Exam 41: Elementary Particles and the Beginning of the Universe

In the past neutrinos were thought to have zero mass.However,recent observations suggest that they have a small non-zero mass.One such observation is the electron neutrinos from the supernova 1987A which is 168,000 light-years from Earth.The neutrinos were observed within 13 seconds of each other.(Assume the supernova event occurred instantaneously.)This suggests that the difference in speed of the slowest neutrinos to the speed of light,c,is approximately

Redshift measurements of a galaxy yield a recession of 1700 km/s.Hubble's constant H is 23 km/s/10⁶ c·y.The distance to the galaxy is approximately

At the present time,the truly elementary particles are thought to be the

In the present understanding of the behavior of elementary particles,the term color is used to denote

The Starship Enterprise is powered by combining matter with antimatter.Suppose 1 kg of each are combined and ejected backwards at the speed of light,what is the final speed of the Enterprise starting from rest? Assume that the mass of the Enterprise is 10,000 kg and the spaceship does not reach relativistic speed.

Leptons

A possible explanation for the fact that an isolated quark has yet to be found is that

The charge of the u quark is

Hadrons are thought to be

Which of the following statements about particles and their interactions is true?

Particles that decay via the weak interaction have lifetimes of the order of

An electron with kinetic energy 589 keV collides with a positron of the same kinetic energy moving in the opposite direction.Calculate the wavelength of the two identical photons produced in the annihilation.

There is evidence that the universe is expanding like a loaf of raisin bread baking in an oven.This means that

Forces between electrons or positrons and nucleons that result in beta decay are best understood in terms of

The charge of the d quark is

A particle and its antiparticle must have

An antiproton is an atomic particle that has

A thousand years after the "Big Bang" the background temperature of the universe was at $\backsim$ 10⁵ K.The peak wavelength of the blackbody radiation at that temperature is

In the Standard Model,as with the leptons,there are 3 generations of quarks (u&d,c&s,and t&b).The reason for this is

Which of the following choices lists the four known types of forces in nature in order of decreasing strength?