Why cant we build a telescope that can see twice as far as the hubble.
I'll butt in to save Eta a bit of time. His time is more valuable than mine.
You have to be careful with the "twice as far". The Hubble already sees back more than half way to the big bang (much more than half way) so nothing can see "twice as far".
We can, however, build a telescope that can see twice as clearly at a given distance or pick up things twice as faint. The only thing stopping that right now is money. A few billion would build a much more powerful instrument and I'd pay my share of extra taxes to cover it at the drop of a hat given what Hubble has shown us.