giant telescope?

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Ok, I have a feeling this may be a dumb question, but here goes:
If bigger telescopes can see farther, why doesn't someone make a huge telescope? One that is 10x or even 100x bigger than the largest one that currently exists? Is there a limit to how large a telescope can be?

Where would they make the lenses and/or mirrors?

http://en.wikipedia.org/wiki/Arecibo_Observatory

At 1000ft/305m the Arecibo radio telescope is pretty big.

Optical telescopes are limited by the atmosphere—it is still a very expensive endeavor to put a big telescope in Space.

http://www.astronomynotes.com/telescop/s11.htm

We don't need bigger telescopes, we need more space telescopes.

The limiting factors are cost and physical limitations. You might notice that most newer giant observatory telescopes today are built with segmented mirrors. There are two reasons for this. One is that because the material the mirrors are made out of tend to be heavy and will ultimately warp under their own weight if they become too heavy. Mirror segments are easier to produce and handle than one large mirror and the smaller size of the segments mean warping due to weight is not as much of a problem. Since the mirrors are segmented, they can be adjusted independently, which is a must for ground based adaptive optics systems. These systems mitigate atmospheric turbulence and have been able to produce ground based images as sharp as images produced by the in orbit Hubble Space Telescope. Without these systems most deep space objects just look like fuzzy glowing blobs.

The largest ground based telescope is currently the Gran Telescopio Canarias with an estimated cost of about $180 million dollars.

Another issue in building large telescopes is they usually need to be placed on mountain tops where the air is thin and dry, in areas where the sky is dark at night and the weather is usually clear. A large segment of ground space can be hard to come by if you wanted to increased the size of the telescope by 10 or 100 times.

It's actually better to have an array of smaller telescopes to make use of a property called interferometry. This is where two telescopes situated in close proximity to eachother are pointed at the same object. Their slightly different viewing angles collect more information on the object, yielding a higher resolution image. This is similar to the concept of binocular vision. Look at an object with both eyes, then close one eye, then open it again. You get a better sense of the object with both eyes.

But the limiting factor is cost, to answer your question.

interferometers is the way of the future, i cant wait for the first space based systems to go online, an intererometer it is the relative distance and the diameter that determine the level of detail.

on earth one of the most impressive interferometers for optical observation is the W. M. Keck observatory, employing 2 mirrors with a diamter of 10m

Yes . A single mirror will bend under its own weight and distort the images. The best that can be done is to build mirrors as segments and even then there is a weight limit. The only way to get Really Big mirrors is to combine them in an interferometer. And even then there is a limit on earth's surface. The shape of the earth is constantly affected by tectonic forces and there is only so much that can be done to compensate for them. The best way to build a composite telescope is to place multiple reflectors in orbit where there is 0 effective gravitational distortion.

ruveyn

Quantum telescopes can see into the future.

Nonsense. Telescopes see into the past.

And what is a "quantum telescope"?

ruveyn

If one were ignorant about the speed of light the concept of a telescope that sees into the past would seem like nonsense.

You still have not said what a quantum telescope is.

ruveyn

What do you think a quantum telescope is?

I have not the foggiest idea. You were the one who mentioned it.

ruveyn

Perhaps NASA should turn its attention to building a huge new space telescope, now that it has ended its shuttle missions?
Though I suppose we'd have no way to get it up there. Funny but actually sad.

Large aperature interferometers orbiting in space are on the drawing board. The only question is: will they be funded?

ruveyn

Have you heard of the James Webb Space Telescope?
it is an IR telescope currently being built. the only problem is that the funding might stop, so if you are a citizen of the USA, please do something to help keep it going!

It is quite amazing what can be achieved these days. the biggest telescopes on earth are now just as good as HST thanks to adaptive optics, so visible light isn't so much of an issue.
The JWST is very important though. it must go up because our atmosphere glows in IR, so IR telescopes can't work on earth.