[Alan McDougall (OP)]

Hi,

A question,

Assuming what we call space outside the event horizon of the universe is a black void extending infinitely outward everywhere in every direction forever.

And you or I found ourselves alone in the unimaginable empty nothingness, inside a hypothetical spaceship that could speed up to an infinite speed in a pico second or less

We then start up our space ship and race into the dark emptiness at infinite speed and then stop.

Would we find ourselves following the image of ourselves?

Would we find ourselves back where we started?


Have we moved?

Have we stopped?

Is motion relative and can only exist if there in another object to compare our position with? 

Alan

[yor_on]

Quite lovely question that one.
How do we prove movement?
It's by comparison with another reference (frame), right?
So do motion exist in that 'sphere' at all as there are no reference frame?

But hey, how about acceleration then?
Well, now it hinges on if your friend have any way to look out.
If he/she doesn't, how will he/she separate a 'gravity' of one .G from a constant acceleration of one .G?
But in this universe he/she wouldn't be helped by any windows, would he/she?

So this person would no matter:) what acceleration constant, jagged or whatever still not be helped by looking out.
And if we assume that this spaceship is a unknown quantity to him/her.
Wouldn't it then be rather logical of him/her to assume that it is a form of 'gravity' no matter how it would act.
What do I win
Or?

[Bikerman]

Well, this is the famous 'Mach' hypothesis.
Mach posited that without an external frame of reference then there is no motion (or no way to classify motion).
Newton's bucket was an attempt to clarify this. If you take a bucket of water in this scenario and you spin it, then does the water obey the normal rules of rotational dynamics (ie does the water climb the sides at the edges of the bucket or not?).
A similar example would be two weights connected by a string. If you set the weights spinning around each other then does the string become tight or does it not?
Mach said no. Einstein said (originally) no, but later changed that answer when he considered General Relativity in more detail....

[LeeE]

The term "event horizon of the universe" is unknown to me - what does it mean?  Did you mean to refer to the observable universe?  Another problem is that I can't relate to finding myself "alone in the unimaginable empty nothingness" because once I've imagined it it can't be unimaginable anymore.

Because the universe is empty there would be nothing to illuminate your spaceship, to produce an 'image' of it.  If you shone a light ahead of you it would be re-absorbed by the hull of your spaceship as you overtook it.

Whether you ended up back where you started would depend on where you steered.

If something could travel at infinite speed it could, like DNA's Infinite Improbability Drive, pass through every point in the universe simultaneously, and probably an infinite number of times too.  You say that the spaceship accelerates to infinite speed in a pico second, or less, but as long as it doesn't take infinite time it'll result in infinite acceleration, which will be a pretty positive indication that you've moved, seeing as there aren't any other masses in your universe to produce gravity.  The deceleration when you stop will similarly confirm that you've stopped.

[Mad Mark]

I think there is a property of matter yet to be discovered yet maybe never to be proven that prevents matter existing in the same location in space time.
It could exist in space but not time if you were not to move.So for you to exist from one moment to the next,even if your ship was the only thing in the universe it would create motion similar to a electron circling the nuclease of a atom but as you are the only thing in the universe you would move in ever increasing circles but never where you started.
Actualy circles is not quite what I was trying to describe because if you were the only object in the universe you would move away from your starting point but at any given point in time you would exist everywhere just not where you have been before.

[graham.d]

This is quite an old question as has been alluded to already. It would not be the visulisation of the surroundings that much to do with the behaviour of your spacecraft. If it were just this you could be anywhere and simply close your eyes for the same effect :-) However I am sure this was not what was intended to be meant but more that you were to imagine that you and your craft were, effectively, the whole of matter within a (maybe) flat universe. As Lee implies, this may not be a possible allowable configuration with any physical validity, anymore than trying imagine the sound of one hand clapping. Nonetheless I suppose we can theorise (guess?).

In Quantum Electrodynamics (QED) Feynman proposed that action at a distance (fields) could be the sum of all interactions between objects in the universe. To get around the limitations of the speed of light he proposed a (normal) retarded wave and an advanced wave (going backward in time). Summing the relative effects of all these interactions gives a concept of inertia being related to all the other mass in the universe and potentially giving justification to Mach's principle. He only did the calculations for very simplistic cases, with some success, but I think got bored with the immensity of the mathematical task in trying to do it realistically. He believed it should be done, so for aspiring young theoretical physicists there is an opportunity...

The result for the loan spacecraft would be that the laws of physics would have different constants from what we experience in our universe. I imagine that (if it was possible for us or some thinking entity) to exist, that objects would have much less mass (even objects within the spacecraft) or, if you like, inertia. But there would be some because we are not talking about a single solitary particle so all the particles would still be interacting with the others in the craft.

This kind of addresses another thread on the site about what is inertia. It is, according to this theory, related to all the other mass in the universe.

[Soul Surfer]

The original question in the title is an impossibility.  If there is only one object there is no object to throw out to accelerate or retard the object and no object to make the observations.  once you have any of these the question does not apply because movement can be measured relative to the stuff you have thrown away.

[yor_on]

Thinking again (well it do works at times:)
To me it seems that motion is a prerequisite for spacetime.

I can not see a 'frame' in my mind without it.
And as long as we introduce an 'observer' there will be reference frames to measure motion in.
I don't know of any observed 'system' (seen from the inside of it) that won't have some kind of internal 'reference frame'?

Or do you have a suggestion for how that frame should be constructed?
Something consisting of what?
Thought only?

And how c(w)ould one test for that?

do you agree?

[Alan McDougall (OP)]

LeeE

The term "event horizon of the universe" is unknown to me - what does it mean?  Did you mean to refer to the observable universe?  Another problem is that I can't relate to finding myself "alone in the unimaginable empty nothingness" because once I've imagined it it can't be unimaginable anymore.

I wrongly used the term event horizon, this term relates to black holes sorry.
I meant the edge of the universe assuming of course it has an edge.

It the big bang happened when it was supposed to have happened then this EDGE would be the distance the light from this primordial event has travelled from the birth of the universe to where it is now, some 14.5 billion light years.

My question was about the absolute black nothingness that might exist outside this EDGE extending outward forever and infinite in dimension

Would a single object move in this emptiness with no reference point whatsoever

Alan

[Soul Surfer]

You've got it fundamentally wrong where you say the "edge" of the universe must be the velocity of light times the length of time since the big bang. 

The big bang was NOT an explosion. This term was a derogatory name coined by the "opposition" Continuous Creation camp that stuck. The expansion is the expansion of space itself NOT the velocity of things thrown out from an explosion and as such does not actually involve things moving through space where the speed limit is the velocity of light. 

There is therefore no upper limit to the expansion speed of space and our universe could be many times larger than this.  If processes like inflation occurred it is probably very many orders of magnitude larger than the farthest distance we could ever see.

The actual velocities of all the galaxies THROUGH SPACE are probably similar to the relative velocities of local galaxies ie a few hundred miles per second or a fraction of a percent of the velocity of light.

[yor_on]

reading you soulsurfer I start to wonder about mass and expansion.
Let's say that this expansion have no roots in 'c'.
How far might it have gone?
As mass is something created in 'time' which is something following 'c', if you follow me thoughts here:)

So do we have a sphere of spacetime, 'wrinkled' to mass that now are ever expanding into 'virgin' territiories?

[DoctorBeaver]

Whether you ended up back where you started would depend on where you steered.

It also depends on the geometry of spacetime. If you keep going in a straight line in a closed universe, you would return to your point of origin. In an open universe, you would just continue on forever.

[Soul Surfer]

yor on  I am sorry but I do not understand what you are trying to say.

[LeeE]

Whether you ended up back where you started would depend on where you steered.

It also depends on the geometry of spacetime. If you keep going in a straight line in a closed universe, you would return to your point of origin. In an open universe, you would just continue on forever.

Just a nit-pick really, but that assumes that the closed universe is regular in shape and doesn't change size.

[Alan McDougall (OP)]

Soul Surfer,

There is therefore no upper limit to the expansion speed of space and our universe could be many times larger than this.  If processes like inflation occurred it is probably very many orders of magnitude larger than the farthest distance we could ever see.

I know space without mass or energy is mass less and it is this mass less infinite eternal space that might have existed before the creation event into which the universe evolved.

Or at the moment of creation ,if there were a creation, or big bang, that was not an explosion as you said, but it is the term nearly all physicists use.

Space having no mass therefore not under ant constraint could just have expanding into infinity at infinite speed.

[yor_on]

Well Soulsurfer:)
I was thinking of that BB and the 'instant expansion' of spacetime it created.
What stops it from still expanding?

Thinking about it again:) the question seems two folded here.

1. Either this expansion has an 'motion' over 'c', and may still be 'creating' the right 'properties' for our spacetime.
2. Or the 'expansion' propagated by means unknown to us, not involving the concept of 'motion' at all

In either case the 'possible' size of the universe might be limit less.
How w(c)ould we proof it not?
As gravity is curved around 'our spacetime'.
Those thirteen billions something light-years we can see.
How would one test for such a proposal?

That the 'edge' of spacetime is in fact 'outside' both spacetime, and gravity too, at least as I envision it:)
As gravity to me is an all encompassing 'dimension' or 'field' even if it has a propagation to it at ('c').
Sort of like time:)

----------
And if i traveled to the 'interface' between our space time and the 'edge' and turned on my flashlight pointing away from 'us'.
Would I then see a beam propagate in that 'nothing'.

[Alan McDougall (OP)]

Anyway,

In an totally infinite void of absolute black nothingness, you simple "can not move" and time would have no meaning.

Time and movement are linked

That is my answer for what it is worth

Alan

[Soul Surfer]

yor_on I still dont understand what you are trying to say. I understand that your preferred language may not be english but please try to explin your thinking simply without missing out any stages in your thinking.  Until I can clearly understand your questions I cannot determine if they are sensible answer them or show where you are wrong in your thinking.

There is one fundamental feature in all our current models of the universe and that is it is not possible to ever get to the edge of them because there is no edge to the universe.  it is like trying to travel to the edge of our world you would either travel for ever or cross your original path somewhere

[yor_on]

Just using it as a 'frame' of comparison to our spacetime, I think?

"That the 'edge' of spacetime is in fact 'outside' both spacetime, and gravity too, at least as I envision it:)
As gravity to me is an all encompassing 'dimension' or 'field' even if it has a propagation to it at ('c').
Sort of like time:)"

It just means what you say, that we don't know the 'outside' of our spacetime.
If there is any?

I don't really use 'edge' when trying to decide whatever enclosure spacetime may be.
But I do like the word 'interface'

---------

Sorry Soulsurfer, I missed that first question you wrote.

I was thinking (mass=space='c'='spacetime')
Which differs from before inflation, where the only mass was 'quantum sized'.
Therefore freed from the arrow of time (new 'hobbyhorse' of mine I'm testing:)
And therefore from 'c'.

We could see the 'inflation' as growing in a 'time' flowing any which way (arrow:)
Which would allow for an infinite inflation.
Until what we deem matter started to bind our time into a 'time-wise' arrow again.

The only question to my mind is where space gets created from 'matter'.
soup (QM)-Inflation -- Matter <--> SpaceTime (Arrow) ..

And if I will be seen as truly 'certified' after writing this:)

But on the other tentacle?
ah well

[yor_on]

Well, this is the famous 'Mach' hypothesis.
Mach posited that without an external frame of reference then there is no motion (or no way to classify motion).
Newton's bucket was an attempt to clarify this. If you take a bucket of water in this scenario and you spin it, then does the water obey the normal rules of rotational dynamics (ie does the water climb the sides at the edges of the bucket or not?).
A similar example would be two weights connected by a string. If you set the weights spinning around each other then does the string become tight or does it not?
Mach said no. Einstein said (originally) no, but later changed that answer when he considered General Relativity in more detail....

Bikerman, thinking of it again:)

That has nothing to do with 'gravity' as a phenomena.
It doesn't really matter if the 'gravity' will affect the bucket 'this or that way'.

When we say that we will notice a difference that is from a preconceived perspective in which we 'go out' from a rotational not accelerating object in space and compare the gravitational effects from that to the gravitational effects of an accelerating object.

So it doesn't really discuss the 'matter' in question, 'gravitation'.

Or should we split up 'gravitation' in uniformly accelerating 'gravitation'.
Unevenly accelerating 'Gravitation'.

Coasting 'gravitation'(that would be, only that 'gravitation' created inside that frame by 'particles' residing there).

Earth (matter) defined 'gravitation'.

Its strange, it's like you have two (three? more??) different types that give the same effect.
One is definitely connected to 'matter'

The other one will also give you a 'gravitational' effect.
But it's created by transferring (transforming) more and more energy from an accelerating object.
The third one is the same but then transferring 'energy' to a stationary object (relative us observing)
Like Lightarrows 'black paper'

But if we had a cube that we heated to the same energy amount as what a comparable object 'starts with', when accelerating it, the 'gravitational' effect of that cube would be of a greater magnitude for the accelerating case as compared to a 'stationary' object heated.