# Fermilab

## Inquiring Minds

General physics
From very cold to very hot – and everything in between

1. Negative pressure
Some cubic thermodynamical equations of state predict negative pressures, have negative pressures any physical meaning? Could they be related to negative mass?

2. Audio waves and radio waves
What is the wave called when you combine an audio wave with a radio wave?

3. Extremely Low Frequency system
In Michigan, there is an ELF (extremely low frequency) underground cable. My students asked what it does. Can you help?

4. Melting ice
How much energy does it take to melt ice? How much does it cost?

5. Kepler's law
I have heard there is a proof of Kepler's law that involves geometry only -- no calculus. Can you help me find it?

6. Perpetual motion of atoms
I just wish someone could explain it to me (talking vveerryyy ssllloooowwwlllyyly) so that I can have at least a clue why atoms appear to be little perpetual motion machines that are somehow unaffected by gravity, friction etc. and just keep on going and going (like that bunny).

7. Lightning as a power source
I want to know whether lightning could be an electricity power source, such as water electricity, nuclear electricity, etc.

8. The number of atoms in the World
My question is what is the number of atoms in the world and why don't scientist agree on one number for them.

9. Why is the sky blue?
"Why is the sky blue? Does it have to do with the Cerenkov effect?"

10. Thermic Energy
"Is thermal energy exactly an energy like electromagnetic and gravitational energy? Why is there no vector potential associated with thermal energy?"

11. Instant Cold Drink
"I remember reading about a new idea: opening a can of pop, it will instantly turn cold. I was wondering if you knew how they could do this."

12. The Future of Physics
"We are constantly preoccupied with the next steps in our sciences. I would be interested to know, in your opinion, what the next fifteen steps are likely to be in physics in the 21st Century."

13. Color of the sky
"I was wondering what creates the color the sky? I know that it looks blue, but what is it actually?"

14. Surprise in friction experiments
"My sister just finished her coursework on friction. They find from their experiments that-as predicted-friction increases as the 'roughness' of the material increases. After a certain point, however, it decreases. Any idea why?"

15. Absolute highest temperature?
"It seems as if the absolute highest temperature must occur when atoms are vibrating at the speed of light. Is this true, and if it is, whattemperature is this?"

"Can you help me on what measurement it is that I need to prove Kepler's second law."

17. Centripetal or Centrifugal Force?
"Is there such a thing as centrifugal force, or has it proven to be non-existent?"

18. What is a MeV in grams?
"What is a mega-electron-volts (MeV) in grams? Can you give me meaningful units for E =mc^2?"

19. Photons: real waves or probability concept?
"Does an unobserved, unmeasured photon exist as an electromagnetic wave or as a 'wavefunction', that is, a probability wave?"

20. Zero Point Energy
"I recently read an article that made reference to something called Zero Point Energy. It said that every point in space can never be void of all energy. Could you expand on what the Zero Point Energy theory is?"

21. Six physics questions
I have six questions:
1. How long is a particle accelarator.
2. Are there weapons 40 times stronger than the fatman and little boy atomic bombs used in World War 2.
3. What does E=mc^2 mean?.
4. Does electricity in general move at the speed of light?
5. How was fusion discovered? Is it true that the sun is a ball of hydrogen that is in a fusion chain reaction?
6. How can you become a scientific worker at fermilab?

22. Friction in a light bulb
"My wife and I are having a friendly dispute over the cost of operating electric light bulbs. Some folks insist that there is no friction involved in electricity. Wouldn't it be nice if it did? Anyway, who could explain the facts with this dilemma?"

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