Guess scale factor of the, Ask an Expert

Academics

Question

Assume early universe was composed only of Helium instead of Hydrogen.

a) Estimate the temperature of CMB when Helium recombination occurred. Suppose that all the CMB photons have the average energy of the black body spectrum.

b) Repeat your approximation of the temperature, but now assume that you only need 1 photon per Helium atom to keep the atoms ionized. Also suppose fraction of photons with energy greater than E in a black body spectrum is approximately, exp (-E/kT)

c) guess scale factor of the Universe when Helium recombination occurred using your two different answers in part a and b.

View complete question

Physics, Academics

Category:- Physics
Reference No.:- M9134085

Have any Question?Write your Review or question?

Related Questions in Physics

What is the centripetal force which acts upon a 588 kg

What is the centripetal force which acts upon a 588 kg race car as it rounds a curve with a radius of curvature of 375 m at 60 m/s? please provide work to explain

Question a simple pendulum oscillates with frequency fa

Question: A simple pendulum oscillates with frequency f. (a) What is its frequency if the entire pendulum accelerates at 3/4g upward? (b) What is its frequency if accelerates at 0.75g downward? The response must be typed ...

Question three odd-shaped blocks of chocolate have the

Question: Three odd-shaped blocks of chocolate have the following masses and center-of-mass coordinates: (1) 0.300kg , (0.300 m, 0.300 m); (2) 0.400kg , (0.200 m, -0.400 m); (3) 0.200 kg , (-0.300m , 0.600 m). Find the x ...

A projectile is launched at an angle of 120deg above the

A projectile is launched at an angle of 12.0° above the horizontal. What is its initial speed if it hits a target that is located a horizontal distance of 175 m from the launch point and 11.0 m above the launch level?

Problem suppose a point charge produces a potential of -18

Problem: Suppose a point charge produces a potential of -1.8 V at a distance of 1.1 mm. What is the charge, in coulumbs, of the point charge? The response must be typed, single spaced, must be in times new roman font (si ...

Question part a at what angle icirccedil1 to the normal

Question: Part A: At what angle Î¸1 to the normal would the first dark ring be observed? Part B: Suppose that the light from the pinhole projects onto a screen 3 meters away. What is the radius of the first dark ring on ...

Question part a find the energy u0 stored in the capacitor

Question: Part A: Find the energy U0 stored in the capacitor. Express your answer in terms of A, d, V, and Ïµ0. Remember to enter Ïµ0 as epsilon_0. Part B: The capacitor is now disconnected from the battery, and the plat ...

A ball rolls off a table with a horizontal velocity of 5 ms

A ball rolls off a table with a horizontal velocity of 5 m/s if takes 0.6 seconds for it to reach the floor a) what's the vertical component of the ball's velocity just before it hits the floor b) what's the horizontal c ...

Question to take off from the ground an airplane must reach

Question: To take off from the ground, an airplane must reach a sufficiently high speed. The velocity required for the takeoff, the takeoff velocity, depends on several factors, including the weight of the aircraft and t ...

Questin a research submarine has a 30-cm-diameter window

Questin: A research submarine has a 30-cm-diameter window that is 9.0cm thick. The manufacturer says the window can withstand forces up to 1.2*10^6N . What is the submarine's maximum safe depth in salt water? The pressur ...

4,153,160 Questions Asked
13,132 Experts
2,558,936 Questions Answered

Ask Experts for help!!

Looking for Assignment Help?

Start excelling in your Courses, Get help with Assignment

Write us your full requirement for evaluation and you will receive response within 20 minutes turnaround time.

Ask Now Help with Problems, Get a Best Answer

Recent Questions

Ask Physics Expert