Quest to a Perpetual Hourglass

Secret to the universe’s greatest mystery

It is the most common noun in the English language and used in a range of proverbs. It flies when we have fun and along with the tide it waits for no one. You try to race against it and often wish you had more of it. Time is one of our universe’s greatest mysteries and physicists spend their lives trying to understand even a fraction of it.

Wouldn’t it be cool to go into the future, have a peek into your successes and failures, come back and fix it all? In theory, it is surprisingly simple; all you must do is travel at the speed of light. So, why hasn’t anyone taken a trip through time? Actually, everyone has. You, your neighbour, your local newsagent, astronauts and Usain Bolt. The only difference is how far ahead in time. This is all because of time dilation, the difference in elapsed time. Elapsed time simply means the amount of time that passes from the start to the end of an event. For example, if you had two identical clocks, one stationary and another one moving close to the speed of light, the moving clock seems like it is measuring a shorter time or moving more slowly relative to the stationary clock. This applies to other bodies as well. Humans have an internal clock and the faster they move, the slower their internal clock runs, allowing them to travel forwards in time.

For instance, if you race against Usain Bolt in a 100m race, he will reach the finish line a couple of seconds before you do, well, assuming you are really fast! This means he has reached the future quicker than you have as he has travelled a fraction of the speed of light faster than you. The closer you go to the speed of light, the more apparent are the effects of time dilation. Astronauts aboard the ISS, which travels at 0.000002% the speed of light, experience time dilation on a measurable scale. Astronauts coming back from a 6-month mission are actually 0.007 seconds ahead of us. As the average human reflex speed is 0.21 seconds, this doesn’t make a massive difference. However, some cosmonauts like Oleg Kononenko, a Russian astronaut who has spent a whopping 1111 days in space might be a couple of seconds, ahead in time.

If you (a person who hasn’t experienced time dilation on a measurable scale) and Kononenko were standing next to each other at a shooting range, Kononenko would see each shooter hit their target 2-3 seconds before you do. Depending on the distance between the shooter and the target, he may see the target being hit before the shooter has pulled the trigger!

If a person is able to travel a couple of seconds into the future, then how hard could a couple of years be? Unfortunately, Einstein has made that quite difficult due to his special theory of relativity which states that the speed of light in a vacuum is the same for all observers. This is also where his very famous equation E = mc²  comes from. This can be rearranged to say

m/s. Therefore, for a small mass, you will need infinitely more energy than is describable to travel at the speed of light. For many humans as well as their spacecrafts, the amount of energy required may be greater than the amount we have in this universe itself!

Travelling at the speed of light is ruled out but what if I told you that there was another way to travel into the future. A way which allows our feet to be younger than our head. As your feet are deeper in the Earth’s gravitational field then your head, it reaches the future first. Similarly, if you spend an average lifespan of 72 years living in La Rinconda, the highest permanent human settlement, situated in the Andes at an elevation of 5,000 meters, then you would be 0.0025 seconds further ahead in time than someone who had been living their whole life at sea level. The person living at sea level is deeper in Earth’s gravitational field and therefore less time passes for them.

Everything has a gravitational field strength, however, the heavier the body the stronger its gravitational field strength (g). As the earth’s gravitational attraction is not strong enough to experience time dilation on a measurable scale, one must turn to the heavier celestial bodies. Luckily, there are some bodies that are a trillion times heavier than the Earth. We call these black holes. They are dense and heavy with a gravitational strength so strong that not even light can escape once it has crossed the event horizon, a point of no return.

A black hole’s gravitational attraction is so strong that if you sit just 10km away from the black hole’s event horizon for 7 years then 7,000 years would pass on Earth. This seems like a possible solution for travelling into the future but there is a catch, like with most laws of physics. Our nearest black hole is Gaia BH1 which lies in the direction of the constellation Ophiuchus. To get near the black hole’s event horizon and back to Earth, one must travel for 3,000 years and that too at the speed of light. As the average lifespan of humans is currently 72 years that is not possible.

So, if you’re hoping to pick up next week’s test paper or perform the latest trends with aliens from outer space, I’m afraid you have to wait, but it might be for the best. The future is unpredictable, and we do not know whether humans would even be alive in 1,000 years, therefore it is best to stick to dreaming about meeting moon colonies or watching the latest sci-fi movies.