Unanswered Questions
131 questions with no upvoted or accepted answers
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To what extent does the increased average airmass the Sun's light passes through contribute to the seasons?
The traditional explanation for the cause of seasons I have heard is that because of the angle of the axis of the Earth with respect to the ecliptic, the angle at which light rays hit the Earth's ...
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What are radio frequencies sensitive to in galaxies?
Apart from 21cm line studies, radio emissions as well as signatures of different radio sources, do radio frequencies help in the identification of a particular physical structure or presence of some ...
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Potential energy in an expanding universe
A question you wonderful geniuses can hopefully answer. Imagine a piece of string drawn between two galaxies. Space between the galaxies is expanding. What force is being applied to the string? Where ...
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Deviations of conservation laws in the context of cosmological evolution?
If energy is "not conserved" in General Relativity (or at least, it is difficult to define it) in the context of an accelerating expanding spacetime (like it happens in our Universe), are ...
- 1,017
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Cosmic microwave background the same as the first visible light at 379,000 yrs after the Big Bang? How do these measure the age of the universe?
Was the CMB emitted at the same time as visible light at 379,000 yrs after the BB ? Was this a one time event ? If headed away from us, how does it measure the age of the universe?
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How can a busy high school student get into learning Astronomy?
I'm a high school student that has loved physics for quite some time, but have only started dabbling with the more complex things. I know a fair bit about quantum mechanics and such as I like it, but ...
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What is the main difference between cyclotron, synchrotron, and gyrosynchrotron radiation?
How are these various types of radiation generated? What is the main difference between them? Can someone suggest a book related to these radiations?
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Why are CMB peak heights sensitive to the physical densities
A very simple question: why should it be that the CMB power spectrum allows constraints to be placed on the combination of parameters
$$\omega_c = \Omega_c h^2$$
$$\omega_b = \Omega_b h^2$$
as opposed ...
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Gravity on Mercury's highest elevation?
This post answers what is Mars' gravity at its highest point (Olympus Mons) compared to the Earth's and Mars' standard, it's 0.3736 g (Mars standard is 0.3794 g). This also seems to be the lowest ...
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Superconducting space dust; what transient fields could induce persistent current loops?
Science Alert's Superconductivity Has Been Discovered in Meteorites For The First Time quotes from Superconductivity found in meteorites (Wampler et al. PNAS March 23, 2020)
The paper describes the ...
CommunityBot
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Information on Planetary nebula formed from the death of our star the 'Sun'!
I want to know the expansion rate, composition, mass and density of hydrogen present of a Planetary nebula similar to that which will be formed after the death of our star the sun.
Knowing these ...
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Combined mass of binary stars
This is Question 17 from USAAAO Practice Round 2015. The answer is D. It would be best if someone can detail out the workings.
In a nearby star system, two stars are seen to orbit each other every
...
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Can "rock stars" form from interstellar dust?
Imagine a large and massive dust cloud made of solid phase micrometeoroids, asteroids and larger planetoids, all material in it is in solid phase, and contains no hydrogen or other volatiles in gas ...
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Mass of the universe
How do we calculate the mass of the universe taking into consideration dark matter?
Mass of visible matter can be computed by stellar method, but how do we calculate mass of dark matter which we don'...
CommunityBot
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Total number density of galaxies and problematic expression in practise
This post comes from physics exchange forum, I have transfered it here, maybe I will be luckier since I have not received answers on the other forum.
Here is the issue :
I am asked to give the ...
CommunityBot
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