Pretty cool eh? This scenario is known as the Twin Paradox. Effectively, we would have sped through to the future quicker than everyone else, simply by moving very fast. We would have aged by ten years, but everyone else on Earth would have aged by 71 years in the mean time! If we return to Earth after ten years at this speed, we’d be shocked to find that time had travelled at a different rate for us compared to people left on Earth. Well, let’s imagine we can board a rocket and fly out amongst the stars for ten years, travelling at 99% the speed of light (never mind that we don’t actually have the technology to do this yet). Interesting.įor more details on relativity, watch this video narrated by our very own National Space Academy director Anu Ojha. The light in the moving clock appears to travel a longer distance between mirrors, meaning the ticks of the clock are slower. Grab a ruler or a bit of string to measure the length of the path that the light travels from the bottom mirror to the top mirror, for both the stationary light clock image and the moving light clock image. The path the light would travel would look something like the second image on the left. Imagine watching this clock as an observer on the ground as it speeds past. Could be a skateboard, could be a rocket. Now imagine we put this light clock on moving vehicle. So let’s build a clock from a beam of light bouncing back and forth between two mirrors, ticking out constant intervals of time forever (see top image on the left). What do we know that always travels at exactly a constant speed no matter what? Light! The speed of light is constant. But we do need something that can tick out time at exactly a constant rate. We don’t have to count in seconds or minutes. So how can a clock be slowed? Well to show you that, I first need to build a clock. įor those of you who are anxiously awaiting the possibilities of time travel, don’t worry we’re nearly there! Because if we can speed up or slow down a clock, then we can move into the future faster or slower than other people, effectively travelling in time. But to their surprise, the speed of light was always the same, regardless of the speed of the observer. In 1887, two American scientists tried to measure the speed of light relative to the motion of the Earth, hoping to find different apparent speeds. Someone standing on the side of road would measure each car as travelling 100 kilometres an hour. Because of your combined speeds, the other car will appear to be speeding towards you at 200 kilometres an hour. Imagine you’re driving down a dual carriageway at 100 kilometres an hour and you measure the speed of the car approaching from the opposite direction, also driving at 100 kilometres an hour. This is definitely not true for other moving objects. 300,000 kilometres per second to be precise.Īs well as a speed limit, Einstein also suspected that the speed of light was the same for all observers. But make careful measurements of light across large distances (as Ole Rømer did in the 1670s when he studied light travelling between Jupiter and Earth) and it becomes clear that light does have a speed limit, it just travels really, really, really fast.
Switch a lamp on and immediately we see light, with no noticeable delay. In every day experiences, light seems to travel instantaneously across a room. But then a young patent clerk by the name of Albert Einstein astonished the world by publishing a theory of space and time with rather bizarre consequences.Įinstein began by considering the speed of light. So, how can I travel forward in time, you ask?īefore 1905, we would have said that any kind of time travel was most definitely in the realm of science fiction.
0 kommentar(er)
