To get an idea of how empty deep space is on the average, perform the following calculations:  (a) Find the volume our Sun would occupy if it had an average density equal to the critical density of 10-26 kg / m3 thought necessary to halt the expansion of the universe.  (b) Find the radius of a sphere of this volume in light years. (c) What would this radius be if the density were that of luminous matter, which is approximately 5% that of the critical density?  (d) Compare the radius found in part (c) with the 4-ly average separation of stars in the arms of the Milky Way.

Q: If there is no observable edge to the universe, can we determine where its center of expansion is?…

A: Let’s explain by taking a simple example of a balloon analogy to explain the expansion of the…

Q: Distances to local galaxies are determined by measuring the brightness of stars, called Cepheid…

A: Absolute brightness is a constant and is 10 parsecs from Earth whereas measured brightness depends…

Q: Assume the average density of the Universe is equal to the critical density. (a) Prove that the age…

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Q: Consider a universe where Big Bang nucleosynthesis produced significantly more 4He than 1H. Estimate…

A: We have to Consider a universe where Big Bang nucleosynthesis produced significantly more 4He than…

Q: The CMB contains roughly 400 million photons per m³. The energy of each photon depends on its…

A: Write the expression for the Wien displacement law. Here, T is the temperature.

Q: The critical mass density needed to just halt the expansion of the universe is approximately 10-26…

A: Given critical mass density needed to halt the expansion of the universe is ρcrirical = 10-26 kg/m3

Q: Some of the familiar hydrogen lines appear in the spectrum of quasar 3C9, but they are shifted so…

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Q: 40 Because the apparent recessional speeds of galaxies and quasars at great distances are close to…

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Q: If a galaxy is 9.2 Mpc away from Earth and recedes at 475 km/s, what is H0 (in km/s/Mpc)?

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Q: Assuming that the Hubble constant is, in fact, constant over the age of the universe, what is the…

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Q: What started the clumping of matter in the early universe that eventually became the seeds of…

A: The force that is carried by the field of virtual astronomical particles in the quantum field is…

Q: The answer is already shown, I am just confused about the steps. On part a, how does the 3.1447 go…

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Q: Let's say that the number density of galaxies in the universe is, on average, 3 × 10–68 galaxies/m3.…

A: Given :number density of galaxies, n = 3 × 10–68 galaxies/m3            Observable distance by…

Q: In the extreme relativistic limit, the electron speed v=c should be used instead of v=p/me to find…

A: In this question we are given in the extreme relativistic limit, the electron speed v=c should be…

Q: The CMB contains roughly 400 million photons per m³. The energy of each photon depends on its…

A: The wavelength is 0.0011 m. The energy of a photon is 1.807×10-22 J.

Q: The CMB contains roughly 400 million photons per m³. The energy of each photon depends on its…

A: Mass = E/c2

Q: If the universe is infinite, does it have a center? Discuss.

A: The universe is infinite, and what is know about the universe is gathered by analysing the…

Q: If the average density of the Universe is small compared with the critical density, the expansion of…

A: According to Hubble’s law v = HR The expression for R  is R=vΔt Thus, v=HvΔtΔt=1H Here, ∆t is the…

Q: Assume the average density of the universe is 0.1 of the critical density needed for closure. What…

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Q: The rest wavelength of the Hα transition of atomic hydrogen is 656.3 nm (recall that 1 nm=10-9 m).…

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Q: Assume a power law for the scale factor a = Ctn, where C is a constant. (a) For what values of n are…

A: Given data: Scale factor is, a=Ctn. C is a constant.

Q: (a) Calculate the approximate age of the universe from the average value of the Hubble constant, H0…

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Q: If some unknown cause of red shift—such as light becoming “tired” from traveling long distances…

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Q: What speed should a galaxy move with respect to us so that the sodium line at 589.0 nm is observed…

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Q: Hubble's law can be stated in vector form as v = HR. Outside the local group of galaxies, all…

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Q: In the reading, you were told that there were roughly 10,000 galaxies in the image of the Hubble…

A: Given:  one image of hubble ultra deep field is roughly 10 square arcminutes.  Number of galaxies in…

Q: The mass density of our universe is measured to be about 10-29 kg/m3. If an arbitrary point is…

A: mass density of our universe is measured to be about 10-29 kg/m3. If an arbitrary point is chosen as…

Q: The density of the universe is   a. equal to the critical density if the universe is closed.   b.…

A: Critical density is the average density of matter required for the universe to just halt it's…

Q: What curvature will the universe have if the matter and energy density of the universe is equal to…

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Q: Can you answer all of them from this rpoblem?

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Special Relativity

The theory of special relativity discusses how space and time are related to objects traveling along a straight line at a constant speed. Simply stated, as an object reaches the speed of light, its mass becomes infinite and it is unable to move faster than light. This interstellar speed limit has been the topic of much debate in astronomy, and also in science fiction when people consider how to fly over large distances.