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1. Are a composite particle composed of three quarks.
6. These are particles that make up all matter.
7. are unstable subtomic particles composed of one quark and one antiquark.
9. These are the particles that mediate the strong nuclear force.
11. Are particles that have the same mass as their ordinary matter equivalents but opposite properties like electromagnetic charge.
14. Suggests that matter was less permanent than originally thought.
15. Is the apparent movement of the closer stars relative to the background stars which is actually due to the motion of the earth.

2. Is the process in which matter is completely converted into energy.
3. Is the actual brightness of a star, regardless of the distance from the observer.
4. This theory was the main competitor to Hoyle's steady state theory.
5. Are six of the fundamental particles in the universe. They cannot be found individually and only exist bound by the strong force within hadrons.
8. Mechanics This suggests that matter was less permanent than originally thought.
10. Is the distance to a star that has a parallax angle of one arcsecond.
12. Are particles which mediate the various interactions between other particles.
13. Are a composite particle that contain quarks held together by a strong force.