New answers tagged astrophysics
1
Here we go. Thanks gentlemen.
0
the calculations will look like a bunch of numbers and mathematical symbols, of course.
but seriously....
Astronomers use spectroscopic analysis of the light from the Sun, and from distant stars, to learn about them. Different elements and compunds emit different wavelengths of light, both visible and non visible to human eyes, when they are at different ...
1
It would make exactly as much difference as saying that a distance from Earth to Moon is 384399km or 238854 miles or 0.002569 astronomical units.
It's a matter to express quantities in whatever units are convenient to you. It doesn't make any difference to the physics and nature of things which units you choose. Choosing the 'right' units makes it only ...
2
Nothing substantive would change.
The units that we use in daily life (metres, kilograms, seconds, Watts etc) are based around everyday items. The kilogram is based on the mass of a certain amount of water. The Watt is based on the power required to push a mass with a force of 1N through 1m for 1s.
These units are great for most things, but they make ...
1
I think this alludes to the "solution" to the monopole problem given by cosmic inflation.
Grand Unified Theories predict the existence of magnetic monopoles: lots of them. So many that they would be easily observed. But we haven't observed a single one. Cosmic inflation solves this problem: the monopoles would be spread out by inflation, so there ...
6
Kepler knew the answer to this one:
The cannon ball follows an elliptic trajectory with the centre of mass of the Earth-cannonball system at the focus of the ellipse.
And Newton was able to do the maths to deduce this from an inverse square law central force.
A modern derivation can be found for example in this worksheet for Glasgow University
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As long as a neutron star emits any sort of elctromagnetic radiation, then it will emit radio waves, as the waves/particle gets 'redshifted' more and more.
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I think you answered your own question in the comments, but I'll answer here to provide a definitive answer.
the speaker says the sound horizon is about 500 thousand light-years.
You're missing out on the crucial part of that phrase which is "At the recombination, it was around five hundred thousand light years". That was more than 13 billions ...
9
To understand the history of the figure in question it is important to understand some of the context. In the run up to the operation of advanced LIGO, it was widely expected that the first detections would come in the form of relatively weak signals, whose presence in the data could only be established by comparing with theoretical templates through matched ...
4
This issue is a bit complex, and at its core revolves around the claim of a Copenhagen group led by Andrew Jackson that LIGO data was not handled correctly, a mislabeled plot, and some small (but since resolved) controversy regarding the transparency of LIGO science.
When LIGO published their initial findings, they included a plot that was, indeed, adjusted ...
5
Those are plots of the real spatial distribution of flux at certain frequencies, as it appears on the sky.
The latter can be seen as the x-y axis in each individual plot refer to the declination and rectascension ($\alpha-\delta$), i.e. standard celestrial coordinates.
The link provided in a comment has a plot of the spectrum of the two discs:
Such a 'total ...
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