Wednesday, 17 February 2016

M101, the Pinwheel Galaxy and a little Relativity

There are at least 100 billion galaxies in the known universe. Imagine that! Some are smaller than our Milky Way, which is roughly 100.000 lightyears across, but many are much bigger such as Andromeda. The largest we know so far is designated as IC1101 and scientists believe that its size is a whopping 5,8 million lightyears across and that it contains at least 100 trillion stars (compared to 100 billion in our Milky Way). Now imagine that there are an estimated 17 billion Earth-like planets in our Milky Way alone and you'll certainly agree with me that there must be millions of other forms of (intelligent) life out there. Actually, some scientists are no longer asking themselves if there has been or still is life on Mars, but when we'll discover undisputable proof of it. Also Europa, one of Jupiter's moons, and Enceladus, one of Saturn's, seem to be highly probably candidates for extraterrestrial life. Of course, we shouldn't start the whole Roswell flying saucer hysteria all over again, or at least not for the time being. If there's life on other places in our solar system it's almost certainly quite primitive, such as bacteria or other micro organisms. But then again, if there's life, either intelligent or primitive, on even more than one planet in this tiny little solar system, how big are the chances that there are more forms of life out there in the universe than we can possibly imagine? 

Unfortunately, even if we do discover a star with a planet containing intelligent life, it's not going to be an easy conversation, as Carl Sagan perfectly described in his novel 'Contact' (cfr. also the film with Jodie Foster). Suppose that that star's 50 lightyears away from us, which still isn't our backyard but rather the terrace around our house in stellar terms. Then it would take our message 50 years to arrive! And what's more, we'd have to wait yet another 50 years in order to receive their reply! If we then consider that exceeding the speed of light is mathematically impossible (unless Einstein was completely wrong) and that in order to create a wormhole  shortcut through our universe (supposing that this theory is correct) we'd need an energy source at least the size of Jupiter, it's not that we can embark on an interstellar holiday cruise already tomorrow. And to stray completely from my chosen topic for this post, even if we were be able to take that cruise, it'd not be a merry homecoming since the Earth may have aged centuries in the meantime whereas to us the cruise only lasted a couple of weeks. Ah... relativity... the universe is all about relativity and about how incredibly insignificant we humans are, even though some still believe in their arrogance that we're the 'centre of creation', or whatever that may mean. Looking up at the night's sky instead of keeping your nose stuck in a dusty old book nobody knows for sure who wrote it anyway certainly teaches you to put things into perspective. 

To illustrate all of this, I've chosen this sketch of M101, nicknamed the Pinwheel galaxy due to its obvious spiral shape. It's also comparable in size to our Milky Way and therefore it gives us a very good idea of how our galaxy might appear to an inhabitant of the Pinwheel. Although it seems to be much more active than ours and numerous incredibly large stellar forming regions have already been discovered within it. It's not really visible on this drawing but the galaxy's slightly deformed due to gravitational interaction with its 5 major companions, all of which are quite smaller than the prominent galaxy of their group. It lies 21 million lightyears away, almost ten times as much as Andromeda! Or in other words, we see this galaxy as it was when North and South America were still separated, India had only recently begun crushing into the Eurasian plate (forming the Himalayan) and the first ape-like primates appeared. And this is still close by! How about that for relativity? 

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