part0078

I must certainly be nuts to devote a whole section of this book to the idea of travelling, or potentially travelling, faster than light. There can be few subjects more likely to raise the hackles of your average modern-day physicist. Also, I don’t wish to be seen as trying to contradict the great physicist Einstein, or to be setting at nought the accepted wisdom of the scientific community for the last one hundred-odd years. So let me state here and now that I am not trying to do these things; crazy indeed would I be to attempt them. I also know how difficult it can be to accept change, even when it is of the apparently mildest form. Consider, for example, the prospect of permanently changing from PG Tips to Tetley Tea (apologies for this analogy Tetley – in reality, I quite like your tea). So I am not saying it is a scientific fact that man can travel faster than light. Rather, I will just relate to you the situation, as I see it, surrounding this question of physics. It will then be up to you to make up your own mind. Now that I have issued my disclaimer, let’s ask: what is the maximum speed that man can travel at? This is another question that is easy to ask but may be very difficult to answer with certainty. We can be sure that it will become even more pressing in the future as we develop technologies that will drive us at increasing speeds through space. Naturally, mankind will wish to explore beyond the solar system – just as our ancient forebears wanted to know what lay beyond the hills or mountains on the horizon. Of course, if some of the potential threats discussed earlier become more acute, travel to other worlds may pass beyond a simple matter of curiosity towards a necessity for the survival of the species.

It should be emphasised early on in this discussion, that for over a century most physicists have believed that the ultimate speed that we could travel is just slightly less than the speed of light (c) - that’s to say around 180,000 miles a second. The reasons for this, which have to do with the theory that Einstein designated as ‘special relativity’, will be discussed in some detail below. If we are indeed limited to c, this would place some serious limitations on the practicality of deep space exploration and colonisation. Jim Kirk and company certainly would not have been able to zoom all around the Galaxy having adventures with alien species if the Enterprise could not have exceeded c. In fact, during his five-year mission, he would barely have had time to explore as far as the nearest star (after the Sun). Even more concerning would be the effect known as ‘relativistic time dilation’, which most physicists believe occurs when someone travels at speeds approaching that of light. The result of this would be that when Jim got back to the Earth after five years of travelling at high speeds, he would find everyone on Earth dramatically aged or perhaps even dead. But would this really occur and is it completely impossible to travel at speeds greater than that of light? I will endeavour to address these important questions below. Before doing so, I would like to mention that just because something is believed for 100 years, this does not guarantee it is correct. Before the publication of the special theory of relativity, scientists believed that space was absolute (rather than relative) and that in space light passed through a medium known as the aether (analogous to how sound travels through air). They thought this for many hundreds of years and there did appear to be quite a bit of evidence for it – but we now believe this to be wrong. It also does not matter if thousands, or even millions, of people believe a theory – it can still be wrong (remember Galileo). Finally, I feel we have to keep Clarke’s First Law in mind and those believing in the possibility of super-light speeds, could express this in the following way: When a distinguished but elderly scientist states that it is possible for man to travel faster than he has done in the past, he is almost certainly right. When he states that travelling faster than light is impossible, he is very probably wrong. Controversial I know, but there we are. In fact, having spent some years studying and thinking about this area of physics, I have noticed that many physicists appear to consider the idea of the impossibility of travelling faster than light to be almost an article of faith. To be honest, it seems like another case of the dogma of science – since faster than c travel has been considered to be impossible for the last 100+ years, they seem to wish it to remain so, and can get rather upset with anyone who suggests that it might just be possible that occasions could occur when c might be exceeded. Well, sorry guys, but if there is one thing I believe in more than anything else, it is the need for free thought and to keep an open mind. Yes indeed; in my own humble way I have been sitting in a corner with a towel around my head (figuratively speaking) racking my brains over this. And below I have sketched out my observations; sorry if they don’t fit in with commonly accepted wisdom. If, like Rupert Sheldrake, some will consider me a heretic … perhaps I should recant? But this wouldn’t achieve much since now I have written the ideas down. Once you have done this, particularly in the internet age, there is little you can do; now they are not just my ideas – they are everybody’s – to be considered and either accepted or rejected as you see fit.

Before we broach the tricky question of whether we can ever exceed c, let’s briefly review man’s quest for speed over the years. In the history of machines for transportation, there has often been an innovative development of the motive power needed, at the time concerned. An important example from the first half of the nineteenth century is that of the steam-powered locomotive. Many people believe that this was invented by Stephenson, but that honour has, in reality, to go to Richard Trevithick. This 6’2” Cornishman did not excel at school (one of his school masters described him as "a disobedient, slow, obstinate, spoiled boy, frequently absent and very inattentive") but he was good at arithmetic and had a talent for designing and building new types of steam engines.

Richard Trevithick, who invented the working steam locomotive, but who never got widespread recognition or financial reward for the invention . (Drawing by the author.)

Jumping forward, in the late nineteenth century, the advent of the motor car (a great invention if you ask me) led to the extended development of the internal combustion engine; while in the mid-twentieth century the invention of the centrifugal gas turbine for jet propulsion and its subsequent development as part of the WWII war effort, provided the power needed to accelerate jet aircraft up to the speed of sound and beyond. Then, in the second half of the twentieth century, the invention of manned rocket flight enabled a dramatic increase in travel speeds – of up to around 20,000 mph. (To be more precise, astronauts aboard NASA's Apollo 10 moon mission reached a top speed of 24,791 mph relative to Earth, as their rocket travelled back from the Moon on May 26, 1969.)

As we progress through the twenty-first century, humanity faces challenges on a greater scale than those previously experienced. Earlier sections of this book have considered future threats to mankind in some detail. As discussed, one of the most significant threats that has received world-wide attention is that of global warming. This certainly seems to present a potentially existential threat to humanity, with some scientists (such as Robert B. Laughlin, mentioned earlier) concluding that it constitutes such a threat that, no matter what measures were to be taken to address it, significantly influencing it would be beyond the capabilities of mankind. Such perceived risks have been motivating factors in the drive to develop new generations of spacecraft with the long-term aim of transporting humans to new worlds to assist in ensuring long-term survival of the human race. However, colonisation of alien worlds does itself pose a number of not insignificant challenges – most notably, the need to traverse the huge distances involved in reasonable time scales. The first stage on this journey was Neil Armstrong’s first step on the Moon in 1969; and the second is likely to comprise journeys to Mars, which are planned to occur within the next twenty years. By the way, last night I was out in the garden with my son – we were using the telescope I mentioned earlier to observe Mars. Apparently, the viewing was the best that will occur until 2033 and I can indeed confirm that the disk of the planet was nicely visible. We were contemplating the question of whether Mars will be the first planet beyond Earth to be colonised by humans and wondering when this might occur.

Given this situation, there are strong motivators for travelling beyond the solar system to discover if there are any habitable planets orbiting nearby stars in the Milky Way Galaxy. The problem here is that the distances involved, even to reach the nearest star systems, are so enormous that most people view the prospect as unrealistic or the subject of science fiction rather than potential science fact. The star nearest to the Earth (apart from the Sun) is currently Proxima Centauri, which is at a distance of 4.24 light years. To get an idea of the scale and distances involved, if the Sun were the size of a football and positioned in London, then Proxima Centauri would be the size of a tennis ball, but it would be located in New York! Despite this distance, the motivation for this exploration is, in fact, very strong – since astronomers have discovered a potentially habitable planet orbiting Proxima Centauri.

In order to enable travel across the immense distances between the stars, quite a large number of authors have written about ideas for high speed travel that employ methodologies that one might describe as fantastical. Some of these have included making use of various esoteric astronomical phenomena, including ‘wormholes’. The idea is that the latter can be created by connecting a black hole to a white hole (allegedly a region of space where nothing can enter). Apparently, when these two phenomena combine, they form a wormhole. Now, there is evidence that black holes exist in space, but that’s about all we can say here with any certainty. For example, if any unfortunate person tried to approach a black hole with a view to engineering the said wormhole, it is pretty certain they would be torn apart by an enormous gravitational field with their atoms then being unceremoniously dragged into the black hole at fantastic speeds. If it’s any consolation, it is likely that at this time their remains would emit a pretty flare of light and some X rays. Astronomers have actually observed X rays that they believe to originate from matter being sucked into black holes. Such X rays are believed by many to constitute evidence for the existence of black holes. Another little difficulty is that there is not a shred of experimental evidence for the existence of either white holes or wormholes.

Another potential method for initiating faster than light travel that is sometimes promulgated, is to employ the ‘warping’ of space. There is evidence that space is slightly distorted or warped by gravitational bodies – as predicted by general relativity – and measured by the apparent change in position of stars whose light has passed near the sun during total eclipses. This concept of distorting space led physicist Miguel Alcubierre to propose, in 1994, a method for changing the geometry of space by creating a wave that would cause space ahead of a spacecraft to contract and the space behind it to expand. The ship would then, apparently, ride this wave inside a region of flat space, known as a warp bubble, being carried along as the region itself moves due to the actions of the drive. There are though, a few practical problems associated with the proposed Alcubierre drive – the first of which being that it apparently necessitates the existence of ‘negative energy’ and therefore requires ‘exotic matter’ (it has this in common with wormholes, but last time I checked neither of these two items were available on Amazon). Another issue is that to function, it seems that such a drive would require rather a lot of energy. The theoretical physicist Lawrence M. Krauss has offered some rough estimates of the energy needed to create the incredibly high gravity fields that would be needed to warp space sufficiently to implement the proposed Alcubierre drive (as well as the concept discussed above, of enabling light to be bent to the extents required to implement a ‘cloaking device’ similar to the one invented in Star Trek by the Romulans). His suggestion is that to do this would require about as much energy as would be needed to produce a black hole the size of the Enterprise (he rightly points out that such a black hole would be able to bend any light beam that travelled near to it). It turns out though, that the mass of such a black hole would be around 1/10 of the mass of the Sun. Krauss observes that, expressed in energy units: “it would take more than the total energy produced by the Sun during its entire lifetime to generate such a black hole.” Jumping Jesus! So, you will excuse me if I find the likelihood of such drives being employed for high speed spacecraft travel to be a little unrealistic. I should just add that if you are wondering whether in Star Trek the use of the term Warp Drive to describe their method of faster-than-light travel came from the Alcubierre theory, in reality the opposite is true. Alcubierre stated in an email to William Shatner that the former’s theory was directly inspired by the term used in Star Trek ; and he also referred to the “Warp Drive of science fiction" in an article he wrote in 1994 about his theory. By the way, although Star Trek made the concept of Warp Drive famous, the term was actually first used by John W. Campbell in his 1931 science fiction novel, Islands of Space .

I mean he did so much – look at his general theory of relativity – not the sort of thing you would dream up over the pub and scribble onto a beer mat. It is, I fancy, rather more substantial than that and it’s been shown to be correct experimentally. His predictions for the bending of light near massive bodies (something that was touched on above) have actually been experimentally observed in the form of the apparent changes in the positions of stars whose light has passed near to the Sun during total solar eclipses. But, while not presuming to contradict the great scientist, is there any chance we could view all this speed limit business from a new angle (that sounds, I know, like a plan for a new road scheme). In short, can we beg to differ, not with Einstein, but with the conclusions that have been widely drawn in scientific literature as to the implications of SR for high-speed/interstellar travel?