Exam 41: Elementary Particles and the Beginning of the Universe

A classical calculation shows that the critical mass density of the universe is given by where H is the Hubble constant and G is the gravitation constant.If the density is below this value,the universe will expand forever whereas if it is above this value the universe will eventually stop expanding and collapses.Approximately,how many hydrogen atoms per m³ is the critical density equivalent to?

According to the standard model,

The fact that the reaction ³⁷Cl + $\bar{v}_{\mathrm{e}}$ $\to$ ³⁷Ar + e^- is not observed whereas the reaction p + $\bar{v}_{\mathrm{e}}$ $\to$ n + e⁺ is observed is understandable in terms of the conservation of

Which of the following statements about antiparticles is true?

What is baryon number,electric charge (in units of e),and strangeness for the three quark combination uuu?

The charge of the particle uss is

The cosmic background radiation is an important aspect of the Big Bang theory because it

What is baryon number,electric charge (in units of e),and strangeness for the three quark combination uds?