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### Gravity is Really Weak?

 In these lessons I send out to you all I throw out ideas such as: "gravity is really weak". Well, what exactly do I mean by "really weak"? Is there a scale to all these ideas?

Physicists know about 4 fundamental forces. Two of them, the strong and weak nuclear forces, have to do with holding together the nucleus (the lump in the middle made from Protons and Neutrons) of a atom. These 2 forces are important to how the Universe runs and how stars shine but you never see them working out here in the "real" world. The other 2 forces are Gravity and Electromagnetism. Everything you and I know about the world we live in is from these 2 forces. Electromagnetism deals mostly with electrons talking to electrons. Everything you can see, smell, touch, hear or taste is electrons talking to electrons. Gravity is what keeps your feet on the ground and the Earth moving around the Sun. Now you know how hard it is to fight gravity (just how many pull-ups can you do?) so it must be a strong force, right? Well it turns out that Gravity is the weakest of the 4 forces and it isn't just a little bit weaker. It is weaker than you can even imagine!

Sounds like we are right back to the start of this lesson again. Let's put some real numbers on this. The "weak" nuclear force is 10 to the 25th power stronger than Gravity. That's 100,000,000,000,000,000,000,000,000 times stronger! Electromagnetism - the force we know best - is 10 to the 36th power stronger than Gravity. That's 10,000,000,000,000,000,000,000,000,000,000,000,000 times stronger! The "strong" nuclear force is 10 to the 38th power stronger than Gravity. That's 1,000,000,000,000,000,000,000,000,000,000,000,000,000 times stronger!

Would you like a real, mind boggling picture for that? The diameter of the *smallest atom* , Hydrogen, is about 10 to the -10 power meters. The diameter of the *entire universe* is about 10 to the 26th power meters. So, the difference between the diameter of the smallest atom and the entire Universe is about 10 to the 36th power. Yup, that means that if you measured the gravitational attraction between the electron and proton in a Hydrogen atom it is about the same amount of force as the electromagnetic attraction of an electron and a proton at opposite sides of the Universe!!! If that doesn't boggle your mind, your mind is unboggleable! Gravity is *really* weak!

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