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Contrary to common misconception, it is equally valid to adopt a description in which space does not expand and objects simply move apart while under the influence of their mutual gravity. [ 2 ] [ 3 ] [ 4 ] Although cosmic expansion is often framed as a consequence of general relativity , it is also predicted by Newtonian gravity .
For supernovae at redshift less than around 0.1, or light travel time less than 10 percent of the age of the universe, this gives a nearly linear distance–redshift relation due to Hubble's law. At larger distances, since the expansion rate of the universe has changed over time, the distance-redshift relation deviates from linearity, and this ...
One classical thermal escape mechanism is Jeans escape, [1] named after British astronomer Sir James Jeans, who first described this process of atmospheric loss. [2] In a quantity of gas, the average velocity of any one molecule is measured by the gas's temperature, but the velocities of individual molecules change as they collide with one another, gaining and losing kinetic energy.
Another common source of confusion is that the accelerating universe does not imply that the Hubble parameter is actually increasing with time; since () ˙ / (), in most accelerating models increases relatively faster than ˙, so H decreases with time. (The recession velocity of one chosen galaxy does increase, but different galaxies passing a ...
The sound source is traveling at 1.4 times the speed of sound, c (Mach 1.4). Because the source is moving faster than the sound waves it creates, it actually leads the advancing wavefront. The sound source will pass by a stationary observer before the observer actually hears the sound it creates.
Formally, c is a conversion factor for changing the unit of time to the unit of space. [4] This makes it the only speed which does not depend either on the motion of an observer or a source of light and / or gravity. Thus, the speed of "light" is also the speed of gravitational waves, and further the speed of any massless particle.
Just because you were told one story growing up does not mean that was the most accurate retelling of events. It’s always a good idea to look back on the past and see it from multiple perspectives.
An illustrative example of the two effects is that sound travels only 4.3 times faster in water than air, despite enormous differences in compressibility of the two media. The reason is that the greater density of water, which works to slow sound in water relative to the air, nearly makes up for the compressibility differences in the two media.