Edwin Hubble observed that the light from very distant galaxies was redshifted and that the farther away a galaxy was, the greater its redshift. What does this say about very distant galaxies? When Hubble first estimated the Hubble constant, galaxy distances were still very uncertain, and he got a value for H of about 600 km/s per Mpc. What would this have implied about the age of the universe? What problems would this have presented for cosmologists?

Edwin Hubble observed that the light from very distant galaxies was redshifted and that the farther away a galaxy was, the greater its redshift. What does this say about very distant galaxies? When Hubble first estimated the Hubble constant, galaxy distances were still very uncertain, and he got a value for H of about 600 km/s per Mpc. What would this have implied about the age of the universe? What problems would this have presented for cosmologists?

College Physics

1st Edition

ISBN:9781938168000

Author:Paul Peter Urone, Roger Hinrichs

Publisher:Paul Peter Urone, Roger Hinrichs

Chapter34: Frontiers Of Physics

Section: Chapter Questions

Problem 3PE: (a) Estimate the mass of the luminous matter in the known universe, given there are 1011 galaxies,...

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(a) Estimate the mass of the luminous matter in the known universe, given there are 1011 galaxies, each containing 1011 stars of average mass 1.5 times that of our Sun. (b) How many protons (the most abundant nuclide) are there in this mates? (c) Estimate the total number of particles in the observable universe by multiplying the answer to (b) by two, since there is an electron for each proton, and then by 109, since there are far more particles (such as photons and neutrinos) in space than in luminous matter.
Suppose you are designing a proton decay experiment and you can detect 50 percent of the proton decays in a tank of water.If the actual lifetime is 1033 y , how long would you have to wait on an average to see a single proton decay?
More than 60 years ago, future Nobel laureate Sheldon Glashow predicted that if an antineutrino — the antimatter answer to the nearly massless neutrino — collided with an electron, it could produce a cascade of other particles. The Glashow resonance phenomenon is hard to detect, in large part because the antineutrino needs about 1,000 times more energy than what's produced in the most powerful colliders on Earth. Let's compare this event to an ordinary baseball with a mass of 146 g. Please use three significant figures in your calculations. 1.What is the threshold antineutrino energy for the Glashow resonance in peta electronvolts (PeV)? 2.What is this threshold energy in units of joules? 3.Now consider a baseball with the same kinetic energy as that of the Glashow resonance. What speed in m/s would correspond to this energy? 4.What is this rate in units of inches/second? please help!!
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More than 60 years ago, future Nobel laureate Sheldon Glashow predicted that if an antineutrino — the antimatter answer to the nearly massless neutrino — collided with an electron, it could produce a cascade of other particles. The Glashow resonance phenomenon is hard to detect, in large part because the antineutrino needs about 1,000 times more energy than what's produced in the most powerful colliders on Earth. 1. What is the threshold antineutrino energy for the Glashow resonance in peta electronvolts (PeV)? 2. What is this threshold energy in units of joules? 3.Now consider a baseball with the same kinetic energy as that of the Glashow resonance. What speed in m/s would correspond to this energy? 4.What is this rate in units of inches/second?
What mechanism can simultaneously solve both the flatness and horizon problems in cosmology?
The average particle energy needed to observe unification of forces is estimated to be 1019 GeV . (a) What is the rest mass in kilograms of a particle that has a rest mass of 1019 GeV/c2 ? (b) How many times the mass of a hydrogen atom is this?
(a) A particle and its antiparticle are at rest relative to an observer and annihilate (completely destroying both masses), creating two γ rays of equal energy. What is the characteristic γ -ray energy you would look for if searching for evidence of proton-antiproton annihilation? (The fact thatsuch radiation is rarely observed is evidence that there is very little antimatter in the universe.) (b) How does this compare with the 0.511-MeV energy associated with electron-positron annihilation?
Say that the mean lifetime of a π+ meson in its own rest frame is τ = 2.6 x 10-8 s. A pion of this lifetime is created at an altitude 100 km in the atmosphere by the collision of an incoming cosmic·ray proton with an atmospheric nucleus, and it has lifetime τ. Find the distance between the point of creatioin and the ground (in the pion's rest frame).
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