Albert Einstein’s general theory of relativity comes up once again, showing just how many revolutionary scientific discoveries Einstein was responsible for.
General relativity states that time dilation must exist due to the nature of spacetime‒a theoretical model of the universe that “fuses” our three spatial dimensions with time. Einstein discovered that objects that experience greater amounts of gravity observe time slower compared to an object that has weaker gravitational forces acting upon it. Similarly, an object that is travelling with a greater velocity will observe time slower compared to an object travelling more slowly. While the results of time dilation are only really noticeable when velocities or gravitational forces on two different objects are incredibly dissimilar, time dilation still occurs when there is only a small disparity. Meaning that you are technically experiencing time just a tiny bit slower when driving down the highway compared to when you are sitting at your computer. In fact, it is possible to determine just how much slower you are experiencing time when travelling at a certain velocity compared to being at rest
The equation to determine time dilation is in picture 1 where t is the time that an observer with a velocity experiences, t0 is the time that the initial observer experiences, v is the speed of the object that is moving, and c is the velocity of light in a vacuum, which is a constant (2.99 x 108 m/s). So let’s say you are traveling in your car at 90 miles per hour on the highway, because who actually goes the speed limit? But, your buddy Albert is sitting down in his lab with virtually no velocity. Then, to figure out how much slower one second of time is for you travelling at 90 miles per hour, we must use the equation above. So, t0 = 1 s, c = 2.99 x 108 m/s, and v= 90 mi/h = 0.025 mi/s = 40.234 m/s. Therefore, our equation is picture 2= 1.0000000000000090057 s. This means that for every one second passing in the car, 1.0000000000000090057 seconds pass for Albert. Huge difference, I know. However, as stated before, time dilation becomes incredibly apparent at great speeds and when gravity is extremely different for two objects. If you were to turn on the turbos in your car and somehow manage to travel at 200,000,000 m/s instead of 40.234 m/s, then t = 1.3423847008414 s. That might not seem like a great difference, but if you were to travel in the car going 200,000,000 m/s for 3 years while Albert remained stationary, then approximately 4 years would have passed for Albert!
What is even more interesting is that time seems completely normal for both you and Albert. From your point of view, only 3 years has passed and those 3 years actually feel like 3 years. Whereas for Albert, it actually feels like 4 years has passed. So what would happen if you were to slow down back to a velocity of 0 m/s? If you and Albert were the exact same age prior to this little experiment, then you would now be 1 year younger than he is, as you only experienced 3 years of time while he experienced 4. Sounds crazy huh? Even more mindblowing is that as an object approaches the speed of light, time begins to slow so greatly that it almost is not even passing and that at the speed of light, there is theoretically an infinite amount of time passing around it. Just use the equation above: is picture 3 = picture 4= ∞ s. So...if an object were to theoretically travel at the speed of light, then it would experience no time passing...so essentially the entire surroundings of an object travelling at the speed of light would age infinitely instantaneously until the universe dies, while the object itself doesn’t age at all. Yay!
Note to self: never ever try to travel at the speed of light.
“Hold on a minute…” you say dazed and confused, “Does that mean that light does not experience time?” Correctomundo. A photon could exist for billions of years from our perspectives, yet from the photon’s perspective, it literally experiences no time. As you can see, the world of physics is literally mind blowing. It is hard to believe some of this stuff, yet the math checks out. So, don’t believe any of those commercials that claim they sell “anti-aging” products as the only real way to prevent aging is to travel extremely fast or cross the event horizon of a black hole. Your choice.