Looking back in Time

Hi,

Most of us might wonder that i will be talking here about some sort of Time Machine to travel back in time but i guess not....From the time Galileo started to use the telescope for taking astronomical observations the world for the first time started to look back in time. Now you might be wondering so Galileo can take the credit for inventing the telescope, but i am sorry its not he who invented it but apparently a person named Hans Lipperhey invented the telescope. He was born in Wesel, Germany.He was a spectacle-maker by trade. But Galileo gets the credit to start using the telescope for Astronomical observations.

So i am cutting the chase and getting to the point now...I just a little background might help to get settled in the topic.So now you might wonder how would it be possible to look back in time with the help of telescope. But i will tell you that you will be equally surprised when i tell you that you can look back in time using your own eyes without any instruments...Sounds interesting yeah i surely grabbed your attention.

You all might have heard in your physics classes that photon is the fastest particle in the universe. So as light is made up of Photons we can say the speed of light is faster than any other known entity. As per the above statements the Universe has a speed barrier and that's the speed of light. You all know that we see things based on the light that comes from those objects. So we see Sun or any other celestial object when the light from them falls on our eyes.

Lets start with some constant values here.....

a)Speed of light is 299,792,458 metres per second (m/s) or 313000 kilometres per second or 186285 miles per second.

b)Time taken by light to reach Earth from Sun is 8 minutes 32 seconds.

c)Time taken by light to reach Earth from nearest star besides our Sun which
apparently is a star 4.24 light-years.

I don't want to confuse you with the light year concept, simply put a light year is the amount of distance travelled by light in a year. So you might wanna pull your pencils and calculate the distance hmmmm its gonna be a big number......

You already know how much distance light travels in a second and you can calculate the number of seconds in a year, multiplying both of them you can get the value of 1 Light year.

313000 km/sec * 31,536,000 seconds/year = 9,870,768,000,000 km/year. (Quite a big number huh)

So i wanna come out of the calculations now and continue our discussion. Now that you know light takes time to reach us from distant objects you clearly can understand when i say that you are not seeing what it is but you are seeing how it was some time back.....

Lets take Sun for example...When you are seeing our Sun the light from Sun travelled around 8 minutes (approximated for clarity) to reach us bringing us the picture of the Sun when it was 8 minutes old. So by this you can be sure that you are only looking at Sun how it was 8 minutes back irrespective of when you see.

So the same thing for any other celestial object, I say celestial objects because the amount of distance that objects on Earth are located are very small when we compare with the vastness of the space where these celestial objects are located from us.

When you look at our nearest star (other than Sun) you are looking at it how it was 4.24 years back but not now. So if there was an explosion of that star you would probably able to see that explosion after 4.24 years (when the light from that explosion travels all the way to Earth).

I guess i made a little bit contribution in helping you all understand what the term looking back in time is with my description with a little humour.

So i guess you wont be surprised any more if you hear that scientists were able to see the early stages in Big Bang.In fact the point is considering that Big Bang happened 10 billion years ago if any technically advanced telescope can locate an object around 10 billion light years away from us we say we hit a jackpot as the light took 10 billion years and that coincides with the happening of the Big Bang and we can be sure that those are the early stages that we are looking at.


FYI - when i say speed of light you need to take into consideration that speed of light in vacuum and not in any other medium.