Thursday, January 10, 2013
Have you ever looked into the past?
Try this. Ask one of your young children (or your neighbors, if you don't have any of your own) "Can you see into the past?" The last time I asked this question I got a 12 year old doing facial contortions while trying to unravel the syntax of my 'trick' question.
The problem was: it was not a trick question. It was not from a Jules Verne novel or Isaac Asimov's scifi mind. It was not a question from a movie script. And it had nothing to do with time machines.
Can we see into the past?
The answer will surprise you. You see the past every day and every night, and more of it at night.
Here is how: When I get up, draw the drapes, look up into the sky and see our wonderful blazing sun - I am seeing the past.
In fact, I am looking at the sun as it was 8 minutes and 20 seconds ago! That is how long it takes sunlight to reach us on Earth. When I see the sun, in effect I am looking at the sun as it was over 8 minutes - not as it is now. It takes a moment to take this in and understand that we actually see the past all the time.
At night, when the sky is ablaze with the stars and the galaxies - we can see even further into the past. If you look for the nearest star which is Proxima Centauri, a red dwarf star, it is located at a distance of 4.2 light-years away from Earth.
A light year is the distance light travels in a single year – 9,460,528,000,000 kilometers. So the light we see coming from Proxima Centauri left the star 4.2 years ago! If you see it, you are looking over 4 years into the past.
The nearest Galaxy to our own is the Canis Major Dwarf galaxy, which was discovered only in 2003, and is located about 25,000 light years from our solar system. If you could see it, (it isn't very easy since it is a 'dwarf' galaxy on the other side of the Milky Way, which is our galaxy) - you would be looking 25,000 years into the past!
What if you had a telescope? A really powerful telescope. Could you see further back in time. Indeed you could.
Today, astronomers have spotted the most distant supernova ever seen. It is nicknamed "Mingus", and it was described at the 221st American Astronomical Society meeting in the US in January 2013.
It is ten billion light-years distant. Want to see 10 billion years into the past? Take a peek: http://www.bbc.co.uk/news/science-environment-20968199. Mingus will help shed light on so-called dark energy, the force that appears to be speeding up cosmic expansion.
Time, as we know it, began about 13.75 billion years ago after what is commonly called the "Big Bang".
NASA believes it has found the most distant galaxy observed to date. MACS0647-JD is just a fraction of the size of the Milky Way and is believed to be 13.3 billion light years away. (http://www.tomshardware.com/news/space-nasa-galaxy,19149.html).
So if you had the right equipment, not only could you see into the distant past - you could see billions of years into the past. What you see, may not even be there anymore!
Not only can we see the past, but we can see almost to the beginning of time. In this moment, you can see all of elapsed time!