jeffdanielk

I know a rank 3 tensor can be written as a 3D cube of numbers. But not every cube of numbers is a tensor.

Is there a way to multiply cubes of numbers together? An analog of matrix multiplication? 

A 3D torus is one example. It is made by mathematically gluing the top face of a cube to the bottom, the right face to the left, and the front face to the back, without any rotations. Some rotations will make other manifolds. 

A 3D surface of a hypersphere is NOT an example because the space is curved, not Euclidean.

The usual Euclidean 3D space is NOT an example, because it is infinite, not finite. 

The wind chill temperature is a function of two variables, temperature and wind speed. What is the formula? 

Travel Channel used to have shows about travel. They toured vacation spots and interesting places all over the world. What do ghosts have to do with travel? 

If we had tails, would pants have a hole in the rear for your tail to come out? Or would we curl it up inside our pants? Or put it down the pants leg?

Would your tail showing be considered obscene or rude?

Most big news stories are bad news:  Kennedy shot, Martin King shot, 9/11 terrorists, Pearl Harbor. 

What are a couple very big good news stories? 

Many World's Interpretation says that every time a particle interacts with a person, he goes into a superposition. So trillions of versions of every person exist in branches of his quantum wavefunction. 

Will all these versions of you meet the one God? Will they all then meet each other? Or is God in a superposition of states also? Or is there some other outcome? 

X = -2

X^2 = 4

✓(X^2) = ✓4

X = 2 

Therefore -2 = 2 

I know the square root of 4 is both 2 and -2, but the ✓ symbol is taken to mean only the positive root. 

Does it make sense to ask what direction an infinitely distant point is? 

Can one point be closer to (0,0) than another if they are both infinitely distant?If you have a right triangle whose legs are both infinite, how long is it's hypotenuse? Would it be an equilateral right triangle? 

Also, what is the worst record that theoretically could make the playoffs under the NFL playoffs format? 

In some states, people and businesses have filed law suits against the governor for his Corona restrictions. They claim they are unconstitutional. If the court rules them unconstitutional after the epidemic is over and those restrictions are already withdrawn, what happens? 

How can lost customers be given back to businesses? How can cancelled sports events be given back to fans? How can lost school days be given back to kids? How can cancelled carnivals/fairs/parades be given back to the people?

Could the field equations be expressed as partial differential equations only, without using tensor notation? Is tensor notation just a shorthand way of writing them? 

If a large ball of neutrinos was held together by its own gravity, would objects pass right thru it? Would objects in orbit around it appear to be orbiting nothing? Has anything like this been seen in astronomy? 

Water and salt are inorganic but we eat them. Are there any other substances without carbon in them that we could eat? 

Can the logical inference

If A = B, then B = A 

ever be false? Is there an algebra or type of logic or math entity in which this can be false? 

I understand that people could spread corona if they are gathered together physically. But why shouldn't people stay close with friends and family over Skype or email or Facebook or Twitter? Or telephone? Why shouldn't kids keep in touch with their friends with online video games? 

Corona virus can't be transmitted thru a computer. So why are we told to socal distance and not keep in touch with friends? 

I thought we always call the year BC. Where did BCE come from?