It was with some dismay that I read about the discovery of gravitational waves a few days ago. You may ask why, and it would be an entirely reasonable question. After all, this is claimed to be one of the greatest scientific discoveries in living memory, one that apparently cements at least part of our understanding of how the universe works. Therefore, it must surely be a good thing.
The problem is, I don’t like where this is all heading and let me explain why. I have more than a passing interest in the universe. It is, after all, my home on a certain level. There are other places of course, Earth, the United Kingdom and my house, all of which can be classified as my home, but on different levels. I share my house with very few selected people. I share the United Kingdom with around 70 million others. I share Earth with around 7 billion others. These are all measurable facts and the fact that these facts are measurable allows me to put my existence into perspective, to at least a certain extent. When it comes to the universe however, things get a little trickier. It is, for a start, so incredibly and mind-bogglingly big.
We can apparently detect light that started its journey to us 13.8 billion years ago. That is a long time. During that time this light has been travelling at ….er…. the speed of light which is 300,000 kilometres or around 186,000 miles per second. PER SECOND!!! So it has, and this is a mild understatement, travelled a long way in that time, a distance that is described in astronomical terms (and mainly to avoid an inevitable world shortage of zeros) as 13.8 billion light years (1 light year is the distance that light can travel in a year). 1 light year is a staggering distance in itself and we are talking about 13.8 billion of them.
So we can see light that is 13.8 billion years old. Before you get too comfortable with that, keep in mind that we are not talking about the size of the universe here. Oh no, this figure of 13.8 billion light years is only the size of the ‘observable’ universe. There is a lot more out there that we cannot even observe yet, even if what we see is effectively 13.8 billion years old. It seems quite unlikely that anyone can realistically estimate the size of the universe with any reasonable accuracy and indeed it is sometimes suggested that the universe is indeed infinite. Whatever that means.
Apart from the sheer size of the universe, or perhaps because of it, the other problem is that I cannot know, with any degree of confidence the number of other people/aliens that I share it with. At present my best estimate of this number is roughly 7 billion (the inhabitants of Earth) as we have not yet discovered any life elsewhere. With the universe being so big and with it containing billions of galaxies, each with billions of solar systems, one would think that statistically the likelihood of Earth being the only planet supporting life would be infinitesimally small. But however small that probability is the fact remains that doubts will still justifiably remain until we have proof that we are not alone.
Now, back to gravitational waves. They are big news because their discovery means that their mathematically derived existence from Einstein’s work on relativity has now been proved. That part at least is no longer a theory but a measurable fact. It means that a part of Einstein’s work is no longer open to speculation but has to be accepted. Einstein was right about gravitational waves. Einstein was also apparently right about relativity, since although much of this has yet to be conclusively proved it has generally been accepted and it would seem only a matter of time before relativity is granted the status of law rather than theory. That is why I hate Einstein – he is always bloody right.
If Einstein is right about gravitational waves, and if he is right about relativity, then a pattern appears to emerge. He was undoubtedly a genius and therefore the chances are that he was also right about his very famous equation for the relationship between mass and energy, e = mc2. I will not bore you with the mathematical basis of the implications of this equation, but suffice to say it demonstrates that as an object moves faster its mass increases and therefore the energy needed to make it go even faster also increases. This reaches the point where, at the speed of light, the mass of the object becomes infinite and the energy needed matches that. Which is impossible. Which means that travelling at light speed for anything other than light is also impossible. Which brings me back to the universe and my particular need to prove the existence of life elsewhere. How are we ever going to do this?
Any other life in the universe will be so far away that in order to discover it and prove its existence we would need to travel at many times the speed of light, and we now know that we cannot even travel at the speed of light. The same is true the other way around. However much more advanced than us other lifeforms may be, they will also be bound by the same physical limitation on speed of travel, so we cannot travel them and they cannot travel to us. Thanks to Einstein we cannot even dream that this may one day be possible. Despite what we see in science fiction movies and TV shows, however technologically advanced any species may be, the one thing that neither they nor us can escape is that you really cannot change the laws of physics.