn't it be able to take nice pics in LEO? Why so far away?

It seems like it'll be next to impossible to fix if anything goes wrong, like it did over and over again with Hubble.

Re:Why such a high orbit?

[AikonMGB]

JWST's optics and sensors have to be kept very cold, something that is difficult to do in LEO thanks to all of the Earth IR and albedo. Putting it at L2 means the Earth's disturbances will be in line with the Sun's, and they can use a single stationary shield to protect the optics and sensors.

But yes, you are right, it will be significantly more difficult (impossible with current technology) to service it.

Aikon-

"trumps Hubble"

[Lemmy Caution]

OK, I have no productive contribution here, but the phrases "Hubble trumping" and "trouble humping" are now echoing through my head.

Re:"trumps Hubble"

[arisvega]

Really? How about "The Large Hardon Collider" ?

I hope they get it right first time this time...

[Rhodri Mawr]

http://en.wikipedia.org/wiki/Hubble_Space_Telescope#Flawed_mirror

With tolerances at the micron level and such a remote location (doubly so, given the forthcoming decommissioning of the Space Shuttles), they'd better get it right first time this time and build in far more redundancy than the Hubble Telescope has. I'm reminded of the opening chapter of Mostly Harmless by Douglas Adams...

Up close and personal...

[ubercam]

I've been lucky enough to have had a peek inside one of the cases (as it was being built and having the kinks ironed out) they're going to use to transport the reflector sail things from the manufacturer to the assembly plant, one case per sail. My friend is the shop's computer guy. The case was enormous and had to be perfectly air tight so it could be filled with nitrogen to protect the sail during transport. I saw it in July so I'm pretty sure they've finished and shipped them all by now.

Granted, it wasn't a component of the actual spacecraft, but an important piece of the puzzle nonetheless. I still think it was very cool to have had the privilege of poking my head inside, snapping a few photos and chatting with the guys making it.

Weird diffraction spikes

[FridayBob]

When astro images are made with reflecting telescopes, diffraction spikes around bright stars can usually be seen at 0, 90, 180 and 270 degrees. Sometimes they are rotates a bit, but most of us are so used to seeing these little crosses, that artists often add them in their renditions of star fields.

This won't be the case with the James Webb Space Telescope, however. Once it begins operations, we're going to have to get used to seeing diffraction spikes around stars in the images it sends back to us at something like 0, 150 and 210 degrees. In short, they will look like little Y's. It will take a little getting used to, but I look forward to seeing them anyway.

Re:Weird diffraction spikes

[tuxicle]

Actually, they'd look like a six-pointed pattern, since the diffraction pattern would always be symmetric. This would be similar to sidelobe patterns on center-fed reflector antennas - the more common three-strut antennas have six cuts where sidelobe levels are higher, four-strut antennas have four cuts. However, the sidelobe levels are higher for four-strut antennas, one way of thinking about it is the energy gets spread out into more cuts. Assuming optical telescopes work in a similar manner, the diffraction spikes from the JWST should not be as bright as those from HST or other reflectors, but there'd be more of them.

Re:Can we see the big bang?

[arisvega]

Nope- the idea is that it expanded at an exponentially increasing speed, far, far, far faster than the speed of light. Look up the theory of inflation for more

The only way I can make this sound as non-sci talk as possible, is to say that space itself expanded. Then again, "expanded" is not exactly the correct word, because we would expand with it and not have a clue. More like, when space expands (and it does so for reasons unknown) then more space is created in between to fill the, uhm, gap.

I don't know man, I didn't do it.

At least I'm pretty sure I didn't.

If you want a comparaison with hubble

[JonySuede]

If you want a comparaison with hubble go there : http://www.jwst.nasa.gov/comparison.html

Am I alone in thinking

[lxs]

That naming the telescope after a NASA administrator is possibly the lamest thing they could have done?

Baseline 6.5m?

[Internetuser1248]

I am a little disappointed to be honest. I was expecting the next generation of telescopes to be multiple components in formation, an array of smaller mirrors covering an area of several kilometers, all reflecting towards a central light collector. The idea of a telescope with a > 1km baseline is very exciting as the resolution it enables would be staggering. A big enough baseline should enable us to resolve individual planets in nearby solar systems.

Oh well, maybe the next generation.

Re:The universe of stars is finite

[juggledean]

As Edgar Allen Poe among others has noted the dark background of the night sky means there are not an infinite number of stars out there.

.

The spiritual universe may be infinite and perhaps the unobservable universe(s) as well.

they can do better

[BusyBeeNYC]

They can do better... I totaly agree with Baseliene 6.5 http://bbcleaningservice.com/Office_Cleaning_Services.html