The sky is blue. 2+2=4. There are some things we
Gravity: it’s all around us, pulling on us every moment of our lives. This, like many forces that people have discovered, has its own little quirks, and we have odd quirks in how we interact with it as well.
There is a speed of gravity
In 2012, a research team took measurements of the lag between the rotation of Earth’s tides and the rotation of the moon. They found that the tides follow slightly behind – their findings seem to confirm what scientists have surmised for a few hundred years – that gravity travels at the speed of light.
Gravity bends light
Well, sort of. According to the theory of general relativity, light actually continues in a straight line. Instead, gravity bends space-time around it, giving the appearance of light bending.
Your body depends on gravity
Being an astronaut has a lot of problems. Some of the most serious of these have to do with the astronauts’ bodies, which were designed with gravity in mind. First of all, gravity pulls down on your spine – in a gravity-less situation, a person gets taller. Then, your digestive system is used to gravity: without it, you get some crazy heartburn. Your cardiovascular system takes it easy in space, since it takes no more energy to pump blood to your brain than to your foot. Once the astronaut returns to Earth, the heart has to work hard to keep up the blood pressure in the astronaut’s brain, causing possible blackouts and fainting. The weird problem, though, is about bones. Doctors estimate that astronauts lose about one percent of bone mass each month.
Plants can sense gravity
A plant that grows upwards, when knocked on its side, will change the direction of its growth so that it once again grows up. This is achieved by particles in plant cells which fall to the bottom of the cells (In zero gravity, plants just grow every which way).
Gravity goes down with altitude
Gravity strength is partly dependent on proximity. So, it follows that the farther away from the center of gravity (or center of the Earth) a person is, the less gravity there is to pull on them.
You can judge gravity better while upright
According to a study from 2011 in the journal PloS ONE, people don’t judge how objects fall as well while lying on their sides. This means that our perception of gravity is less based on visual cues and is more based on body orientation.
Earth’s gravity isn’t uniform
The other part of the gravity equation is the mass of the attracting objects. Since Earth’s mass isn’t uniform, Earth’s gravity isn’t either. For example, there is oddly low gravity in the Hudson Bay of Canada, probably due to the now melted glaciers which pushed large amounts of Earth’s mass away from the area.
Some bacteria gets stronger without gravity
A 2007 study from the Proceedings of the National Academy of Sciences found that salmonella is three times more virulent in the tiny gravity in space. Something about the near-weightless environment changed how the bacteria operated and made it much, much worse.
There are black holes at the center of galaxies
That includes ours. At the center of the Milky Way is a humongous black hole – it contains the mass of 3 million suns. The good news about our black hole is that it is very unlikely to do anything to us: we are very far away, and it only rarely sends out flares.