Gravity, Just an Illusion?

Legend has it that during the 17th century, Sir Isaac Newton observed an apple falling from a tree and began to wonder why the fruit had fallen to the ground instead of upwards or sideways (which would have been quite strange).

After years of studying, he concluded that gravity was responsible. Scientists called it a force of attraction that existed between all objects. However, it was many years later that Albert Einstein revolutionized these ideas about gravity.

Legend also has it that Einstein was not completely satisfied with Newton's findings; something just didn't seem right. As a young scientist, Einstein had some trouble formulating his theories while trying to explain the behavior of moving objects. Then an experiment came to mind, which he called "the happiest of thoughts," and he realized that gravity feels like the sensation of writing in an ascending elevator. He called this theory "general relativity."

Einstein worked tirelessly to prove his theory, and at one point, he even complained that he was on the brink of losing his mind.

In the simplest terms, general relativity proposes that gravity is the curvature or warping of space. The greater the mass an object has, the more it warps the space around it. Imagine a heavy ball resting on a trampoline; the rubber sheet underneath gets warped under its weight. It's the same with our sun.

It's big enough to twist space across the entire solar system, and that's why our planet, as well as all the others, orbit around the star. This warping also affects how we measure time. If you look at your watch, time seems to go by at the same rate every day.

However, if you hike to the top of a mountain, and your friend wanders through a valley at the bottom of the mountain, you'll notice that your watches will calculate time differently. One watch will tick faster, while the hands of the second one, which is traveling through the valley, will move more slowly

That's because gravity affects how fast time goes by. With these experiments in mind, Einstein's theory of general relativity was a groundbreaking discovery.

Einstein concluded that gravity was not a force of attraction, but rather a curvature in the fabric of space-time. We feel gravity as a force simply because we're placed on some surface. If there was no surface and no attraction between us and this surface, we would become weightless.

If you don't mind getting some weird looks, try this experiment: you'll need a bathroom scale and an elevator to ride. You'll soon see that your weight fluctuates as you move up and down the elevator.

As you move up and down in the building in the elevator, the gravitational force is the same, but your weight is different because the elevator speeds up and slows down. Aboard the International Space Station, astronauts literally move along with the station, so there's nothing to push them against the side of the station, and they have no weight.

Even if we still think of gravity as a force, it's the weakest one we know. First of all, it only attracts; there's no negative counterpart that could push things away. And weirdly, even though this force is strong enough to keep galaxies together, we still overcome it every day. Every time you lift an object off the floor, you overcome the force of gravity produced by the entire Earth.

Just to paint a better picture, Earth's gravitational pull is weaker than the power of a refrigerator magnet. The fact that our planet has gravity also affects the way we look and act. All creatures on Earth are limited in growth by the height of their skeleton and by how much weight it can carry, which is directly proportional to gravity. That's why some marine creatures can grow bigger. The largest animal on our planet right now is the Antarctic blue whale. It's about the size of two school buses combined because sea creatures can float, which slightly counteracts gravity.

The effects of gravity can be seen in many aspects of our daily lives, from the way we move to the way we grow. Despite being the weakest force, it plays a crucial role in shaping our universe.

As people too, we are taller in the morning than we are in the evening. Our everyday activities and the added effect of gravity make the cartilage in our ankles, knees, hips, back, and neck compress. Once you have overnight rest, the cartilage swells back to normal.

Gravity might also affect your shower routine, that is if you're an astronaut. They have to rely on the old-fashioned way of bathing up there on the space station because they can't take a shower since the force of gravity up there is different, and water doesn't flow as it should. Instead, they use liquid soap, water, and no rinse shampoo.

First, they squeeze some liquid soap and water from pre-made water pouches onto their skin. Next, they open the no-rinse shampoo and add a little water to wash their hair. Towels are then used to wipe off the excess water, which is really precious in space. To make sure they recycle it, an airflow system quickly evaporates excess water.

Gravity and weight shouldn't be confused. Astronauts on the space station do float, and you may sometimes hear that they are in the state of zero gravity

It's far from the truth, though, since gravity up there is about 90 percent of its value on our planet. But astronauts look and feel weightless since weight is the force a certain object exerts on them. Back on Earth, most creatures have evolved to sense and adapt to Earth's gravitational pull.

In the sea, for instance, some fish have floating calcium carbonate deposits in their heads. Scientists call them ear stones, and they're pulled down by gravity. They act like a fish's internal compass. Plants have evolved to grow starch grains in the tips of their roots. They use this amazing feature to force their roots deep down into the soil.

As little as we seem to understand it these days, we do need gravity for way more things than we can imagine. For instance, some bacteria become even more dangerous in space where there's little to no gravity. Salmonella, for example, the type of bacteria that is known to cause food poisoning, becomes three times nastier in the condition of microgravity. So you really gotta cook your chicken.

Our own Moon stays where it is because of the effects of gravity, too. If it weren't for this force, our satellite would have floated away by now. But it's held in place by Earth's gravitational pull. Objects with the biggest gravitational pulls in the universe are black holes. Thankfully, our planet is really far away from any of them. Nothing can escape the gravitational pull of a black hole, not even light itself.

Similarly, gravity is different on each planet, and because of that, things weigh differently depending on which planet they're on. Take Earth, for example. An object that weighs 100 pounds here would only be 38 pounds on Mercury. But if you're planning on losing weight fast, try booking a trip to Pluto. Someone who weighs 150 pounds on Earth would weigh no more than 10 pounds on Pluto. The same person would weigh considerably more on Jupiter, which is the planet with the most powerful gravity. 150 pounds on Earth would turn into more than 354 pounds there.

Remember that experiment with watches ticking at different levels of elevation? It turns out that gravity isn't spread evenly on the surface of Earth. Why? Because our planet isn't a perfect sphere. The mass of Earth isn't evenly distributed either. That's why you get variations in gravity in different locations. Moreover, gravity is weaker at the equator because of the centrifugal forces produced by the planet's rotation.

Since we've always perceived gravity as a force, we seem to believe that it has somewhat of a suction motion, but it's not exactly true. Back in 1998, scientists were baffled to see that the expansion of the universe was speeding up. So they linked this to the repulsive gravity of mysterious Dark Energy. We now know that dark energy makes up for more than 60 percent of the mass-energy of our whole universe. But since nobody knows what it actually is, we can only make assumptions. And one that is largely accepted is quantum theory, which seems to claim that gravity pushes rather than pulls things in.

So yes, to summarise, gravity is a complex topic, and there's a lot to understand about it. But I'm here to answer any questions you may have!