The Physics of Time
Sir Isaac Newton was for all intents and
purposes the inventor of modern physically theory. His ideas
about motion and force for the most part still have great value
today. There have only been corrections to his theory since its
inception but nothing has every replaced it.
In his theory time was always the same for any observer in any reference frame. For several hundred years, from 1687 to 1905, this is the belief that was held as true by people all around the world. However, in the end of the nineteenth century a change was developing in the way that time was viewed in physics.
The development of the equations of electromagnetic by James Maxwell led others to investigate their consequences. Among those investigators was none other than Albert Einstein.
Just as man was harnessing the power of flight, Albert Einstein, then a young patent clerk, introduced his special theory of relativity and then later his general theory of relativity. His theories suggested the most strange and wonderful things, that time was not a constant, that it was changeable. His theories suggested that objects that we accelerated to higher speeds would shrink and grow heavier; also that time would past slower for these fast-moving objects than for those objects that were left behind.
The impact of his theory is shown in a story called the twin paradox. The twin paradox describes how an astronaut that travels to a distant star and returns to earth will be younger than the twin brother she left behind. Today we know this is not science fiction. It is today’s science fact.
Later, Einstein suggested that the acceleration we feel as we move to higher speeds is equivalent and really cannot be distinguished from the accelerations we feel due to gravity. Imagine being in a closed box, like an elevator, with no windows or knowledge of what is outside and around us.
Can we really tell whether the acceleration we feel as the elevator moves up is from the force of an elevator, or the thrust of a rocket, or from the force of gravity? So now it is suggested that not only high speed but also heavy gravity can dilate time.
Einstein’s views were not immediately accepted. In fact, it would take years before his theories were understood and embraced by the scientists of the world. But we will see later how his theories were proven and then how they transformed our view of science and the world forever.
However, in the early nineteen hundreds this was the world of science fiction not science fact. But science fiction did have an influence on the development of the science fact of time travel. Science fiction has always been the springboard of science. The power of imagination is often lighting the path to real science and science fiction’s influence in leading the way to understanding the nature and science of time and time travel is no exception. As is often said, “To do one must first imagine.”
In 1905 Einstein introduced his special theory of relativity. It suggested that very fast speed can dilate time. What this would mean, if true, is that time in not unchangeable and that time travel to the future would be possible. But Einstein’s views and theories were not accepted or taken very seriously by many people at this time.
Then in 1916 Einstein introduced his general theory of relativity. This suggested that heavy gravity could curve or bend spacetime and that it could also dilate time. Again his theory was not accepted. However, there was one interesting point about Einstein’s general relativity that caught the attention of scientists around the world.
For hundreds of years the Newtonian model of the universe served scientists well. They were even successfully used to predict the orbits and locations of planets in the heavens. But there was known to be a flaw in Newton’s model. It seemed they could predict the locations and orbits of all the planets, except Mercury, the planet closest to the sun.
Is it possible that the gravity of our massive sun was distorting space and time around this planet? In fact it was and Einstein’s theory of general relativity explained it almost perfectly. General relativity explains the Mercury orbit, however, Einstein’s theories of relativity were still not accepted.
Most scientists thought that this was just a mathematical trick or coincidence. They didn’t believe that space and time could possibly be curved. But to a few, Einstein’s theories became more than just a curiosity and to prove it all they needed to do was to demonstrate that a massive body with very heavy gravity could curve space and time.
Well, not the easiest problem to solve in the early nineteen hundreds. That was until a suggestion was made that could prove once and for all whether Einstein’s theories were true or false.
The idea was to look at the light of a distant star that was passing near the edge of the sun and then compare its measure location here to its measured location when the sun is not between it and the earth.
A perfect idea. If the gravity of the sun could truly bend space around it then the measured locations would be different. The only problem, to do this, we would have to be able to look up at the sun and see starlight in the middle of the day. Not an easy task considering how bright the sun is and that we can’t see starlight in the daylight, except during a total solar eclipse.
An incredible excitement grew and expeditions from all around the world were sent out to view the eclipses of 1919 and 1921. As results came in from around the world it was clear, Einstein’s theories were correct. In fact, his predictions were so accurate that all the doubt around his theories fell and Einstein’s theories were finally accepted and the world opens its eyes to a new reality and new science.
Time is no longer a constant. Newton’s universe crumbles and the race to explore the new nature of time and space begins and is followed by a flurry of events and advancements.
In 1937 Kurt Gödel proposes that the universe is a time machine. In his model of the universe it was theoretically possible in these worlds to travel through time. In 1949 Kurt Gödel again proposes that pathways through time are possible using something called closed timelike curves, an idea that shows how heavy gravity can curve space and time in a way that might allow time to actually loop back on itself into the past.
His work was the first to suggest that reverse time travel could be possible without violating the laws of mathematics and physics.
General relativity predicts that if a massive star experiences a total gravitational collapse that a singularity in space and time would be formed. This object could have a gravitational field so large that even light could not escape it.
Appropriately in 1967 the great American physicist John Wheeler introduced the term “black hole” to describe this spectacular singularity in space and time, a term that is well known today. It is speculated that the singularity at the center of a black hole might be a place perhaps where time itself ceases to exist.
Later in 1974 Frank Tipler shocked the scientific community when he published a paper that appeared to be plans for building a time machine. Using a massive rotating cylinder in space Tipler showed how not only forward but reverse time travel were both possible without violating the laws of mathematics and physics.
By flying through a carefully plotted spiral course around the cylinder a traveler could find himself moving both forward and backwards into time. This rotating cylinder model continues to be one of the best examples that shows how time travel is clearly possible.
In 1986 David Lewis Anderson introduced of what is called today “Time-warped Field Theory.” Time-warped field theory is an approach that allows the creation of a field within which time rates can be adjusted without requiring the massive amounts of energy that was previously thought to be needed. Within the boundaries of a time-warp field it is possible to actually accelerate or decelerate, to certain degree, the rate at which time passes relative to the rate of time outside of the field.
Another scientist today making many contributions to spacetime study is Kip Thorne. Kip Thorne has suggested many methods of using wormholes for time travel. In one example, using a rotating black hole, he showed that it might mathematically possess in its interior hyperspace tunnels to other spaces either in our universe or perhaps to other universes.
A wormhole in effect could connect two places separated by a very large distance to each other through a distance that was very small inside of the wormhole. Thorne’s approach would require an advanced technology that could master and use the energy within the black hole to make the trip. But in a different way Thorne shows here once again that even though time travel may be very, very difficult it is not impossible. As his work continues Dr. Thorne has even suggested using exotic matter to capture and control wormholes that might occur naturally at the quantum level in what is called the quantum foam.
The advances following the acceptance of Einstein’s theory of relativity have been many and since the 1920’s his theories continue to be proven over and over again in many different ways.
The most important realization out of all of this is that forward and backward time travel does not violate the laws of math and physics. And as we know, when mankind knows something is possible we usually find a way to make it happen.
One of the most interesting moments in the recent history of spacetime development was that of Stephen Hawking when he published his famous Chronology Protection Conjecture. In this work he denies the possibility of time travel because we have not been invaded by hordes of tourists from the future. Using this almost as experimental evidence he really stopped and made the scientific community pause and think deeper about the possibilities of time travel.
So if time travel will be possible where are all the time travelers from the future? From here many theories were raised. Perhaps we’ve not seem them because when a time traveler comes back in time a parallel universe is born where he exists but we don’t. Or perhaps, time travelers cannot go back any earlier than when the first time machine is built.
Or perhaps, many people might say there is evidence that we have seen time travelers from the future. Millions of people from around the world, people including doctors, scientists, presidents and kings and many others have claimed to have sightings or encounters with unidentified flying objects and aliens.
Is it possible that these sighting are time travelers from our own distant future?
In 1991 Richard Gott suggested another way to create pathways backwards in time. His idea was based on a theoretical object called a cosmic string that might be left over from the creation of the universe. If two cosmic strings were to pass close to each other, or one was to pass near a black hole, a pattern of closed time-like curves could be created. By flying a carefully calculated course around the string it would be possible to emerge anywhere, anytime.
The concept and basis for “many worlds” theory in science was pioneered by Hugh Everett III. The many worlds theory states that if a time traveler returns to the past and makes a change then reality will split into two timelines, one where the change never happened but also an alternate timeline where the change did happen. Perhaps in every second our reality continues to split into an unlimited number of parallel timelines. It’s a fascinating concept and one that still attracts serious researchers today.
Later, in another move that shocks the scientific community, Stephen Hawking announces that he believes that time travel is now possible and like many scientists he even encourages more funding and research to advance our understanding of the physics of time.
When we speak about time and time travel we must also speak of the fascinating new theories of hyperspace and also superstring theory. One of the world’s leading scientists in this area is Michio Kaku. At the end of Dr. Kaku’s quest for the theory of everything we may find answers that will unlock the deepest secrets of creation and answer some of the most intriguing questions of all time such as what happened before the big bang, whether the past can be altered, and if gateways to other universes really exist. His work and vision is truly remarkable and is leading the way in helping us all to understand the true meanings of space and time.
The quest for the technology permitting time control is now underway. Private and government investment in this area of research is on the rise all around the world and is and fueling a race leading to discoveries that will change our world and our very sense of reality in ways difficult to even begin to comprehend.