Why Can’t We Invent a Time Machine?
Well, theoretically it IS possible to travel in time – but only forward, not backward in time.
So, here’s the thing – we can ‘appear’ to travel forward in time by travelling faster.
We can travel faster through time by changing our relative velocity or speed, an idea rooted in Einstein’s special theory of relativity (see our article So Why Does E=MC2 ?). To do so would require us to travel as close as possible to the speed of light, which is about 186,000 miles per second.
So far, the fastest humans have travelled is 7 miles per second, when astronauts were going to and coming back from the Moon. There’s a long way to go!
The faster you travel, the slower time moves relative to a stationary observer. Sirius, the Dog Star, the brightest star we see in the night sky, is about 9 light-years away.
If you traveled at 99.99999999% of the speed of light, the relativistic effects are 70,000 times normal :
- Mass increases by 70,000 times
- Time slows down by 70,000 times
- Length contracts by 70,000 times.
The Result : You could go to Sirius in the morning and get back late at night. You would be less than a day older, but everyone else on Earth would be 18 years older.
The good news is that there’s is no magic here ‘ no voodoo of any sort. The bad news however is that we simply have no way at the present time of getting to those speeds. (see our article “Why Can’t We Travel Faster than the Speed of Light”)
We Already Have a ‘kind of time-machine’
The Andromeda Galaxy may not even be there now, all we know is how it looked 2 million years ago
A telescope is a kind of time machine. It allows you to look into the past. If you observe the Andromeda Galaxy in the night sky then you are looking 2 million years into the past. The light that you see tonight left Andromeda 2 million years ago. The Andromeda Galaxy may not even be there now, all we know is how it looked 2 million years ago.
|So Why Does E=MC2 ?|
|Why Can’t We Travel Faster than the Speed of Light|
|What Causes the Pull of Gravity ?|