The Time Traveller (for so it will be convenient to speak of him) was expounding a recondite matter to us. His grey eyes shone and twinkled, and his usually pale face was flushed and animated. The fire burned brightly, and the soft radiance of the incandescent lights in the lilies of silver caught the bubbles that flashed and passed in our glasses. Our chairs, being his patents, embraced and caressed us rather than submitted to be sat upon, and there was that luxurious after-dinner atmosphere when thought roams gracefully free of the trammels of precision. And he put it to us in this way--marking the points with a lean forefinger--as we sat and lazily admired his earnestness over this new paradox (as we thought it) and his fecundity.H.G. Wells, The Time Machine
'You must follow me carefully. I shall have to controvert one or two ideas that are almost universally accepted. The geometry, for instance, they taught you at school is founded on a misconception.'
'Is not that rather a large thing to expect us to begin upon?' said Filby, an argumentative person with red hair.
'I do not mean to ask you to accept anything without reasonable ground for it. You will soon admit as much as I need from you. You know of course that a mathematical line, a line of thickness nil, has no real existence. They taught you that? Neither has a mathematical plane. These things are mere abstractions.'
'That is all right,' said the Psychologist.
That is how H.G. Wells' starts his story about time travelers. As it happens, certain Physicists today have controverted not one or two but dozens of ideas that are almost universally accepted, the result being that a layman is left with no clues at all about what is serious and what is just another weird and sensational speculation. I would like to bring some rationality to this exciting topic.
Last Friday, sensational news circulated in the media. "The Independent" published an article The Big Question: Is time travel possible, and is there any chance that it will ever take place?
An inspiring picture accompanied the text:
The media excitement is all due to a paper published by a pair of Russian physicists (I have had the pleasure to meet both of them) from Steklov Mathematical Institute in Moscow, I. Ya. Aref'eva and I.V. Volovich. Actually, the paper has been circulating in the scientific community since October of last year and has the title "Time Machine at LHC". If someone is really interested, the paper is available from the preprint repository at Cornell.
What is this paper really about? Is it really about "Time Travel"?
There are certainly some speculations concerning the possibility of creating little time machines during the high-energy collisions of protons in the Large Hadron Collider (LHC) at CERN, Geneva.
If, long ago, we were imagining that the time machine will look like this:
|Another version of the Time Machine
...today our imagination about a mini-time-machine is somewhat different:
|Large Hadron Collider = Time Machine?
The paper talks about an experiment in the Large Hadron Collider where protons will be accelerated and run around in two opposite directions in a circular tunnel of 27 km length. When the speed is "right", the two beams will be made to hit each other. Kaboom! We have fireworks. Our pair of Russian physicists speculate that, as the result of these high-energetic collisions the local (as in teeny-tiny) geometry of space-time may change, and there can be a local (again, teeny-tiny) reversal of causality. In other words: time travel. But on a very, very tiny scale; so tiny, no one will be able to see it!
So, what's the deal really considering the sensational speculation in the media?
Everything that follows is my personal opinion. I do not expect the reader to take it as the bottom line, the "truth," but I do want the reader to understand that I am an expert in these topics so it can be considered a very "educated" opinion. At the same time, I am trying to be open-minded, yet constructively critical. I am open to all ideas - as long as they do not contradict the totality of data and knowledge that we have, while at the same time being critical concerning the conclusions that are being made. I am also sensitive to the "small print" that we find in scientific papers. The journalist often misses the important keywords that scientists add here in there to signal the facts to other scientists and keep them out of hot water with their colleagues.
So, let us take an analytical look at certain aspects of the paper by Aref'eva-Volovich, paying special attention to the keywords. In the Abstract of the paper we immediately find:
"if ... quantum gravity ... proton-proton collisions could lead to the formation of time machines..."Pay attention to these words: "if ... quantum gravity".
First of all we (scientists) have no idea if quantum gravity makes any sense whatsoever. There is considerable dispute as to whether or not gravity should even be quantized. So, using "quantum gravity" right from the start is a highly questionable premise. Secondly, if quantum gravity is assumed in this case to be sensible, its use here should have the sense required by the premise. Third, even if quantum gravity is ever theoretically constructed and if it has the required properties, then still we are not sure, since we read in the above sentence that it "could lead to time machines" rather than it "would lead to time machines".
After reading such an abstract we might be inclined to completely discard the paper as nonsense, but the fact is, there are some little pearls in there that I would like to highlight for the reader.
On the second page we read that in Einstein's general relativity we have the so called "Thorn's hoop conjecture" - a conjecture concerning the formation of black holes. The layman may be somewhat surprised here because physics is usually represented as an exact science and here is the term "conjecture." In an exact science, why do we need conjectures? We have the theory, we have equations, all well established, so why do we need conjectures? All you need to do is just sit down and calculate and forget about making conjectures, right?
Not exactly. This is a mistaken view of non-physicists. Physics is full of conjectures because of the lack of definitive progress over the past hundred years of research. Physics has, in fact, become the "science of conjectures," and this is a very bad situation because we really need to understand our reality. Why is it full of conjectures?
Because it is stuck. Gravity and Quantum Theory do not like each other and no one has been able to break this staring match for a hundred years.
Why? Because politics and money took over physics; truth doesn't count anymore. What counts is using physics for armaments and everyone else just follows the easy way: physics as a career, publish or perish, doesn't matter if it leads to the truth or not, what matters is that it makes a living.
Getting back to the article: a few lines after we meet another conjecture, this time coming from "string theory" - one of the popular, well-funded lines of research that has led nowhere. Next page we have several "scenarios" being discussed. The question naturally arises: are we doing physics or making a movie? If it is a movie, it is a sci-fi movie, because the main roles are being played by "plane gravitational waves". The act is, despite the spending of millions of dollars with many physicists making a good living, gravitational waves have not yet been seen; no plane ones or round ones with eyes and ears. But here, in this paper, we see that such exotic actors have already been hired as the main characters in the "scenarios".
Just a few lines further in the article, we read that even if the actors are alleged to be available for the making of the movie, even then "one can argue that ... ." One can "can argue that" what? That "there is an exciting possibility of production of black holes, branes and Kaluza-Klein modes from the extra dimensions..." And all that will "suggest the possibility of time travel with its well known paradoxes."
What a leap!
We also learn from the article that there will be those who will argue against these exciting possibilities. The opponents will base their arguments on another famous conjecture, the conjecture of the great Stephen Hawking himself! To make it look more serious, not just another conjecture, it has the name: "Hawking's chronology protection postulate". Stephen Hawking will protect us from messing up chronology! Right. Now we have Superman in the movie!
In the next paragraph we finally see that there is no difference between science and religion. The authors write: "Moreover, if one believes that there exists a full theory of quantum gravity, then ...". The reader may want to read three times this "if one believes". This is not physics, this is a fairy tale. Personally, I don't want to believe. I want to know.
I have nothing against bold hypotheses, but it is necessary to learn how to read the papers written by physicists and to be immune to sensational articles such as in The New Scientist, the journal that has made our couple of Russians famous: "2008: Does time travel start here?"
Years ago H. G. Wells did a better job than this, since his hero scientist was announcing: "I do not mean to ask you to accept anything without reasonable grounds for it." Aref'eva and Volovich are asking us to "believe".
Finally, do I think that time travel is possible?
Of course I do.
Do I think that we can learn anything about time travel from these experiments in LHC?
Of course, not.
Simply because the speculations of many, if not most, physicists are based on theories built on quick-sand, and the interpretation of the results of the experiments depends on the assumed theory - assumptions in front and after, and be damned to any data that does not fulfill the expectations and beliefs.
Do I think that the experiments with LHC can bring us something new and interesting? I think there is such a possibility, especially if they will bring new data that cannot be explained by any of the existing candidates for theories. But then that data must be analyzed fully, objectively and without pre-formed assumptions or beliefs.
It strikes me that the only Time Machine in operation here is in the minds of those who wish to transport all of us back to the Dark Ages.
Arkadiusz Jadczyk is a Mathematical Physicist, an expert in Kaluza-Klein theories, hyperdimensional physics and Clifford Algebras. Visit his website.