Why does time dilation work

As a person gets farther away from the surface of the earth — even just a few meters — the gravitational force on that person gets weaker. We don't notice it much as humans, but even going from the first floor of a building to the second floor of a building moves you away from the earth and therefore slightly weakens the gravitational force that you feel.

The difference in gravity between that felt at three meters above the surface of the earth and that felt at four meteres is too small to notice with our human senses, but the difference is large enough for sensitive machines to pick up. Because the strength of gravity is weakening with every step you take up a flight of stairs, the rate at which time proceeds is also speeding up with every step.

People who work on the bottom floor of a skyscraper are literally time traveling into the future compared to the people who work on the top floor. But the effect is very small. So small, in fact, that you will never notice the time difference in everyday life.

Once again, we visited the baffling realm of time dilation, and returned relatively unscathed. Once again, a big thanks to Dr. Koberlein for taking a few minutes out of his relativistic travel to answer our questions.

Make sure you visit his blog and read his answer to my question. Podcast audio : Download Duration: — 3. Podcast video : Download Duration: — I thought Time Dilation was that long, painful process that occurred before a new universe is born? Such as when something speeds up or when nearing a black hole, like in Interstellar?

Some supermassive black holes at the centre of galaxies are devouring the surrounding material. This artist's impression shows how the black hole accretes the surrounding matter through a disc orange.

Part of the accreted material is pushed away in a wind blue , which in turn powers a large-scale galactic outflow of molecular gas red. Time dilation is real! Interstellar actually did a remarkably good job of discussing time dilation in general, especially given how counter-intuitive ideas to do with relativity can be.

In Interstellar , the major plot points surrounding time dilation are the difference between time passing in two different locations, where the astronauts sitting near the black hole felt time passing at a slower rate than their families back home on Earth. Similarly, when some of them head down to the water world, they feel time passing at a slower rate than the astronaut left on the spacecraft.

The principle is this: the deeper you find yourself in a strong gravitational field, the slower your clock will run, relative to someone who is not in as strong a gravitational field. This can be translated into meaning the closer you are to something large, the slower your clocks will run.

However, it also means that if your two clocks are the same distance from two objects, one which has a much stronger gravitational pull than the other say, a planet for one clock, and a black hole for the other , the clock around the more massive object the black hole will run slower, even though both clocks are the same distance away. A light clock seems to be the best measure of time since its speed remains constant regardless of motion.

So in Fig 4, we walk up to the light clock and find that it takes 1 sec for the light to travel from the bottom to the top and back to the bottom again. Now look at Fig 5. In this example, the light clock is rolling to the right, but we are standing still. If we could see the light beam as the clock rolled past us, we would see the beam travel at angles to the plates. If you are confused, look at Fig 4 and you'll see that both the sent beam and received beam occur under the sun, thus the clock is not moving.

Now look at fig 5, the sent beam occurs under the sun, but the reflected beam returns when the clock is under the lightning bolt, thus the clock is rolling to the right. What is this telling us? We know that the clock standing still sends and receives at 1-second intervals.