[Epic Sauce]

If the Earth is constantly accelerating at 9.2 m/s, wouldn't we eventually reach the speed of light, and then beyond?
I'd like to know some thought about why the Earth is constantly accelerating, instead of going at a constant pace.

[Curious Squirrel]

If the Earth is constantly accelerating at 9.2 m/s, wouldn't we eventually reach the speed of light, and then beyond?
I'd like to know some thought about why the Earth is constantly accelerating, instead of going at a constant pace.

9.8 m/s/s*
It won't reach light speed due to things within the theory of Relativity.

In order for the idea to be a proper gravity analogue, it must be accelerating.

[GiantTurtle]

Yeah, relativity oversimplified is that your time slows down as you go faster, as each second is longer you don't have to accelerate as fast to increase your speed by 9.8m/s for each of your longer seconds. The faster you go the longer the same acceleration will take and you can never reach the speed of light just get infinitely closer.
The second question of why everything on earth is being fired at ever nearer to lightspeed through the universe is up for debate.

[3DGeek]

If the Earth is constantly accelerating at 9.2 m/s, wouldn't we eventually reach the speed of light, and then beyond?
I'd like to know some thought about why the Earth is constantly accelerating, instead of going at a constant pace.

It's called "relativity" for a reason.  All things only move in relation to other things.

So from the point of view of us here on earth, there is no contradiction.

Only from the point of view of an external observer would there be a problem.  But special relativity fixes that seeming inconsistency by stating that from the point of view of the external observer, time would start to run slower and slower here on Earth.  Hence we'd never reach lightspeed from the observer's perspective.

So there is no inconsistency here.

That doesn't make the Flat Earthers "right" - only "right about this".

[RoundEarthedFellow]

I'm terribly sorry, but Einstein's theory of General Relativity is entirely dependant upon gravity, and the time-stretch effect of fast-moving objects is dependant entirely upon the gravity of said objects- it's a multiplicative effect. Hence, Einstein's theory is only applicable to a round-earth, generally accepted model and is not compatible with anything to do with the Flat Earth theory or a model of the Universe in which gravity does not exist. A Flat Earther cannot use the theory of Relativity as a method of proving their theory of Universal Acceleration, that's preposterous.

[Mark_1984]

Yes, I’ve asked that before. Unsurprisingly, I didn’t get an answer.

You've missed my point.  Your Wiki quotes Einstein's theories of relativity and special relativity as the reason why the earth does not exceed the speed of light under the UA theory.  However, these theories are intertwined with Einstein's theories about gravity.  You can't have one without the other.  Therefore, either Einstein is correct, and gravity exists, or Einstein is wrong and there is no gravity, but then the speed of light is no longer a constant.  And we know from observations that the speed of light is a constant.

I'd be interested to hear a clear explanation.

More to the point, you Wiki quotes Einstein's theory of relativity as the explanation for why UA doesn't exceed the speed of light.  However, Einstein's theories explain gravity as a distortion space/time.  This only work with a spherical earth, and explains why the earth is spherical, why the atmosphere doesn't get sucked into space, why the water doesn't fall off the south pole, etc.  Why are you 'cherry picking' the parts of his theories that suit you, but are ignoring the parts you don't like.

Junker and I are referencing Einstein's Equivelence Principle.

[Rama Set]

I'm terribly sorry, but Einstein's theory of General Relativity is entirely dependant upon gravity, and the time-stretch effect of fast-moving objects is dependant entirely upon the gravity of said objects- it's a multiplicative effect. Hence, Einstein's theory is only applicable to a round-earth, generally accepted model and is not compatible with anything to do with the Flat Earth theory or a model of the Universe in which gravity does not exist. A Flat Earther cannot use the theory of Relativity as a method of proving their theory of Universal Acceleration, that's preposterous.

Time dilation, ruler contraction and relativistic mass change are not solely dependent on gravity. The Special Theory of Relativity showed that it is also an effect of approaching the speed of light.

[RoundEarthedFellow]

This is just plain wrong. I'm sorry but the time dilation effect is a multiplicative effect based on the gravity of the object. Put simply, and ignoring the constant of proportion, you could imagine the equation to be time dilation = speed X gravity (this is not the actual equation, don't nitpick). An object travelling at near light speed would have time dilation proportional to its gravity- an object of higher mass experiences more time dilation than that of a lower mass in accordance with the basic principles of gravitation. Without gravity, time dilation as explained in the theory of relativity does not and cannot exist, regardless of the speed of an object. To suggest that the Theory of Relativity could in any way benefit or support a Flat Earth model or disprove gravity is wholly preposterous.

[RoundEarthedFellow]

If you want it really spelled out, objects like black holes with incredibly high gravity experience time dilation even when moving slowly due to the multiplicative effect of their gravity. A smaller object like a planet has to move much closer to the speed of light to experience dilation, and an object with no gravity would never experience any. Gravity is a key part of the equation to find time dilation- at least according to Einstein's theories- and so to use those same theories to try to disprove gravity or support a model in which gravity doesn't exist DOES NOT HOLD WEIGHT.

[Mark_1984]

At the risk of making myself look dumb (considering the company, that’s a small risk LOL !) if we consider the earth to be made of massless particles, we would be travelling at the speed of light, coz that’s what photons do. Therefore at a constant velocity, therefore UA could not exist. (I think I’ve finally got down to their level of science, almost !)

[Rama Set]

If you want it really spelled out, objects like black holes with incredibly high gravity experience time dilation even when moving slowly due to the multiplicative effect of their gravity. A smaller object like a planet has to move much closer to the speed of light to experience dilation, and an object with no gravity would never experience any. Gravity is a key part of the equation to find time dilation- at least according to Einstein's theories- and so to use those same theories to try to disprove gravity or support a model in which gravity doesn't exist DOES NOT HOLD WEIGHT.

I know a decent amount about modern physics for a layperson and have never heard of “the gravity of an object”. Everything I have read indicates that time dilation occurs either due to a difference in relative velocity between two reference frames or because of a difference in gravitational potential between two reference frames or some combination thereof. If you wish to assert that velocity differences between reference frames are equivalent to gravitational potential it would be great if you could back it up.

[douglips]

If you want it really spelled out, objects like black holes with incredibly high gravity experience time dilation even when moving slowly due to the multiplicative effect of their gravity. A smaller object like a planet has to move much closer to the speed of light to experience dilation, and an object with no gravity would never experience any. Gravity is a key part of the equation to find time dilation- at least according to Einstein's theories- and so to use those same theories to try to disprove gravity or support a model in which gravity doesn't exist DOES NOT HOLD WEIGHT.

This is just wrong. The equation for time dilation does not include mass, only relative velocity.

T = T₀γ

γ is Gamma, not y (“why”).

γ = 1/sqrt( 1 - v²/c² )

No mass anywhere.

Even round earthers agree - uniform acceleration will never reach or exceed the speed of light.

[RoundEarthedFellow]

Actually, if you care to head on over to the Wikipedia page for time dilation- https://en.wikipedia.org/wiki/Time_dilation#Combined_effect_of_velocity_and_gravitational_time_dilation
You'll see that you are indeed correct- time dilation can be caused by both motion and mass- but the end result is a combined effect of the two- without one, the other cannot exist. It even gives the "combined effect" equation on the page, which interestingly is based off of the generally accepted model of our solar system and is incredibly accurate, which in itself gives fantastic evidence for a round-earth model. Of course Round Earthers would argue that uniform acceleration would never reach the speed of light- as long as gravity is accepted to exist, then this holds completely true as you will always be under the effect of gravitation from a celestial body of some kind, and gravity does indeed exist.
I'm not too sure where you got your equation from- it seems like it may be a simplified version of the equation to find the velocity constant in the equation, rather than the overall effect, though that's just my assumption through comparison with the wiki site- but it is indeed a combination effect.

[douglips]

Actually, if you care to head on over to the Wikipedia page for time dilation- https://en.wikipedia.org/wiki/Time_dilation#Combined_effect_of_velocity_and_gravitational_time_dilation
You'll see that you are indeed correct- time dilation can be caused by both motion and mass- but the end result is a combined effect of the two- without one, the other cannot exist.

Are you just trying to say that special relativity is a special case of general relativity? Because that's true.

So yes, a smaller object has to go faster relative to the observer to get the same time dilation, but in this case we're talking about some crazy pants universe where the Earth is accelerating at 1 g constantly so, mission accomplished?

[RoundEarthedFellow]

I think we're starting to see eye to eye. The problem is that in this "crazy-pants universe" gravity does not exist, and gravity is the driving force between the "smaller objects have to go faster" effect- which is on a spectrum all the way from no gravity = no dilation to infinite gravity = infinite dilation. This means that in a universe with no gravity, time dilation would never occur, and therefore uniform acceleration of the Earth would approach, and exceed, the speed of light with no questions asked. It can be going as fast as it wanted and time dilation would not take place because there would be no gravity to contribute to the combination effect.
This is why Einstein's principles cannot support a flat earth model or a universe in which gravity does not exist.

[3DGeek]

I think we're starting to see eye to eye. The problem is that in this "crazy-pants universe" gravity does not exist, and gravity is the driving force between the "smaller objects have to go faster" effect- which is on a spectrum all the way from no gravity = no dilation to infinite gravity = infinite dilation. This means that in a universe with no gravity, time dilation would never occur, and therefore uniform acceleration of the Earth would approach, and exceed, the speed of light with no questions asked. It can be going as fast as it wanted and time dilation would not take place because there would be no gravity to contribute to the combination effect.
This is why Einstein's principles cannot support a flat earth model or a universe in which gravity does not exist.

That's not true.  SPECIAL relativity applies without gravity.   GENERAL relativity says that uniform acceleration and a uniform gravitational field are equivalent.

Out in the universe, far, far from any stars or galaxies and where the gravitational forces have fallen below any conceivably measureable levels - the speed of light is still a constant - and THAT is the problem that requires special relativity to solve it.

But it doesn't prevent the Earth from accelerating upwards forever because time dilation would mean that we'd never reach lightspeed from an outsider's perspective.

[RoundEarthedFellow]

I can't pretend to be well-read on Special relativity so I'll take your word for it. I'd still appreciate some explanation for the endless, mysterious force causing this constant acceleration of the entire universe before I'm fully convinced though!

[gizmo910]

I can't pretend to be well-read on Special relativity so I'll take your word for it. I'd still appreciate some explanation for the endless, mysterious force causing this constant acceleration of the entire universe before I'm fully convinced though!

As would we all.
I'd also like to fully understand gravity, but it is likewise difficult to empirically deduce what exactly causes it.

Just assume that "dark energy" is what propels the flat disc, and space-time warping (and whatnot) causes gravity.

[Rama Set]

Just assume that "dark energy" is what propels the flat disc, and space-time warping (and whatnot) causes gravity.

Why should we assume that?

[gizmo910]

Just assume that "dark energy" is what propels the flat disc, and space-time warping (and whatnot) causes gravity.

Why should we assume that?

Assumptions remain until proven false.