OK so I know this has been asked but I still don’t get it.
Who do humans age faster/slower? (Shown in interstellar for example) Biologically I don’t understand why the body would age faster?
In: 36
The answer you are looking for is general relativity, which can be summarized as: the closer you are to massive objects with heavy gravity (planets, stars, black holes) the slower time will pass for you compared to someone farther away. Time is not a universal constant. Instead, every person, every object has a different time. Because we, as people, live in mostly the same conditions as every other person, all on the same planet orbiting the same sun, our times are so similar that there is no point in making any distinction between my time and your time. Even astronauts in space have a difference of less than a nanosecond. However, in science fiction stories, we can imagine scenarios where people live in places that are distinct enough to have times that are different enough to compare, introducing time dilation.
You mentioned time dilation in the movie Interstellar. When the crew visits a water planet, that planet is orbiting close to a black hole, and left one person on the main ship far away from the black hole. The crew near the black hole, because of how massive the black hole is, experience time passing much slower for them than the person on the ship far away from the black hole, or the people back on Earth who are also not near a black hole.
You can imagine this as a game which is lagging on your PC. Normally the game proceeds at the same speed as you sitting in your chair, with one second passing for you and one second passing in the game, but imagine the game starts to lag. Then everything in the game will slow down as your computer cannot simulate what normally happens in one second, and it will instead take three or four seconds from your perspective. While four seconds passed for you, only one second passed in the game. This is an approximation of what watching someone go near a black hole would be like. You are the observer, hanging out far away from the black hole, while your game took a detour near the black hole and experienced time dilation. If your game was growing crops, even if the game says your crops grow every ten seconds, for you it would look like forty seconds because of lag.
Imagine you and me both have identical 100% accurate stopwatches, and you start the at the exact same time standing next to each other on earth.
If you now start to move very very fast, away from the earth (for example in a rocket ship), and come back after 1000 hours passed on your stop watch, and return to earth after 2000 hours passed on your stop watch, only 1200 hours would’ve passed on my stopwatch.
Even though the stopwatches were both identical, and use the same mechanism, you’ve experienced 2000hrs, whilst only 1200 hours have passed for me- even though we’re now next to each other- you’ve had 800hrs of life I haven’t had, your stopwatch for 800hrs I never had, but as did your cells and body. We could’ve been twins, but now you’re 800hours older
Time itself runs at a different speed.
Imagine you had some kind of magic time slowing chamber where inside it time runs 10x slower. Anyone getting in to it would look from the outside to be moving in super slow motion, and to the person in the chamber everyone outside would be moving in super fast motion.
If the person inside stayed in there for a year of their time, 10 years would have passed outside.
Now these time chambers kind of exist, anything moving close to the speed of light or in a very strong gravity field will experience slow time like this.
That’s what happened to the crew in Interstellar, they were in a very strong gravity field so time was running slower for them.
From the questions here in the last week makes me think a ton of people just discovered the Foundation series 😅
Its not like the cells age faster or slower. Time itself is bent an´d stretched. imagine a car that travels across a flat piece of land versus a car that drives over amountain.
Imagine both cars having to travel 1kilometer as the crow flies. however due to the “dilation” of the mountainous road into another dimension, the car has to physically travel more way for the seemingly same “distance”
Answer: Rather than a complicated answer you can do a thought experiment to understand time dilation and from there you’ll understand how it affects you.
So imagine you’re on a train moving REALLY fast, like, Japanese Shinkansen fast. And while you’re on the train moving really fast, you point a torch out the window and move it 1m up, then 1m down, up and down and up and down. From your perspective the torch just goes up and down and if we say it takes 1s each way, we’d say it’s moving up and down at 1m/s, right?
So now imagine you’re a bystander, standing on the side of the tracks when the train goes past and watching the torch go up and down. From the bystanders perspective the torch goes up and down but it’s also moving sideways so it makes a diagonal zig zag path; But remember for the person on the train it’s going up and down, not zig zagging!
This means that the bystander watching the torch follow its zig zag path, has watched the torch cover more distance but because it wasn’t going any faster and as far as they could tell, it took the same amount of time, that leaves time as the only variable that could have changed because the people in our thought experiment experienced it differently. And that’s how we prove time dilation exists.
As far as each person is concerned, time stays the same for them, but if a bystander is looking at them, the bystander will see the first person cover more distance without going faster which they can only do if time has slowed down to allow them more “time” to cover that extra distance. Time has dilated.
Imagine yourself running on a big flat surface. You have some maximum speed you can achieve and let’s assume you don’t get tired (it’s constant). If you choose to run north, then your speed towards north is your max speed. Easy, right? If you choose to run west, your speed towards west is your max speed and your speed towards north is zero. Now, if you choose to run north-west, then your speed towards north is not going to be your max speed, because you’re also assigning a portion of your speed to go towards west as well, and the more towards north you direct yourself, the more “west speed” you’re going to sacrifice, bringing your “north speed” close to your maximum (and vice versa if you decide to go more west). Does this make sense?
If yes, then simply imagine moving through time is also a direction that contributes to using up your maximum speed. So if you don’t move too fast physically, you move through time at “normal rate”. But if you go really, really fast in any physical direction, you sacrifice your speed of moving through time – which is why you’d be younger than those who didn’t go as fast.
Everyone’s body ages exactly the same way at exactly the same speed.
What’s different is that time isn’t actually a universal thing that we all agree on. It passes for each person completely independently of everyone else.
Space and time are basically the same thing. Think of *c* as the *conversion factor* between space and time. Everyone that’s sitting still together is moving forward through time together at the same speed. But if you accelerate so that you are moving fast relative to everyone else, from their perspective you have traded some “speed” in time for your speed in space. From your perspective, after you have accelerated, you perceive yourself to be still in space again, and are still moving forward in time at the speed you will always move. But from their perspective you are now moving slower in time because you are moving faster in space.
It’s also important to point out that there are two kinds of time dilation: special relativity (caused by the difference in speeds, where both observers see each other’s clocks ticking more slowly only as a result of the difference in perspectives), and general relativity (caused by spacetime curvature and accelerations, where the effects aren’t symmetric), but it’s much harder to ELI5 these.
A few good accurate answers are up so I’ll try one that’s more ELI5:
If you need to drive from your house to the store, there are probably multiple paths you can take. So you and a friend can get into your cars and drive to the store and then compare odometer readings: maybe you took 2 miles and your friend took 3 miles to get there. We’re used to that: different paths through space can have different lengths in space but still meet each other.
What special and general relativity add is that when getting from one point in space and time to another point in space and time, your path can have a different “length” in time too.
So you and your friend can get into your spaceships and travel to a different planet taking different paths in space-time, arrive simultaneously, and compare odometer and clock readings and maybe your clock advanced by 6 years and your friend’s advanced by 7.
It’s not anything special about aging or human bodies. It’s that when objects move relative to each other or are subjected to different amounts of gravity (like being closer to a black hole in the case of Interstellar), they take different or lengths of paths through time.
There isn’t a central clock for the universe. Time moves at different speeds in different places, depending on gravity and closeness to the speed of light.
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