We all know the first person to realize something strange when objects fell was Sir Isaac Newton. He began to see the pattern in nature and one of those patterns became his theory of gravity. The word gravity comes from an ancient word ‘gravitas’ which means ‘heavy’.
Gravity is about much more than a fallen apple – it withdraws the objects together in proportion to their mass and inversely related to the distance between them. The gravity is a law throughout the universe. However, understanding the gravitational force has expanded in many dimensions – some of the more complicated questions regrading gravitation is still far from settled.
You don’t need to worry about these unanswered questions. Instead, here are some theories, fun information and facts about gravity that you might not aware of. Now is a good time to enhance your knowledge.
Table of Contents
28. The Apple-Newton Story
In childhood, we all have been taught that apple fell on Newton’s head. Well, that’s not what exactly happened. Sir Isaac Newton was already aware that objects fall and gravitation was a universal feature of life on Earth. Witnessing and apple falling to the ground was the thing that first got him wondering about the very important thoughts – the apple must be falling towards the center of Earth. These thoughts were already in his mind, but watching the apple galvanized the concept in his mind palace.
27. The First Square Law
Image credit: wikipedia
F = G * (mM)/r2 is the first square law (by Newton) in science, which means object twice as far away exerts quarter of the gravitational force. It also means that the reach of gravitational pull is technically finite.
26. Gravity Has No Duality
Gravity always attracts, never repels. Anything with mass has its own gravity. Take an example of your computer and television, they both have their own gravitational force exerting on each other. You don’t see these stuff coming towards each other because the force exerted by them is too weak. However, the Earth is much larger and heavier (and more mass means more gravity), all your things are attracted to the center of Earth.
25. The Urge To Pee In Space
On Earth, we usually get urge to pee when bladder is 1/3 full. But in microgravity, the urge doesn’t kick in till the bladder is almost full.
24. What If Sun Disappeared (in terms of gravity propagation)?
If the Sun suddenly vanished the Earth would not fly off immediately, it would continue to orbit what should have been in the position of Sun for 8 minutes, before flying off tangentially. In the same way, Earth actually continues to experience gravity from stars that are long gone.
23. Gravity Pulls Everything At The Same Rate
The gravitational force on the surface of Earth accelerates every object at the same rate, regardless of its weight. If you drop a feather and a bowling ball in vacuum from a certain height, they would smack the ground at the same time.
22. Food Doesn’t Taste Same In Space
Image credit: NASA
In space, there is no gravity to pull down fluids – astronaut’s sinuses get clogged up and they can’t really taste much of anything.
Astronauts do not consume carbonated drinks because in space it is hard to separate the liquid and gas in stomach which leads to ‘wet burp’ (similar to vomiting).
21. Different Planet, Different Weight
The effect of gravity is not same on every planet in our solar system. A 68 Kg person would weigh 4.5 Kg on Pluto. On the other hand, the planet with highest gravitational force is Jupiter, where the same person would weigh around 160.5 Kg.
Moreover, on Saturn’s moon Titan, the atmosphere is so thick and the gravitational force is too weak that humans could fly through it by just flapping ‘wings’ attached to the arms.
20. Gravity is Uneven
Our globe isn’t a perfect sphere, its mass is distributed unevenly. And because the gravity depends on mass, the gravitational force isn’t same on entire Earth.
The Hudson Bay region (in Canada) has lower gravity (because of melted glaciers) than other regions.
19. Gravity Is Too Weak
There are 4 types of forces in the universe – gravitational, electromagnetic, weak nuclear and strong nuclear force. Gravity is the weakest one.
A dime-size magnet has enough electromagnetic force to overcome the entire Earth’s gravitational force and stick to your oven.
18. Einstein’s view of Gravity
Einstein gave a whole new concept of gravity. His general theory of relativity was the first to treat gravity as a space-time distortion. He described space-time as a “fabric” that physically embodies the universe. Anything with a mass wraps the space-time around it.
On May 2011, Gravity Probe B experiment done by NASA, proved that the Earth pulls the universe around it like a wooden ball spinning in molasses. The is exactly what Einstein predicted back in 1915.
17. Gravity Can Bend Light
Massive objects cause space-time distortion and they also sometimes bend the light that passes through it, just a glass lens does. This effect is called gravitational lensing and amount of bending is one of the prediction of general theory of relativity.
Along with the light, gravity also affects time. A pendulum clock accurate at sea level loses approx 16 seconds every day if it is taken to an altitude of 4000 feet.
16. Neutron Star
A Neutron star is very dense and small (about 20 kilometers diameter) star, made almost completely of neutrons. Because of its strong gravitational force, the tallest possible mountain there can only be about 5 millimeters. The gravity even bends the radiation emitted by the star such that a portion of the invisible rear surface becomes visible.
15. Our Perception of Gravity
The research paper published on journal PLoS ONE says that we are better at judging how objects fall when we are sitting upright versus lying on our sides. The brain depends solely on visual heuristics. The objects appear more stable than they are when the head is tilted in the exact same direction in which they fall.
14. The Escape Velocity
How fast you should throw an object so that it never comes back to Earth? To leave the Earth’s gravitational pull behind, you need to throw it at the speed of 11.2 km per second or 40,270 km per hour.
The escape velocity of the moon is 2.38 km per second and for Jupiter it is 59.5 km per second.
13. Lagrangian Points
Image credit: wikipedia
There are regions in space between Earth and Sun (or any two massive bodies) that creates Lagrange Points. The other body can orbit around these points as if there was something there.
There are 5 such points labeled L1 to L5. The first 3 points are on the lines connecting the 2 planets and last 2 (stable points) form an equilateral triangle with 2 planets.
12. Jupiter Power
Jupiter’s gravity will eventually cause Mercury to eject from the solar system or crash into the Sun. Moreover, it is strong enough to tear asteroids apart and capture 64 moons (at least).
11. The Microgravity
The astronaut on the International Space Station and passengers on Amusement park rides feel microgravity (not zero gravity) because they fell at the same speed as the vehicle.
10. Gravity in Space
There is a big misconception about the role of the gravity in space. People often refer to space as a ‘zero gravity’ environment.
The smallest amount of gravity can be found everywhere in space. International Space Station (ISS) orbits Earth at the height of around 400 kilometers. At the height, Earth’s gravity is 90% of what it is on the surface. That means a 100 kg person would weigh 90 kg on ISS.
If there is 90% gravity on ISS, then why do astronauts and things around them float there? That is because they are in free fall. They are falling towards but around Earth (at the speed of 28164 km per hour).
9. You Can Lose Mass Without Gravity
According to NASA, in the absence of gravity, muscles atrophy and bones lose bone mass. An astronaut can lose 1 percent of his mass per month in space. Their body and mind need time to recover after returning from space. The blood pressure (equalized throughout the body in space) needs to return to an Earthly pattern in which the heart works to keep the brain nourished with blood.
8. Some Bacteria Becomes More Deadly in Less Gravity
A few bugs become more nastier in space. A paper published on PNAS (in 2007) says that a bacteria named salmonella (which commonly causes food poisoning) becomes 3 times more injurious in less gravity. So there are not only space bugs to infect you, your own bugs grown inside would strike you.
7. Crystal Grows Better In Microgravity
Gravity doesn’t only affect living things. It has been found that the crystal grows much better in microgravity and their shapes are more perfect. Using acoustic waves, Japanese researchers have successfully grown a helium crystal in a microgravity environment. This opens an opportunity to study the dynamics of how such crystals form in a short time span.
6. Flames Are More Round In Less Gravity Environment
Because of microgravity, the air inside doesn’t get pulled up or down. It remains stationary (for astronaut sitting inside the free falling ISS). When the candle is lighten, the air near the wick heats up and because there is no cold air below the candle, it doesn’t rise. No air rising means no wax vapors rising, which makes the flame quite spherical in shape.
5. The Three Body Problem
The three-body problem is a sort of abstract puzzle that has made the scientists confused for 300 years. The problem is finding all the paths/patterns that three objects orbiting each other could take if influenced by only gravity.
So far, 16 families of solutions have been found; 13 of them were discovered in March 2013.
4. Humans Can Withstand 3 Times Earth Gravity
In the future, humans could colonize and live on other planets with 2 and even 3 times Earth’s gravity. However, at 4 times, we would no longer be able to sustain sufficient blood flow to the brain.
3. Tractor beam
NASA is trying to develop a device called tractor beam, which would have the ability to attract one object to another from a distance. It is based on the use of biaxial birefringent media. In fact, they have had some success on microscopic level.
2. Gravitational Waves
Image credit: NASA
In order to explore and understand the concept of gravity better, researchers are working on gravitational waves, predicted by Einstein in 1916. It’s a ripple in space-time, travelling outwards from a source. According to Amber Stuver, a physicist at Louisiana’s Laser Interferometer Gravitational-Wave Observatory (LIGO), these gravitational waves are generated from star explosion and black hole collision.
1. Black Hole
With the enormous gravitational force, black holes are the most destructive things in our galaxy. There is a monster named Sagittarius A*, containing 4 million times the mass of Sun, in the center of the Milky Way galaxy. It sent out a flare of energy 300 years ago.