Hey there readers! I am so excited to tell you about the latest thing I fished out from Google–
“THE CHRONOLOGY PROTECTION CONJECTURE”!
Sounds geekish doesn’t it? Its quiet simple to understand at the same time.
Divided on Time-Travel
Apparently the Physics community is divided on the possibility of time travel. Majority of the community believes that time travel ‘could be’ made possible in the ‘near future’ (with researchers working on things like closed time-like curves caused due to quantum gravitational effects and general relativity). Quiet ambiguous a note reverberates in their voices. Research on the same is yet in its pre-natal state. Theoretical explanations are controversial and are being debated and developed by the community. Scientists are expecting breakthroughs in the science and philosophy of time only after a stable theory of Quantum-Gravity is completely developed and established.
Yet there are a few physicists who sit at the other end of this shaky-little boat of time travel science. They are individuals who believe that time travel is impossible, but only at the ‘macroscopic’ level. Marks the before-said words very carefully. Stephen Hawking, the famous Emeritus Lucasian Professor of Mathematics of the Cambridge University, known the world over for his science television shows, his books including the very famous ‘A Brief History of Time’ and his and fellow scientist Roger Penrose’s theoretical discovery of the Big-Bang singularity; came up with this idea and called it the Chronology Protection Conjecture.
The Chronology Protection Conjecture
To quote him:-
It seems that there is a Chronology Protection Agency which prevents the appearance of closed timelike curves and so makes the universe safe for historians.
In normal English, what he is trying to say is that time travel in any direction is not possible at the macroscopic level (level of cellular and human existence) but it is possible and continually takes place at the microscopic or the quantum level (that is at the level of the electrons).
Technical Explanation (for the geeks)
The technical part of the conjecture, if you can bear and understand it, is that any time machine which exists at the macroscopic scale will destroy itself or that a person outside the machine would not be able to enter it. The reason being that due to vacuum fluctuations, the energy density at the boundary of the time machine (the Cauchy Horizon) will increase to infinity hence destroying the machine itself. In short, closed time-like curves at the macroscopic level are very unstable and can be deemed to be non-existent. This conjecture is completely based on the General Theory of Relativity and the Semiclassical theory of Gravity. To understand this in depth, links given at the end of the article will be useful.
Comparison with NOTSOSCIENTIFIC’s deductions
If you have read the earlier articles published at NOTSOSCIENTIFIC (namely Never Back in Time and Future Tense), I believe you have noticed by now that our deductions through basic scientific methods (collectively called as the Layman’s common sense) also pointed at the same end as do the conjectures of scientific biggies like Stephen Hawking. Those articles showed through basic common-sensical methods that time travel to the past or the future is impossible, atleast according to the Layman’s current knowledge of Science. Ofcourse these deductions of ours were also only applicable at the macroscopic scale because that is what we considered our case to be, besides physics changes grossly at the microscopic scale. This conjecture is a big supporting pillar for our common-sensical methods. Do remember though that this does not deem the Layman’s approach as scientifically correct. Yet it shows that the scientist and the Layman may reach at the same conclusion through their own methods in their own sweet time (the Layman’s time being maybe a day or two compared to the years of research spent by a scientist, yipee! But the scientist’s methods are bound to be better and scientifically well established when compared with ours).
So when do I get to Time-Travel?
Currently ‘time’ stands as a topic of deep study and research in physics and philosophy. The field remains unexplored largely due to the basicity of understanding and vastness of imagination it demands which only a few posses; and the need for new mathematical methods.
All I can give you for now to suffice your excitement about the probability of time-travel is this:
Imagine why Newton sat alone in the Garden when the holy apple fell? Why were not physicists from the future, who had built time machines, present there to witness this great event? Why did not Edison mention in his accounts that his lab used to be filled with scores of mysterious and curious kids (looking like more evolved humans) who used to pop out from thin air and vanish back again after having a look at the light bulb?
Maybe time-travel will be banned in the future once it is made possible so as to ‘make the universe safe for historians’ as Hawking puts it. Or maybe only time-travel to the future will be allowed. The gravest possibility could be that time-travel would never be made possible! Quite creepy possibilities these are. Yet one can only hope and work at it. With physics today using a many-worlds interpretation of quantum-mechanics, anything and everything can be possible in the future.
If we do discover a complete theory, it should be in time understandable in broad principle by everyone. Then we shall all, philosophers, scientists, and just ordinary people be able to take part in the discussion of why we and the universe exist.
– Stephen Hawking