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aachenmann
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Can galaxies recede from us at velocities greater than c?
If yes, don't they violate the law of special relativity?
If yes, don't they violate the law of special relativity?
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Special relativity does not apply since such spacetimes are not flat. Also in flat spacetimes with a cosmological constant the equations from special relativity no longer apply.Mentz114 said:If you adopt a cosmoloy where distant things are receeding from any observer, but doing so in free-fall, the answers are 'yes' and 'no'.
Because of the 'yes', there will be an event horizon at a certain distance from the observer.
because the receeding matter in free-fall, thus not being accelerated, relativity is not compromised. There is a GR cosmological model which in fact predicts this.
aachenmann said:Can galaxies recede from us at velocities greater than c?
If yes, don't they violate the law of special relativity?
The concept of galaxies receding from us at velocities greater than the speed of light, or c, is based on the theory of general relativity. According to this theory, the fabric of space can expand faster than the speed of light, allowing galaxies to move away from each other at velocities greater than c. This expansion of space is not limited by the speed of light, as it is not an object moving through space, but rather the space itself expanding.
No, the expansion of space itself does not affect the movement of objects within a galaxy. The speed of light still remains the universal speed limit for objects moving through space. However, the expanding space can cause the distance between objects to increase at a rate faster than the speed of light, giving the illusion that the objects themselves are moving faster than c.
Currently, there is no evidence to suggest that galaxies are receding from us at velocities greater than c. In fact, due to the limitations of our technology and the vast distances of space, we can only observe galaxies receding from us at velocities within the range of c. However, it is possible that in the future, as our technology advances, we may be able to observe galaxies moving away from us at greater speeds.
Yes, according to observations and measurements, the expansion of space is accelerating. This means that galaxies are moving away from each other at faster and faster rates over time. This phenomenon is often referred to as "cosmic acceleration" and is believed to be caused by a mysterious force called dark energy.
No, the expansion of space will not cause galaxies to disappear from our view. While the distance between galaxies may continue to increase, they will still remain visible to us. However, due to the expansion of space, the light from these galaxies will be redshifted, making them appear to be moving away from us at very high velocities. This effect is known as cosmological redshift.