Albert Einstein was one of the brightest minds our species has ever produced. During his life, he revolutionized our understanding of physics and the mechanics of the universe at large. Einstein showed that time itself is a relative concept and that objects experience time differently depending on their relative speeds. This means that time moves more slowly if you’re going faster.
For example, let’s say that I’m standing still and you’re driving in circles around me with your car. Time is actually moving more slowly for you than it is for me because your speed is faster than my own. This is not a trick of the eye or a weakness of the mind. It really happens. It is a phenomenon that Einstein referred to as “time dilation.”
Time dilation is a fascinating concept that helps uphold a fundamental law of our universe: nothing can travel faster than light. As something moves faster, it becomes heavier and requires more energy to keep speeding up. Additionally, time itself slows down for the fast-moving object compared to those moving slower. For instance, clocks on satellites, which move faster than those on Earth's surface, also run slightly slower due to their speed. This supports Einstein's theory and shows how time dilation affects objects moving at different speeds in our universe.
So what does time dilation have to do with immortality? Suppose that today, you find out you have a form of cancer for which we currently have no treatment. You’re given an estimate of only a few years to live.
If you had a near-light-speed spaceship standing by, you could climb aboard, spend a year traveling around the Earth at 99.99% light speed. Then you could return in 71 years (on Earth) to ask whether a cure for your disease had been found. Is there no cure yet? No problem. Get back in your spaceship and set the rate at 99.9999% light speed, where six more months would get you 350 more years of progress back on Earth. The discovery of cures for almost every disease is believed by many experts to be an inevitable eventuality given enough time. And with near-light-speed travel, time is something that you would have in almost infinite supply.
But what about the cost? The unfortunate catch to traveling centuries into the future via time dilation is that everyone you knew and cared about would obviously be long dead when you returned. You might be tempted to try to take some of your closest friends and family with you, but would they agree to make that sacrifice, leaving behind all others that they care about? Maybe everyone wants to board the spaceship to immortality, but someone has to stay behind and do the work so that the time travelers can benefit from it in the future. The pursuit of everlasting life might require unthinkable psychological pain and loneliness.
For better or worse, we haven’t quite worked out the mechanics of near-light-speed travel yet, so this question is more of a thought experiment than a realistic dilemma for now. But it’s worth keeping in mind that nothing in the laws of physics prevents us from achieving this feat eventually. So, one must ultimately consider, in light of the costs: Would immortality be worth it?