We have all experienced the force of gravity. It is what happens to you when you jump up into the air, and fall right back down to the ground. But have you ever wondered: What if there was no gravity? What exactly would life on earth be like?
Jay Buckey, a physician and one-time NASA astronaut, explored how the absence of gravity affects the human body. Buckey says that our bodies are adapted to the gravitational environment on Earth, such that if we spend time living where gravity is different, such as on board a space station, our bodies change. It is now an established fact that astronauts lose bone mass and muscle strength during their short stay in space (usually about 6 months at a time), and their sense of balance changes.
An absence of gravity brings other problems. For reasons not entirely clear, our red blood cell count falls, bringing on a form of space anaemia. Wounds take longer to heal, and the immune system loses its strength, even sleep is disturbed if gravity is weak or absent. And this is just what happens after a short visit to space! What about the systems that depend on gravity? Such things like your muscles, your balance system, or your heart and blood vessels, the earth’s atmosphere and its oceans, rivers and lakes?
Karen Masters, an astronomer at the University of Portsmouth in the UK, says the first problem is that Earth which is rotating at high speed – similar to the way a weight on a string rotates if you spin it around your head – will simply be thrown off balance, similar to what will happen to the weight mentioned earlier if the string is cut. And things not attached to the Earth in any other way would fly off into space, taking them away from the surface of the Earth.
Anyone unfortunate enough to be outside at the time would quickly be lost. People inside buildings would be safer, because most buildings are so firmly rooted to the ground that they would stay put even without gravity – but only for a while. Anything else not nailed down would also float off, including the earth’s atmosphere and its oceans; rivers and lakes would be one of the first things to drift away into space.
Eventually the lack of gravity would eventually take its toll on our planet, reducing it to clumps of matter, including stars and planets and pretty much everything in the Universe. Something similar will also happen to the Sun, because without the force of gravity to hold it together, the intense pressures at its core would cause it to burst open and explode. The same thing would happen to all the other stars in the Universe; however, because they are so far away, it would be years before the light from their death reaches us.
After this, the inevitable will happen and we would all die! Eventually there would be no clumps of matter, like stars or planets, anywhere in the Universe. There would just be a mixed soup of atoms and molecules, drifting around not doing anything much.
Though the scenario painted thus can NEVER happen, it just helps to illustrate how fundamental gravity is to the workings of the Universe. Without it, nothing interesting like planets or life could ever exist.
See Also: BBC Earth
