 Here's a famous question. If the Sun were to suddenly disappear, how long would it take us to know? Obviously, it would take us 8 minutes for our eyes to notice the difference since that's how long it takes light from the Sun to reach Earth. But what about gravity? After all, the Sun's gravitational exertion does play a huge role in anchoring our solar system together, so the absence of a Sun would be felt by all of us when the orbit of our planet went out of whack. But the question is how long would it take us to feel it? Would we feel the effects instantly or would it take some time? Stick around to find out. In 1687, Isaac Newton published his Principia Mathematica. In it, he laid out his views on space, time, and gravity, stating that space and time are two separate entities and that gravity was something innate in an object that acted over any distance instantaneously. A couple of hundred years later, Albert Einstein then came along, claiming that space and time were actually one entity and that they were interwoven together in this sort of fabric that permeated the universe called spacetime. Moreover, Einstein believed that the presence of matter and energy could curve the fabric of spacetime and that it was this warping of spacetime that we perceive as gravity. So, do we have proof of Einstein's claim? Well, in 2004, we launched Gravity Probe B, a spacecraft which had four gyroscopes. Should Einstein's theory be true, Gravity Probe B's four gyroscopes would have minute changes in the direction of their spin as Earth's gravity tugged at the spacecraft as it spun. If Einstein was wrong, however, then the gyroscopes would continue to be pointed in the same direction. Fortunately for Einstein, the gyroscopes did have a detectable direction change, establishing a link between gravity and the warping of spacetime. But it doesn't end there. Einstein's theory also states that gravity isn't an instantaneous force, but rather gravity actually travels at the speed of light in a vacuum. This can be a little confusing to understand, so let's use an example. Let's say we had a ball about half the size of Earth. With the size and mass that large, it would warp the fabric of spacetime by a considerable amount. Now, let's say this ball suddenly disappeared. What would happen next? Well, obviously the warp space would go back to its normal shape, but not at every point at same time. The space returns to being normal at a central point, which then sends out disturbances like ripples in a pond. These disturbances in spacetime called gravitational waves travel out at the speed of light. So now that we have a better understanding of what gravity is and how fast it travels, we have some clue to what our answer is to the disappearing sun question. It would take eight minutes for us to feel the effects of the sun's disappearance as the sudden removal of our sun would send out gravitational waves rippling through the fabric of spacetime at the speed of light, which would eventually reach our Earth. But what would happen when those gravitational waves did reach our Earth? Well, gravitational waves have hit the Earth, and we have even been able to detect and measure them. But if space really is wobbling around like waves in the ocean, which you can generally feel, why don't we feel gravitational waves whenever they hit Earth? Well, spoiler alert, it's because this phenomenon is incredibly quick and tiny. But what I think really makes this interesting is how we were able to detect them, and the links at the team at the laser interferometer Gravitational Wave Observatory, or LIGO, had to go in order to actually get these results. If that also interests you, head over to my channel, Canubis, to learn more about this. It will absolutely blow your mind as to how much care and precision went into this. And of course, be sure to subscribe to both our channels.