User Kurt Hikes

1 vote

1 answer

119 views

Why is the FLRW universe (general relativity solution(s)) sometimes called the 'FRW universe'?

asked May 31, 2021 at 4:47

1 vote

2 answers

584 views

Why is a black hole's Hawking radiation temperature inversely proportional to its mass/size?

asked Nov 19, 2020 at 21:55

1 vote

1 answer

117 views

Shouldn't the estimate of the universe's age be higher, not lower, after the attractive strength of gravity is taken into account?

asked Mar 3, 2021 at 16:16

1 vote

0 answers

89 views

Objects beyond 13.3 billion light-years away are (apparently) moving away from us at faster-than-light speeds? [duplicate]

asked Mar 8, 2021 at 21:16

1 vote

0 answers

37 views

Does the Schwarzschild metric solution require two (A and B, or g11 and g44) or four components (g11, g22, g33 and g44)?

asked Dec 18, 2021 at 0:52

1 vote

1 answer

189 views

Do Einstein's ten field equations use 20 or 40 variables? (2 or 4 for each tensor equation?)

asked Dec 18, 2021 at 1:29

1 vote

0 answers

33 views

How can scientists deduce the number of types of neutrinos, or 'effective number', from Planck satellite data?

asked Nov 3, 2021 at 19:37

1 vote

0 answers

54 views

Why does Titan's (relatively) rapid migration away from Saturn cause the planet to wobble faster, and eventually (maybe) tip onto its side?

asked Oct 31, 2021 at 3:12

1 vote

1 answer

111 views

What exactly is the estimated distance to a far-off object when they say '50 Mpc/h' or '50 Mpc h^-1'? Is it less than 50 Mpc? Do you ÷ by 67 or 74?

asked Jan 28, 2022 at 19:09

1 vote

0 answers

46 views

What is the 'TE correlation' in the CMB, or 'temperature-E-mode' correlation, aka 'temperature-polarization' correlation?

asked Mar 26, 2022 at 13:15

1 vote

1 answer

486 views

What do 5-sigma, r, and lowercase-delta mean in the physical descriptions of major telescopes?

asked Sep 28, 2020 at 12:31

1 vote

1 answer

61 views

How is the H II 'region' directly detectable? By Compton or Thomson free-particle scattering? At what wavelengths?

asked Aug 3, 2021 at 19:10

1 vote

2 answers

179 views

What does an electron-capture supernova leave behind? A white dwarf, a neutron star or nothing?

asked Aug 4, 2021 at 22:40

1 vote

0 answers

58 views

Why does the 'Big Bang Nucleosynthesis' theory require that neutrinos, or at least sterile neutrinos, have a LARGE mass rather than a tiny one?

asked Aug 25, 2021 at 2:22

1 vote

1 answer

258 views

What direction does 0° in the J2000 epoch point towards on January 1, 2000?

asked Jun 18, 2020 at 23:11

0 votes

1 answer

77 views

What is the 'AT' astronomical catalogue? And the 'TXS' one? As in AT2019dsg and AT2019fdr?

asked Oct 17, 2021 at 5:48

0 votes

1 answer

54 views

Are plasma nuclei detectable? By the occasional emission of gamma rays, perhaps?

asked Aug 3, 2021 at 18:48

0 votes

1 answer

152 views

If the ratio of actual total mass to critical mass (Ω) in the universe is only about 0.3, why do cosmologists believe it is flat, as far as we see?

asked Nov 26, 2021 at 9:31

0 votes

1 answer

141 views

Why do planets' orbital velocities drop off by less than a third when twice as distant from the sun, rather than three-quarters? If gravity is $1/4$?

asked Nov 11, 2021 at 22:32

0 votes

1 answer

1k views

How do you calculate comoving distance and light's travel distance? According to the formulae below?

asked Feb 4, 2021 at 21:40

0 votes

1 answer

89 views

Are the most distant known objects in the universe more than 14 billion light years away? [duplicate]

asked Sep 28, 2020 at 20:48

0 votes

1 answer

210 views

Do free protons and neutrons absorb much radiation? To affect astronomers' observations? If so, at what wavelength(s)?

asked Jul 24, 2020 at 19:40

0 votes

0 answers

101 views

What was the energy/wavelength/frequency of the CMB when first emitted/released?

asked Aug 10, 2020 at 12:09

0 votes

1 answer

66 views

What is a dM1e red dwarf star? What do the '1' and 'e', specifically, stand for?

asked Mar 25, 2023 at 0:36

0 votes

2 answers

98 views

Does most of the Sun's energy and light come from its black-body temperature, due to its massive size alone? Constant crashing of particles?

asked Sep 18, 2023 at 16:05

0 votes

1 answer

242 views

Why don't scientists believe Earth's surface water came up from the mantle?

asked Sep 28, 2023 at 20:38

0 votes

1 answer

177 views

Why is the H-alpha line slightly shorter in wavelength (656.28 nm) in air than in vacuum (656.46 nm)? Shouldn't it be longer?

asked Nov 6, 2023 at 2:34

0 votes

0 answers

28 views

Is the hypothetical '(Don) Page curve' of evaporating black holes equal in time, so to speak, on both sides of the curve?

asked May 29 at 3:29

-2 votes

1 answer

913 views

What does 's' or 'ds' or $ds^2$ mean in the Schwarzschild equation(s)? [closed]

asked Nov 8, 2021 at 22:30

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119 Questions

Why is the FLRW universe (general relativity solution(s)) sometimes called the 'FRW universe'?

Why is a black hole's Hawking radiation temperature inversely proportional to its mass/size?

Shouldn't the estimate of the universe's age be higher, not lower, after the attractive strength of gravity is taken into account?

Objects beyond 13.3 billion light-years away are (apparently) moving away from us at faster-than-light speeds? [duplicate]

Does the Schwarzschild metric solution require two (A and B, or g11 and g44) or four components (g11, g22, g33 and g44)?

Do Einstein's ten field equations use 20 or 40 variables? (2 or 4 for each tensor equation?)

How can scientists deduce the number of types of neutrinos, or 'effective number', from Planck satellite data?

Why does Titan's (relatively) rapid migration away from Saturn cause the planet to wobble faster, and eventually (maybe) tip onto its side?

What exactly is the estimated distance to a far-off object when they say '50 Mpc/h' or '50 Mpc h^-1'? Is it less than 50 Mpc? Do you ÷ by 67 or 74?

What is the 'TE correlation' in the CMB, or 'temperature-E-mode' correlation, aka 'temperature-polarization' correlation?

What do 5-sigma, r, and lowercase-delta mean in the physical descriptions of major telescopes?

How is the H II 'region' directly detectable? By Compton or Thomson free-particle scattering? At what wavelengths?

What does an electron-capture supernova leave behind? A white dwarf, a neutron star or nothing?

Why does the 'Big Bang Nucleosynthesis' theory require that neutrinos, or at least sterile neutrinos, have a LARGE mass rather than a tiny one?

What direction does 0° in the J2000 epoch point towards on January 1, 2000?

What is the 'AT' astronomical catalogue? And the 'TXS' one? As in AT2019dsg and AT2019fdr?

Are plasma nuclei detectable? By the occasional emission of gamma rays, perhaps?

If the ratio of actual total mass to critical mass (Ω) in the universe is only about 0.3, why do cosmologists believe it is flat, as far as we see?

Why do planets' orbital velocities drop off by less than a third when twice as distant from the sun, rather than three-quarters? If gravity is $1/4$?

How do you calculate comoving distance and light's travel distance? According to the formulae below?

Are the most distant known objects in the universe more than 14 billion light years away? [duplicate]

Do free protons and neutrons absorb much radiation? To affect astronomers' observations? If so, at what wavelength(s)?

What was the energy/wavelength/frequency of the CMB when first emitted/released?

What is a dM1e red dwarf star? What do the '1' and 'e', specifically, stand for?

Does most of the Sun's energy and light come from its black-body temperature, due to its massive size alone? Constant crashing of particles?

Why don't scientists believe Earth's surface water came up from the mantle?

Why is the H-alpha line slightly shorter in wavelength (656.28 nm) in air than in vacuum (656.46 nm)? Shouldn't it be longer?

Is the hypothetical '(Don) Page curve' of evaporating black holes equal in time, so to speak, on both sides of the curve?

What does 's' or 'ds' or $ds^2$ mean in the Schwarzschild equation(s)? [closed]