Although humans cannot time travel inside a time machine, we now know that clocks on aeroplanes and satellites run at a different speed than those on Earth.
We are all moving through time at this moment. For example, we spend a year between birthdays. And we’re all moving at roughly the same speed: 1 second per second.
NASA‘s space telescopes give us a way to see the time. Telescopes help us see distant stars and galaxies. Light from distant galaxies takes a long time to reach us. So, when we look at the sky through a telescope, we see what those stars and galaxies looked like long ago.
However, when we think of the topic “time travel”, we usually think of travelling faster than 1 second per second. You have seen such time travel events countless times in movies or science fiction books & tv series. But is it really possible? According to science, yes it can!
How do we know that we can time travel?
The most powerful idea about how time works were made more than 100 years ago by Albert Einstein. He called it ‘Relativity‘. This theory states that time and space are linked together. Einstein said that our universe has a speed limit: nothing can travel faster than the speed of light (299,792,458 meters per second).
How does this fit into time travel? Well, according to this theory, the faster you travel, the slower you experience time. Scientists have done some experiments to show that this is true.
For example, one experiment was conducted using two identically timed clocks. While one watch was on Earth, the other was put in an aeroplane and flown. (The plane also moves in the same direction as the Earth rotates).
After the plane flew around the world, scientists compared the times on the two clocks. Then the time of the clock on the fast-moving plane was slightly behind the time of the clock on the ground. So the aeroplane clock has been ticking at a rate of slightly less than 1 second per second.
Can we travel through time in everyday life?
We cannot use a time machine to travel hundreds of years into the past or the future. Such time travel only happens in books and movies. But the mathematics used in time travel directly or indirectly affects our daily lives.
For example, we use GPS technology nowadays to travel from one place to another. (Google Maps). NASA scientists use a very high degree of accuracy in GPS technology to determine where satellites are in space. But did you know that the GPS technology that helps you travel around the world relies on time travel calculations?
GPS satellites orbit the Earth at a speed of 14,000 kilometres per hour. This causes the GPS satellites’ clocks to slow down by a tiny fraction per second relative to Earth. (Same as the example of the aeroplane test mentioned above).
GPS satellites orbit the Earth at a speed of about 14,000 kilometres per hour. (Credit: GPS.gov)
Also, the satellites are travelling about 20,200 km above the Earth. Because of this, the clocks of GPS satellites actually move faster relative to Earth by a fraction of a second.
Here’s how it happens: According to Einstein’s theory, gravity bends space and time, slowing the passage of time. Earth’s gravity is very weak near the orbits of satellites. Because of this, clocks on GPS satellites run faster than clocks on Earth.
The overall result of both of these events is that the clocks on the GPS satellites experience time at a slightly faster rate than 1 second per second. Fortunately, today’s scientists can use mathematics to correct these differences.
If scientists do not fix these GPS clocks like this, we will face big problems. First, GPS satellites cannot accurately calculate their position or your position. Errors add up to a few kilometres each day, eventually adding up to a very large value. Then the GPS maps show your home, not where it actually is, but somewhere else far away!
In summary:
Yes, time travel is indeed a real thing. But not as you’ve often seen in movies. In some special cases, we can experience the passage of time with a very small change of less than 1 second per second. (Astrolearn.com)
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