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Physics, Astronomy & Cosmology / Re: Why does acceleration become so difficult at high velocities?
« on: 29/04/2021 14:49:51 »What is it that it that resists acceleration at higher velocities. If in relativity you are only aware within a frame of reference, why is high velocity acceleration so difficult?In Relativity, nothing, as far as the accelerating frame is concerned, inhibits further acceleration. So, if you were accelerating at 1g. You would measure your velocity as changing by 9.8 m/s every sec.
But, this doesn't mean that if you, for example, started at rest with respect to the Earth, that after doing this for 1 year by your clock, you would measure yourself as moving at a bit over 1c relative to the Earth (it ends up being closer to 0.79c)
This is a result of how velocities add up in Relativity.
Imagine you in this accelerating ship, and after accelerating to 0.1c relative to Earth, you drop off a space buoy ( this buoy maintains the same velocity relative to the Earth you had when you released it). You continue to accelerate until you are moving 0.1 c relative to this buoy. This will take the same amount of time by your clock as it did to get to 0.1c relative to the Earth.
If you now measure your speed relative to the Earth, you will find that is not 0.1c+0.1c = 0.2c, but (0.1c+0.1c)(1+0.1c(0.1c)/c^2) = ~1.98c
If you now drop off another buoy, accelerate until you are moving at 0.1c relative to it, you will measure your velocity as being ~0.292c relative to the Earth.
Keep doing this and the consecutive velocities relative to earth will be: 0.381c, 0.463c, 0.538c, 0.605c, 0.665c...
Each time, the relative velocity to Earth increases by a smaller amount, even though, you noticed nothing changing about your acceleration.
It is not that "something resists your acceleration", it is that the very nature of time and space determine your measurements.
Relativity is a model for time and space and their measurement, It has nothing to do with outside influences inhibiting acceleration.
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