Has the flat earth reached the speed of light yet?

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JJA

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Re: Has the flat earth reached the speed of light yet?
« Reply #30 on: November 19, 2020, 03:17:25 PM »
If you are in a car going 80mph and you press on the accelerator, do you feel 80mph of acceleration?  Of course not, that's absurd.
Talking about "80mph of acceleration" is absurd.

Exactly my point.  He said objects should fall at the speed of the world... I put that example into something easier to understand to show why it was wrong.

Re: Has the flat earth reached the speed of light yet?
« Reply #31 on: November 20, 2020, 06:35:39 AM »
Exactly my point.  He said objects should fall at the speed of the world... I put that example into something easier to understand to show why it was wrong.
Hey man, I'm generally on your side. I was just taking issue with your use of mph as a unit of acceleration.  It's a unit of velocity (which I'm sure you realize).

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JJA

  • 2673
  • Math is math!
Re: Has the flat earth reached the speed of light yet?
« Reply #32 on: November 20, 2020, 04:48:17 PM »
Exactly my point.  He said objects should fall at the speed of the world... I put that example into something easier to understand to show why it was wrong.
Hey man, I'm generally on your side. I was just taking issue with your use of mph as a unit of acceleration.  It's a unit of velocity (which I'm sure you realize).

I was using it wrong on purpose to make it easier to see what the original poster was doing wrong.  I should have been more sarcastic in my tone when using it.  Which is really surprising for me.  :)

Re: Has the flat earth reached the speed of light yet?
« Reply #33 on: November 21, 2020, 08:42:19 AM »
Feel free to dig around a little bit and see if you can come up with a real answer. I mean, you won't, because you can't, because there is no law that prevents something from being able to accelerate at a constant rate for an arbitrary amount of time. And that object will still never appear to exceed c to any observer.

How do we know this? because Einstein showed us. The same man who formulated the General Theory of Relativity, which describes how "gravity" works... the thing that keeps us fixed to the surface of the Earth.     
Odd. I'm pretty sure Einstein said Gravity doesn't exist.

I think what he meant by that was Gravity doesn't exist as a force, in the way that Newton described gravity.
Newton always thought that there was some kind of instantaneous force between two masses that pulled them together. Einstein realized this was wrong and that objects in freefall accelerating towards the Earth had no forces acting on them. It was this that led him to formulate his theory of general relativity (curved spacetime).

Just because in GR the proper acceleration at the Earth's surface is approx 9.81 m/s^2, doesn't mean its actually accelerating, for example in the UK the proper acceleration is 1g upwards and in Australia it has a proper acceleration of the same magnitude but in the opposite direction. So how can the Earth be accelerating in both directions?