PV Gap

Vera Said:

1. One difference between the motion of electrons in an atom and the motion of planets in the solar systems is

We Answered:

is this suppose to be a quiz, cause the answers are b, none: it quarks, e , c

Louis Said:

Why does intergalactic space expand, but not not galaxies and solar systems themselves?

We Answered:

Gravity holds individual galaxies and solar systems together. The orbits of planets are continually adjusting for the expansion of space, just as stars in glaxies do, or in galaxy clusters. However, as some point, maybe about 100 million light years, the expansion of space becomes stronger than the gravitational attraction between galaxies and they fly apart.

Miriam Said:

Is it possible to derive nuclear fuel purely from solar energy?

We Answered:

Solar energy is the energy of light - photons of energy.
It is not a molecular or elemental substance.
Fusion is when multiple atoms of an element fuse into another element. Solar energy is not an element.

Nuclear fusion requires a lot of heat and pressure to fuse one element into another (such as hydrogen to helium in the sun).
Solar energy is not hot enough and does not create enough pressure to cause fusion (and you would still need the element to fuse).

But using the heat from solar energy to vaporize solid fuel in a spaceship would work (been done in other sci-fi stories, called a plasma drive in some stories).