If someone were to suggest that possibly half of the galaxies in the universe are composed of antiparticles ("anti-galaxies"), what argument(s) might you present to refute this hypothesis?

(Remember, atoms made of antiparticles have the same chemical and spectroscopic properties that our "ordinary" matter has.)


Astronomers see many galaxies colliding, and if a pair were composed of a galaxy and an antigalaxy, then ENORMOUS high energy radiation would escape (be seen) due to the particle-antiparticle annihilations.

Physics & Space Science

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Which of these is NOT a source of the shock waves that lead to protostars?

A) radiation from the OB stars in emission nebulae B) expanding Herbig-Haro objects C) expanding planetary nebula shells D) violent supernovae explosions E) collisions between galaxies

Physics & Space Science

At t = 0 the switch S is closed with the capacitor uncharged. If C = 30 ?F, ? = 50 V, and R = 10 k?, what is the potential difference across the capacitor when I = 2.0 mA?



a.
20 V

b.
15 V

c.
25 V

d.
30 V

e.
45 V

Physics & Space Science

Earth's core is mostly ___________ as indicated by the absence of S waves

a. solid b. liquid c. gas d. solid and gas e. solid, liquid, and gas

Physics & Space Science

In the equation A = B/C, the A and B are said to be _______________ proportional

a. directly b. inversely c. not d. exactly

Physics & Space Science