How my granddaughter killed me

Malcolm Morgan takes a perilous journey thought time and finds that the future is all in the past.
My journey begins in 1915 when Albert Einstein published his theory of General Relativity. It started a new dawn of understanding of the universe, stemming from a new understanding of time. Before Einstein physicists had struggled with the concept of time, it obviously exists, but it cannot be seen, smelt, tasted, or touched, defining it seemed impossible. Most physicists believed time was just a universal clock ticking steadily forever keeping the universe in check. Einstein however, believed that space and time were intrinsically combined in a new concept he called Space-Time. We are all familiar with the three dimensions of space (height, width, and depth) but we also can also imagine time as a dimension, with the future in front of us and the past behind. We are all travelling along this dimension from the past to the future. Einstein showed that 3D Space and 1D Time could be combined as 4D Space-Time.
Einstein's first great breakthrough was to discover that Time was not absolute, but relative to the observer, this meant that one person could observe Time flowing at one speed and another person could experience Time flowing at another speed. Einstein was able to show that the faster you travel through Space the slower you travel through Time. If you are able to travel at the speed of light, Time will actually stop completely. Einstein's second breakthrough was to understand the link between Space-Time and gravity. Einstein imagined 4D Space-Time as a cosmic 2D sheet of rubber. Any object placed on the sheet would create a dent, the heavier the object the bigger the dent. The bending of Space-Time is what we know as gravity. Einstein was able to show that being close to a massive object was equivalent, relativistically to travelling very fast.
It is possible to test Einstein’s theories; if you climb to the top of the Warwick Arts Centre time for people on the ground would go 0.000000000000257% slower than it would for you, the longer you stayed on the roof the further into the future you would travel. Sergei Krikalev holds the current record the having travelled the furthest through time. He is the Russian Cosmonaut who has spent the longest period in space (748 days) during those flights he has travelled 1/50 of a second into the future.
This is not a very effective way to time travel, so physicists started to look for other ways. Unfortunately, they always came across the same problem; they could only slow time down. It is possible to travel forward in time but not back. The only way to travel backwards in time would be to go faster than light, which is currently thought to be impossible. Even if you did travel faster than light, it would impossible to travel back before the creation of the time machine.
 

Figure 2: A diagram showing how Wormholes can allow short cut from one place in Space-Time to another.
 In 1939, physicists had the idea of taking a short cut across Space-Time. Physicists call these short cuts, Wormholes. Imagine if the Space-Time sheet of rubber was not flat but folded as shown in the picture [ABOVE BELOW ETC]. If a beam of light and a spaceship started from the same point in Space -Time (A) the light must travel along the surface of the sheet (the red path). However if the space ship was able to travel through a Wormhole (the yellow path) it could arrive at its destination (B) before the light ray, while still going slower than the speed of light. To an external observer, who did not know the space ship had a Wormhole; it would appear that the ship could travel faster than light.
In 1963, Roy Kerr predicted that a spinning black hole would have some unique properties. Black holes are stars, which have collapsed until they are smaller than an atom; their gravity is so strong that not even light can escape. At the centre of the black hole is a Singularity, an object with huge mass but no volume, thus an infinite density. In a Singularity, all the laws of physics break down. The Singularity inside a spinning black hole is shaped like a doughnut; the hole in the centre of the Singularity would behave like a Wormhole. Wormholes have two major problems; firstly, the immense gravity around it would cause Spaghettification, the technical term for being stretched until you are hundreds of meters long and thick as a hair, this is probably fatal. Secondly, to create a Wormhole you would first have to make a hole in Space-Time; this would cause the Wormhole to collapse instantly. The only way for a Wormhole to stay open is if negative energy inside the wormhole holds it open. To understand negative energy we must go back to 1905 when Einstein was able to show that Mass and Energy are equivalent with his famous equation E=mc2. Even empty space has small amounts of “Vacuum Energy” caused by the interaction of the Fundamental Forces. If the Vacuum energy could be lowered until it had a value less than zero, a particle with a negative mass would be created. This would have negative gravity, repelling mass rather than attracting it. This particle could hold open a wormhole. Physicists have not yet been able to create such particles but they have been able to lower the vacuum energy to near zero values.
Wormholes could provide a viable way to travel in time but they are too far away for everyday use. Fortunately, two Russian physicists have the solution. Irinan Aref’eva and Igor Volovich, have shown that the Large Hadron Collider (LHC) due to be completed this year could potentially make mini-Black Holes and Wormholes. If this where to happen then 2008 would become year zero for time travellers, the first year which people from the future can visit. The LHC will be the world’s largest particle accelerator. It is housed in a 27km long circular tunnel, the accelerator itself contains 1600 magnets cooled to -273oC with liquid helium.

Suppose that I visited the LHC and took a trip to 2053, I could not only meet up with my future self but also my yet unborn children and grandchildren. Suppose I was travelling with my granddaughter in her car, she crashed, and I was killed. What would happen? If I died in 2053, I could not have children, so my granddaughter could not have been born, so she could have not driven the car, which caused my death in the first place. Physicists call these problems Time Paradoxes. Not all time travel results in paradoxes, suppose that a man travels back in time to discover the cause of a famous fire. While in the building where the fire started, he accidentally knocks over a kerosene lantern and causes a fire, the same fire that would inspire him, years later, to travel back in time. Although confusing this is not impossible, it results in a “chicken and egg” situation where cause and effect are inseparable. Genuine paradoxes cause a real problem for theoretical physicists, none of the laws of physics prevents them from happening but they break causality. One of the most fundamental beliefs of all scientists is that every event has a cause and the cause always precedes the effect.  For example, the table fell over because the wind blew it, not the table fell over causing the wind to blow. Due to these paradoxes, Stephen Hawking suggested his Chronology Protection Conjecture, that when you attempt to cause a paradox, nature would conspire to prevent it. Other scientists have postulated that our free will is chronologically handicapped preventing us from making choices that would have an adverse affect on the timeline. None of this is know for sure but we can expect some of the answers in the next few years as physicists push causality to its limits. Chronology Protection Conjecture or not, I think I will be having some serious discussions about driving with my granddaughter, or as my 2053 self would say, I had.

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