Now that the latest series of Doctor Who has finished it is maybe time to discuss the central theme of the series – time travel. Does science show any indication that it may be possible?
Theories do exist – and significantly more advanced than the Doctor’s understanding of ‘Timey Whimey.’ But what is time? The physicist, Wheeler, put it well when he said: ‘… time is what keeps everything from happening at once.’
WHAT IS TIME?
Time, though, is hard to grasp. For instance, we can identify periods of time in the revolution of the Earth (a day), or the time it takes the Earth to orbit the Sun (a year). But other than this, time is without known units.
The units we know of – seconds, minutes, hours, etc – are a product of mathematics, slicing the known, astronomical time periods into bits so we can manage our lives. In this sense, time is something we impose on ourselves.
A more grounded explanation of time is to say it is a process we must experience because things happen in time – in particular, a process that reduces things to chaos – from order to disorder. This is decay, erosion – basically, entropy.
ARE WE STUCK IN TIME?
Time seems to have a fundamental effect upon us. Indeed, we live our own ‘time-line’, which merges with other’s to produce the onward progression of ‘us’ IN time. It has to be like this or our experiences would be nonsensical.
This is due to the Law of Causality. Basically, this says that a cause must come before an effect. For instance, a bullet must be fired (a cause) before it can hit someone (an effect). To be any different would be ridiculous.
This is reflected in the Newtonian view of space and time as mechanistic, unchanging, absolute. Here, time is the inevitability of an easily understood ‘machine-like’ universe. Unfortunately, though, the universe isn’t like that.
RELATIVELY SPEAKING
Einstein destroyed the simplicity of the Newtonian universe with relativity theory. Time was combined with the three known physical dimensions to become a concept known as ‘spacetime’. Things happen physically, AND in time.
Matter and energy can stretch and distort the physical dimensions, so can also have an effect on time. Indeed, time can slow down dependent upon the speed of the observer. This takes away a direct point of reference for a definite time.
In a relativistic universe, time can be different to the situations of different observers. But sadly, one thing remains constant. There is still an arrow of time that points forwards. It never seems to point backwards – in the universe, at least.
WHAT IS NOW?
We think of time in terms of a past, present and future. The past has happened, the present is ‘now’, and the future is yet to happen. Yet whilst it is true to say the future hasn’t happened, the term ‘now’ is far more complicated.
We sense things because forces bombard our sensory receptors. For instance, we ‘see’ because light bounces off objects and thus hits our eyes. But forces take ‘time’ to cross from one place to another.
Due to this, our understanding of a sensory ‘now’ is really a myriad of impressions from different points in the past. Think of a thunderstorm where we see the flash before we hear the bang. This is because light travels faster than sound.
POSSIBILITIES OF TIME TRAVEL
In this sense, our ‘now’ can be a form of time machine. For instance, when we look into space we see the distant past. When we are told we are looking at an object 50 light years away, it is also how it was 50 light years in the past, for it takes 50 light years for the rebounded light to reach us.
The universe holds possibilities of time travel in other ways. For instance, as matter enters a Black Hole, space is said to collapse. As time is as one with space, then theoretically so could time. Hence, if we could access a Black Hole and come out the other end, time travel could have been achieved.
Theoretical particles known as ‘tachyons’ have also been envisaged. Relativity theory says we cannot go faster than light as we would escape the confines of the universe – possibly even go back in time. Tachyons are ‘faster than light’ particles, so, if they exist, they could hold the key to time travel.
SUBATOMIC TIME
Whilst the universe we experience requires an arrow of time, the subatomic world has been observed to be different. There appears to be no observable sense of time in their interaction. So if they are ‘timeless’, could the key lie here?
To many physicists, ‘particles’ are old hat, replaced by a concept known as ‘string theory.’ Here, what we think of as particles are just the ‘ends’ of far more complicated structures.
If ‘strings’ exist as the fabric of the universe, further dimensions are required to make the math fit. The beauty of this is that it holds the possibility of other dimensions of time. So maybe we experience the arrow of time in our known dimension of time alone. Accessing other time dimensions could be the key to time travel.
FUTURE TRAVEL
Most of the theories so far hold a limitation. They deal with time travel in terms of going back in time. Going forward in time is a different proposition – especially if it hasn’t happened.
If, somewhere, it has happened then we face the problem of ‘free will’. If a future is mapped out, how can we have choice to do as we want? Surely a future implies that the decision is already made?
We can counter this problem by viewing the subatomic world – or other dimensions of time – as an eternal now. In such a concept, our choices will continually re-write the script of the future. Perhaps this is what a ‘time line’ really implies. It would provide a future based on our choices at the point when time travel began.
INFORMATION UNIVERSE
The problem with all this is, of course, we are too large to ‘travel’ in a subatomic world. However, there is an argument that the subatomic is, infact, a part of an information universe. We are information within it, so if we could be reduced to information, and reconstructed in the future, we can do it.
Another argument holds that, at an information level, the particle and the universe are one and the same. The particle accesses all the information of the whole. Hence, simply connecting with such a world would display all time before us.
Alternatively, perhaps a future time machine would simply access the timeless information of the universe and portray it in virtual reality. In this concept, we don’t travel in time. Time comes to us.
IN CONCLUSION
At this point in time, time travel appears impossible. But this is maybe a problem of technology alone. Ideas exist that could allow time travel to become a reality. So maybe we will one day become Time Lords with our own TARDIS with which to explore.
For now, it is merely theory. But hopefully, this post will have made you think – if, of course, you have the time.
© Anthony North, July 2007
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