Recently I visited the Rose Center for Earth and Space in the American Museum of Natural History in New York. Even more recently I saw an IMAX 3D movie called the “Hubble Space Telescope”. These two events/experiences sparked my hitherto dormant interest in the universe, cosmos and astronomy in general. I wanted to read more about celestial bodies and their origins. I did manage to read a little bit. The more I read the more confused I became. I think this is a never-ending mystery. There are many hypothesis and theories about how it all started including the most famous and believed theory – The Big Bang theory. But again these are all just theories with many questions still unanswered. The problem with anything dealing with the universe is the sheer scale and size of the universe. Just think about its massiveness to fully comprehend the problem. Let me give you a brief idea. The part of the universe which is observable from earth (a.k.a – the Observable universe) i.e. the part of the universe from where light rays or other radiations have reached earth so far is ~100 billion light years (i.e. ~10^25 meters) in diameter. It is widely believed today that the universe was formed about 13 billion years ago. Since then light started traveling from the farthest point from earth towards earth and then due to the continuous rapid expansion of the universe, today the edge of the observable universe is about 50 billion light years away from us. We have no idea what lies beyond that. There is a theory which hypothesizes that this is only one of the many universes – the Multiverse theory. They consider it as a multiple soap bubbles with each bubble having different spatial and temporal properties and hence different laws governing them.
Now what are the challenges with such gigantic scales? Even with the fastest possible speed, i.e. at the speed of light, which travels 3oo,ooo kilometers in a second, the universe is just way too big to cover. So, say we create a super strong laser beam and send it to our nearest neighboring galaxy the Andromeda galaxy assuming that it will be reflected back from there and then we will be able to get some useful information out of it, this journey of the laser beam will take only 5 million earth years. In other words had the dinosaurs sent such a laser beam we would be receiving it now! i.e. when light comes back from our neighbor to us, we won’t be here any more to receive and study it. And that’s only for our nearest neighbors. I hope you see the challenge in exploring the universe and finding the truth behind it all?
So what do we do? The only option is to study the radiations which we receive from various celestial bodies to know about their origin and about the galaxies, stars, planets etc. With the help of the Hubble Space telescope and other powerful space telescopes we have been able to capture radiations and to create images of a large part of the observable universe. But there lies another challenge. Our view into the universe is not a present view rather we are looking into distant past. Confused? Well lets say we are looking at the image of a star X which is say 5 billion light years away from us. The light rays would have taken 5 billion earth years to reach us from X. So, the images we are seeing are actually images of the star – 5 billion years ago. Who knows what happened to the star in those 5 billion years? May be in those 5 billion years life originated in star X or on one of its planets -Y, just like it did on Earth. But, we will never know. Because by the time the images of life on planet Y of star X reaches us, we may not be here…our planet may cease to exist!
I had never thought about these problems before visiting the Rose Center in New York. We must ponder over these at least once in a while, though we may not conclude anything other than may be getting more confused than ever. In the rose center they have created something called a Cosmic Pathway – it is a gently sloping 360-foot walkway that leads you on an exploration of 13 billion years of cosmic evolution. It winds one and one-half times around the Hayden Sphere in the Rose Center for Earth and Space.
The Cosmic Pathway illustrates the development of our universe, using a range of media. At the start of the walkway, children and adults alike can measure the length of their stride and determine how many millions of years pass with each step — an average stride covers 75 million years of cosmic evolution. Recorded human history is just 10,000 years old. That is just 1/10000th of the last step on the cosmic pathway. All our existence, wars, cultures, developments, discoveries, everything that we have done so far on earth is just a tiny spot on the history of universe. A walk down the cosmic pathway is thought provoking and it provides perspective to our minuscule existence. We are not even a drop in the unending ocean of matter, energy and space-time.
How did this all begin? This one question has haunted us since mankind learnt to think. But there is no answer to this and I think we won’t be able to answer this ever. We are too small in the scheme of things. Our view of the universe is like what the Pacific Ocean might appear to an amoeba living in the gut of a blue whale swimming in the pacific ocean. That blue whale is our milky way and the pacific ocean is our observable universe. Yes, we are much more informed than that amoeba but even with all these information we just cannot imagine and fathom the complete picture. The picture is so huge and so big that even our wildest and bravest imagination cannot completely capture it. What we can do and what we are doing is to capture tiny parts of it and assume that the laws which are true for these tiny parts will hold good for the entire picture. That need not happen.We won’t ever be able to conduct any experiment which validates our assumptions over the entire space-time continuum. Does it mean we may never know where we came from? I think so.
A more interesting question is – Is there any body else out there? Are we the only planet with life or do we have neighbors, however far they might be? Let’s think logically. There are 100 billion stars in our own galaxy – the Milky way. There are approximately 100 billion similar galaxies in the observable universe. What is the probability that life sustains only on one planet – Earth, of one star – Sun, out of the 10^21 odd stars in the observable universe? This just can’t be. I know that there are factors like water, oxygen, ozone layer etc. etc. which make life sustainable on earth. But why won’t such conditions exist in trillions of other planets? After all it all started from the same elements – hydrogen and helium. So life does exist or would have existed in some form some where else too. The possibility of that not happening is just too improbable and I believe is just giving too much special status to Earth. We may never know that owing to the mammoth celestial distances. But we as mankind must keep trying to find someone, something with life in this ocean of lifeless nebula of gases. Even an iota of evidence will be worth all our efforts.
Here is a real image to give you some graphical sense of the celestial scales. This is the celebrated image of Hubble ultra deep field made possible by the Hubble Space telescope. When you see this image on the IMAX screen with your 3D glasses on – well thats a different view altogether.The bright spots of lights that you see in the image are clusters of distant galaxies – each with their bevy of stars – each with their own system of planets.
If you have some time watch this brilliant video which shows us our real position in this universe. Are we the masters of the universe? I don’t think so. This is posted on the website of American Museum of Natural History. This surely gives us a perspective of the size of the observable or known universe or the “Brahmand” as our Hindu philosophy puts it.
I strongly recommend the Hubble Space telescope movie if possible in an IMAX theater. And if you visit New York, do visit the Rose center and take a stroll down the celestial pathway. I am sure you will feel humble and our existence will seem tiny if not meaningless.
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