Time Travel… Possible or Not??
Time travel — moving between different points in time — has been a popular topic for science fiction for decades. But is time travelling possible? Can human jump back to the past to change his/her present or future. Or can they go to the future for an exciting trip? Well, that is a tough question to answer because many of the scientist believe time travelling is not possible at all. Some even say that an attempt would be fatal to any human who chooses to undertake it. Yet, many of them do believe that time travelling is possible.
Understanding what is time?
What is time? While most people think of time as a constant, physicist Albert Einstein showed that time is an illusion. It is relative, it can vary for different observers depending on your speed through space. To Einstein, time is the “fourth dimension.” Space is described as a three-dimensional arena, which provides a traveler with coordinates, such as length, width and height showing location. Time provides another coordinate direction although conventionally, it only moves forward.
Einstein’s Theory of Special Relativity which is published in 1905 says that — Time slows down or speeds up depending on how fast you are moving relative to something else. Which means time is not fixed everywhere rather it is relative to other variables depending on the speed of the observer against another relative object. For an example, Approaching in speed of light in a spaceship, a person ages much slower then he would age in the earth.
Another example is, Say you were 15 years old when you left Earth in a spacecraft traveling at about 99.5% of the speed of light (which is much faster than we can achieve now), and celebrated only five birthdays during your space voyage. When you get home at the age of 20, you would find that all your classmates were 25 years old! Because time passed more slowly for you, you will have experienced only five years of life, while your classmates will have experienced a full 10 years.
Also according to the Einstein’s Theory of General Relativity — Gravity can bend time itself.
How gravity can bend time? This can be explained by a simple explanation. Lets assume a fabric which represents as space-time. When anything that has mass sits on that piece of fabric, it causes a dimple which represents bending of space-time. The bending of space-time causes objects to move on a curved path and that curvature of space is what we know as Gravity.
Both the General and Special relativity theories have been proven with GPS satellite technology that has very accurate timepieces on board. The effects of gravity, as well as the satellites increased speed above the Earth relative to observers on the ground, make the unadjusted clocks gain 38 microseconds a day.
In a sense, this effect, called time dilation, means astronauts are time travelers, as they return to Earth very, very slightly younger than their identical twins that would remain on the planet. So in a sense Human can jump to the Future if he/she can achieve Speed of light in a spaceship and travel out side space for a period of time i.e 5–10 years and come back to the earth and he/she will see 10–20 years have been already passed in the planet Earth.
Theoretically time travel can be done in many ways i.e. Through the wormhole, Black holes, Cosmic strings and many other theories. Lets talk about these few described above.
Through the Wormhole
Einstein’s General relativity also provides scenarios that could allow travelers to go back in time, according to NASA. The equations, however, might be difficult to physically achieve.
One possibility could be to go faster than light, which travels at 186,282 miles per second (299,792 kilometers per second) in a vacuum. Einstein’s equations, though, show that an object at the speed of light would have both infinite mass and a length of 0. This appears to be physically impossible, although some scientists have extended his equations and said it might be done.
A linked possibility, NASA stated, would be to create “wormholes” between points in space-time. While Einstein’s equations provide for them, they would collapse very quickly and would only be suitable for very small particles. Also, scientists haven’t actually observed these wormholes yet. Also, the technology needed to create a wormhole is far beyond anything we have today.
Black Holes
Another possibility for time travel would be to move a ship rapidly around a black hole, or to artificially create that condition with a huge, rotating structure.
“Around and around they’d go, experiencing just half the time of everyone far away from the black hole. The ship and its crew would be traveling through time,” physicist Stephen Hawking wrote in the Daily Mail in 2010.
“Imagine they circled the black hole for five of their years. Ten years would pass elsewhere. When they got home, everyone on Earth would have aged five years more than they had.”
However, he added, the crew would need to travel around the speed of light for this to work. Physicist Amos Iron at the Technion-Israel Institute of Technology in Haifa, Israel pointed out another limitation if one used a machine: it might fall apart before being able to rotate that quickly.
Cosmic Strings
Another theory for potential time travelers involves something called Cosmic Strings — narrow tubes of energy stretched across the entire length of the ever-expanding universe. These thin regions, left over from the early cosmos, are predicted to contain huge amounts of mass and therefore could warp the space-time around them.
Cosmic strings are either infinite or they’re in loops, with no ends, scientists say. The approach of two such strings parallel to each other would bend space-time so vigorously and in such a particular configuration that might make time travel possible, in theory.
Time Machines
It is generally understood that traveling forward or back in time would require a device — a time machine to take you there. Time machine research often involves bending space-time so far that time lines turn back on themselves to form a loop, technically known as a “closed time-like curve.”
To accomplish this, time machines often are thought to need an exotic form of matter with so-called “negative energy density.” Such exotic matter has bizarre properties, including moving in the opposite direction of normal matter when pushed. Such matter could theoretically exist, but if it did, it might be present only in quantities too small for the construction of a time machine.
However, time-travel research suggests time machines are possible without exotic matter. The work begins with a doughnut-shaped hole enveloped within a sphere of normal matter. Inside this doughnut-shaped vacuum, space-time could get bent upon itself using focused gravitational fields to form a closed time-like curve. To go back in time, a traveler would race around inside the doughnut, going further back into the past with each lap. This theory has a number of obstacles, however. The gravitational fields required to make such a closed time-like curve would have to be very strong, and manipulating them would have to be very precise.
Grandfather Paradox
Besides the physics problems, time travel may also come with some unique situations. A classic example is the grandfather paradox, in which a time traveler goes back and kills his parents or his grandfather.
If that were to happen, some physicists say, you would be not be born in one parallel universe but still born in another. Others say that the photons that make up light prefer self-consistency in timelines, which would interfere with your evil, suicidal plan. Some scientists disagree with the options mentioned above and say time travel is impossible no matter what your method
So is time travel possible?
According to all the possible theories presented in this article there might be a slight possibility for time travel but it would be very difficult. With the physics that we use today, it is quiet impossible for now but the field of physics is constantly changing. Advances in quantum theories could perhaps provide some understanding of how to overcome time travel paradoxes. If the physics is well developed enough in the future, who knows Time Travel might be even possible with these theories or even better theories might come up by Scientists in Future.
