How far have scientists seen into space?

Using the Hubble Space Telescope we have seen 13 billion light years into space, these are some of the very first galaxies to form after the big bang. [Search for "hubble space telescope ultra deep field images" to see the actual images.]

Although technology is always improving, we can never see much further than this point in time.

The problem is the time it takes for light to travel to Earth. The light we see from these very first galaxies have been travelling for 13 billion years to reach us, so really we are looking back in time. In them 13 billion years the light has been travelling to us, the universe has already expanded another 13 billion years. The reality is that many of the stars that make up these galaxies no longer exist in the same way we are seeing them today.

Theoretically, if the edge of the universe emitted visible light and stopped expanding today, we would still have to wait 13.7 billion years (the current age of the universe) before we would be able to notice. Therefore how far we can see is always governed by the time it takes for light to reach us.

If you think about it - the light we see from these very first galaxies was emitted before life and the Earth even existed! Bare in mind that light travels so fast it could go around the Earth 7 times in 1 second...