Assume the average density of the universe is 0.1 of the critical density needed for closure. What is the average number of protons per cubic meter, assuming the universe is composed mostly of hydrogen?

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: Estimate the age of the universe for a Hubble constant of (a)50km/s/Mpc, (b) 75km/s/Mpc, and (c) 100…

A: The Hubble time is t = 1/H0 . For each value of Ho, we have: a). t = 6.18 × 10¹⁷ s = 1.96 × 1010 yrs…

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: e gravitational energy of a pair of colliding galaxies , each of mass 10 Mo separated by a distance…

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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: What is the redshift z of a galaxy 193 Mpc away from us?   Note: Assume a value of the Hubble…

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Q: Current evidence suggests that the universe is   a. flat, infinite, and neither expanding nor…

A: To determine: The correct option.

Q: Is there any difference between antimatter, dark-matter, dark energy and degenerate matter?

A: Antimatter: It is like a simple matter. It also reflects the light. For example, positron is the…

Q: Because of the cosmological expansion, a particular emission from a distant galaxy has a wavelength…

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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: Suppose the Hubble constant were not 22 but 12.1 km/s per million light-years. Then what would the…

A: Write the expression for the volume of the sphere. Write the expression for the mass. Here, ρ is…

Q: why do you have to know the distance to a galaxy to find its mass?

A: The orbital motion of stars explains the masses of galaxies. The stars in a heavier galaxy exhibit…

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

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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: 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: Suppose the Hubble constant were not 22 but 53 km/s per million light-years. Then what would the…

A: Given: New Hubble constant, H' = 53 km/s per million light-years

Q: On average, how far away are galaxies that are moving away from us at 2.0% of the speed of light?

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Q: An electron jumps from n=3 to n=2 in a hydrogen atom in a distant galaxy, emitting light. If we…

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Q: Why aren’t the fluctuations there in the formation of Galaxies and other similar entities?

A: Galaxies and the other similar entities could not be without the existence of fluctuations in the…

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: The temperature of the universe is 2.76 K. What is the wavelength of the cosmic background…

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

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Q: How long ago was that galaxy right next door to our own Galaxy if it has always been receding at its…

A: The distance is 235 million light-years. The velocity is 4817.5 km/s.

Q: What is the estimated age of the Universe (in years) if the Hubble constant is 80 km/s/Mpc?

A: Hubble constant (H) = 80 kms-MpcUsing , 1 Pc = 3.08×1016 m= 80×1000 ms×106×3.08×1016 m = 2.59×10-18…

Q: Give examples of nonbaryonic matter.

A: nonbaryonic matter is the matter found in open space in dark matter. The major classification is…

Q: According to the standard Big Bang theory (neglecting any effects of cosmic acceleration), what is…

A: Hubble constant = 50 km/s/Mpc age of universe = inverse of hubble constant  = 1/(50 km/s/Mpc ) Using…

Q: Assume that a typical galaxy contains about 200 billion stars and that there are more than 150…

A: Given, a typical galaxy contains about 200 billion stars and that there are more than 150 billion…

Q: What is Hubble constant?

A: Introduction: Hubble constant is the constant of proportionality of the relative velocity of the…

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: Explain how and why Hubble’s observations showed that the universe is expanding?

A: According to Hubble's observation, the light from the galaxies farther away is shifted to longer…

Q: The Universe is approximately 13.8 Billion years old. What is the volume of the visible universe in…

A: Age of universe = 13.8 billion year Distance travel by light in 13.8 billion light year is.…

Q: What is the estimated age of the Universe (in years) if the Hubble constant is 60 km/s/Mpc?

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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.