Expert: Tom Whiting - 12/3/2009

Question
Hi!

For the longest time I have been confused on whether or not our current telescope technology allow us to see stars (or other objects) in space at their current state. What I mean is that if light from a particular star takes 4.3 light years to reach Earth. Then we see that object as it were 4.3 years ago. But does our current technology actually allow us to see what the object (i.e. a star 4.3 light years away) looks like at the very moment or instance it is being observed by a telescope?

Thank You!  

Answer
Hi Fawaz,
Of course not.
That's not a technological problem "to solve"... but simply a hard physical law because nothing can exceed light speed. If I'm standing 3 meters from you, you still are not seeing me...right now.  It takes light time to travel even that short distance, so you are seeing
me say, one nanosecond later. There is no physical law that would allow the light to travel
instantaneously. In the same instance, if you are observing Alpha Centauri at 4.3 ly distant,
there is no physical way to increase the speed of the arriving photons. And even a spacecraft
orbiting that star, can only transmit pictures at light speed (no matter what part of the electromagnetic spectrum you want to use), so it does no good to send a spacecraft there either. That's just the physical reality of our Universe, just like an apple falling downward from a tree. It takes time to fall.  Even if they discovered something faster than light (tachyons have been proposed in science fiction movies) and a device to receive them, then the super-light tachyons would have to be traveling backward in time, so even then the information you're receiving...would be 'late' information, not, as you say, "current" information.
But I think tachyons are all science fiction anyway.
The only way to do that in the far far future is to shorten the distance by curving or warping
space itself. If some highly advanced technological civilization could curve or fold the space
between the Earth and say, Alpha Centauri, to shorten the distance, then the time factor could be shortened also...but not down to zero time.  IF warping of space is even possible... right
now that is still science fiction too.
Clear Skies,
Tom Whiting
Erie, PA USA

FOLLOW UP:
Thank your lucky stars that light (and heat, UV, X-rays, etc) aren't instantaneous travelers.
We could never learn the various distances to various objects.
And we all be dead anyway, as we'd have the instantaneous light and heat from the Big
Bang right next door to us (as would every other place in the Universe)...so there would
be no Universe as we know it, IF the electromagnetic spectrum traveled...instantly.
The Universe could not have cooled down (by expansion) from Big Bang if light and heat were instantly present all the time, at every location.
tom