I am aware that it is not going to happen or even possible but if the dish at arecibo was a mirror instead used in an optical telescope how far would we be able to see? Then how far with gravitational lensing. The record from what I hear is over 14 billion light years with the new Japanese telescope.

---

I am aware that it is not going to happen or even possible but if the dish at arecibo was a mirror instead used in an optical telescope how far would we be able to see? Then how far with gravitational lensing. The record from what I hear is over 14 billion light years with the new Japanese telescope.

the only reason I'm asking is because I read an article about a spherical universe and was wondering if that is a theory that could be proven using an extremely large telescope. Is it at all possible to make a mirror that big?

---

I am aware that it is not going to happen or even possible but if the dish at arecibo was a mirror instead used in an optical telescope how far would we be able to see? Then how far with gravitational lensing. The record from what I hear is over 14 billion light years with the new Japanese telescope.

the only reason I'm asking is because I read an article about a spherical universe and was wondering if that is a theory that could be proven using an extremely large telescope. Is it at all possible to make a mirror that big?

Yes, using the multiple mirror technique pioneered by prof. Guido Horn d'Arturo of Bologna Astronomical Observatory in the Forties. Today it is a standard technique in the big observatories.
Tullio

---

Then how far with gravitational lensing. The record from what I hear is over 14 billion light years with the new Japanese telescope.

Are you sure about that number?

Since the universe is estimated to be roughly ~13.7 billion years old, and the early universe produced no visible light, I'm not sure how it would be possible to see over 14 billion light years...

Then how far with gravitational lensing. The record from what I hear is over 14 billion light years with the new Japanese telescope.

Are you sure about that number?

Since the universe is estimated to be roughly ~13.7 billion years old, and the early universe produced no visible light, I'm not sure how it would be possible to see over 14 billion light years...

Those estimates are VERY general. It's very hard to estimate how far are the furthest objects (i.e., quasars) since they're ... very far away. From what I've heard from various astrophysicists the age might be somewhere between 12 and 17 bn. It's very hard to determine the Hubble constant (which is neccessary for calculating the age of the universe) - I think that it's now aroung 50% of its first value. Remember: every constant is variable. ;)

---

"Failure is not an option."
Gene Kranz, Apollo 13 Flight Director

"Be the change you want to see in the World"
Mahatma Gandhi

My web-page:
www.dywanik.eu

The April 2008 issue of Sky and Telescope magazine has an article by Jonathan Lowe about plans for giant optical telescopes. The biggest I see there is the European Extremely Large Telescope that will have 907 hexagonal mirrors and an aperture of 42 meters. First light is expected in 2017. It would be worthwhile to read that six-page, illustration-packed article.

---

The April 2008 issue of Sky and Telescope magazine has an article by Jonathan Lowe about plans for giant optical telescopes. The biggest I see there is the European Extremely Large Telescope that will have 907 hexagonal mirrors and an aperture of 42 meters. First light is expected in 2017. It would be worthwhile to read that six-page, illustration-packed article.

It's worth noting that the telescope was supposed to have aperture of 100 m but it was to expensive. They say the next one will do. ^_^

---

"Failure is not an option."
Gene Kranz, Apollo 13 Flight Director

"Be the change you want to see in the World"
Mahatma Gandhi

My web-page:
www.dywanik.eu