If you observe light emitted from a distance object when the cosmic background temperature was Tz=54K, what is the redshift z of that light? At that redshift, what was the diameter Dz of the universe at that time compared to the diameter of today's universe D0?

Q: Estimate the age of the Universe, in years, using an outdated value of 99.90 km/s/Mpc for Hubble’s…

A: Outdated value is, 99.9 km/s/Mpc So, the age of universe is calculated as, Age= 1Outdated value

Q: Calculate the age of the universe if the Hubble constant were 65 km/s/Mpc.

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Q: I:28) What was the density of energy released of fusing 25% of all the hydrogen in the universe into…

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Q: Assume a flat FRW universe, dominated by radiation throughout its history. Calculate the physical,…

A: The objective of the question is to calculate the physical, cosmological horizon size at a given…

Q: Cite an evidence that we are living in an expanding universe.

A: The universe we are living in is expanding. This is evident from Hubble's observations in 1929. A…

Q: The temperature of the CMB today is T=2.725 K. Calculate the temperature of the CMB at redshift…

A: Given  T = To = 2.725 K z = 2000 Temperature of CMB at redshift  'z' is given by T = To (1+z)

Q: Assuming that hydrogen fusion requires the Universe to have a temperature of T ≥ 107 K (as measured…

A: The cosmic microwave background radiation (CMBR) is electromagnetic radiation, generated in the…

Q: How long will it take, in years, until today’s Hubble radius has expanded to 9 times its current…

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Q: What is the difference between hot dark matter and cold dark matter? What difference does that make…

A: Dark matter is a mysterious substance that makes up almost 85% of the universe's total mass.   It…

Q: Calculate the age of the universe if the Hubble's constant was 60 km-s¹ Mly¹.

A: Our universe is constantly expanding, It was observed by Edwin Hubble when he saw the galaxies…

Q: What are the possible fates for the universe? What do they depend on? What appears to be the actual…

A: In cosmology, the possible fates of the universe are broadly categorized into several scenarios…

Q: Calculate the critical density of a universe with Hubble constant of 89 km-s¹.Mpc¯¹.

A: It is observed that galaxies are moving away from each other and the farther they are faster they…

Q: If we find a galaxy that is moving away at 72,000 km/s, what does Hubble’s law tells us about the…

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Q: Suppose that we were to discover that all galaxies are actually twice as far away as we think. How…

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Q: In an empty Universe we can write PR = M = 0, 2x = 1. H² H² = (PRа+ + Ma³ + Q²₁a²²)→ H² = H₂₁²a-²…

A: Have a look dear

Q: b) The cosmic microwave background dates to a time when the universe was -380,000 years old, or to a…

A: Given: 380000 years ago Tr=3000 Kz=1100

Q: The mass of the neutrino plays an important role in the universe. Suppose the mass of two neutrinos…

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Q: The present number density of electrons in the Universe is the same as that of protons, about 0.2…

A: The present number density of electrons = 0.2m-3. Long before the formation of microwave background,…

Q: If the value of the Hubble's constant were found to be 60 km/s/Mpc, what would the Hubble time be?

A: The galaxies in our universe are moving away from each other. This was observed by Edwin Hubble. He…

Q: What does the size difference of the irregularities in the background radiation tell us about the…

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Q: 1. What is the total energy output of a radio galaxy in the local Universe (at z = 0.1) with a flux…

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Q: Calculate the Hubble time for a universe with a Hubble constant of sixty kilometers per second per…

A: Given:Hubble's constant, Ho = 60km/(s Mpc)Asked:Hubble's Time, tH = ?

Q: Use the Friedmann equations to show that the deceleration parameter go and the density parameter N…

A: According to Dark energy and the cosmological constant, the acceleration of the scale factor is…

Q: Assuming that hydrogen fusion requires the Universe to have a temperature of T > 10’ K (as measured…

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Q: Calculate the age of the universe for the following Hubble's constant, 200 1... - N (d) 20 km/s/Mpc

A: As per Hubble's law, the universe is expanding. If we assume that the expansion's apparent velocity…

Q: According to the version of the Big Bang Theory without a Cosmological Constant (and without Dark…

A: Hubble's Law states that as the universe is expanding in all directions, the receding velocity of an…

Q: What was the lowest temperature for photons to be able to produce 0 particles in the early universe?…

A: Given: kT=mc2

Q: Explain why it only appears that we are at the center of expansion of the universe and why an…

A: Universe is expanding from everywhere and it has no center of expansion. Materials expand from a…

Q: Why can't we see past the cosmological horizon? O The universe extends only to this horizon. O…

A: We can't see past the cosmological horizon because the only things that we saw on the night sky is…

Q: Assume a flat Friedmann-Robertson-Walker universe. Calculate the redshift z at which the temperature…

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

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Q: (a) What Hubble constant corresponds to an approximate age of the universe of 1010 y? To get an…

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Q: Using Ho = = 20.8 km/s/Mly and assuming the expansion rate has been constant, find out how long the…

A: It is observed that the galaxies in our universe are moving away from each other. This expansion of…

Q: a: Assume the universe is flat, and the density parameters of matter and the cosmological constant…

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Q: Calculate the critical density necessary for a closed universe for two extremes of the Hubble…

A: The critical density necessary for a closed universe for two extremes of the Hubble constant. given,…

Q: What would be the critical density of matter in the universe if the value of the Hubble constant…

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Q: Calculate the Hubble time for a universe with a Hubble constant of 60 km-s-1-Mpc-1.

A: Edwin Hubble observed that the galaxies were moving away from us. He calculated their recession…

Q: What evidence can you cite that the expansion of the universe is accelerating?

A: It is observed that galaxies are moving away from Earth at speeds proportional to their distance.…

Q: Explain how astronomers determined that the universe is expanding.

A: In universe there are millions of stars. These stars are always moving towards Earth or away from…

Q: TRUE OR FALSE: Current mass estimates and deceleration rates tell us that our universe is closed

A: The radiation filled Universe dilutes faster; it's density drops because the volume expands, while…

Q: What is meant by the critical density of the universe? Why is this quantity important to…

A: The critical density is the average density of matter necessary for the Universe's expansion to come…