Infinte Regress Timeline...

[skepticalbip]

I've discussed this.

The single event, or two events, or a billion events, is/are seen differently because the viewing is done under different conditions.

Seeing the same thing differently is not the same as seeing two separate things.

Yeah. I just don't get how the pole entering the tunnel is the same event as it exiting the tunnel?

I'd think someone with an understanding of relativity would have criticized my claim about length contraction being related to the individual EM events within the pole. I'd think you would notice that time dilation is related to the events within the pole- if length contraction was related to events within the pole, the pole's diameter would also contract.

I'm certainly not an expert on relativity but I have enough study using it to have a little familiarity. I didn't want to break into this particular discussion because it looked like you were having fun with it. But since you were wondering, Lorentz contraction is actually a real physical effect because the fabric of spacetime actually does "shrink" in the direction of travel. In this case, the rod and runner would be the block of spacetime effected so the thickness of the runner would also "shrink". However the diameter of the rod and the runner's height would be the same because that dimension is perpendicular to the direction of travel, not in the same direction. Other than the "shrinking" of spacetime, there is also a slowing of time (time dilation) and an increase of mass. All real physical effects that we often have to take into account.

If you want a better explanation of Lorentz contraction, google would probably link you to some explanation written by someone who really does know what they are talking about, certainly more than I do.

 

[untermensche]

unter,

There is no preferred frame of reference. Reality is a local phenomenon. We agree on nearby events.

In every frame of reference light goes c. That is nature's way of telling reality how fast clocks tick. But clocks are made of matter. Matter fills apace with a gravity field. Gravity fields affect how fast clocks run.

The GPS clock works just fine. Keeps perfect time. In that frame of reference. It is when we compare the number of clicks we see from or vantage point, our frame of reference, the GPS clock is running wrong. If we took a clock up to it to see why the rate is wrong, it synchs in rhythm to the one we brought along.

Time is a local phenomenon, as changeable as weather.

I don't disagree.

What this means is what we call an objective observation is actually a subjective observation based on our arbitrary velocity through space.

But just because there is no preferred frame of reference does not mean there is no objective reality. Everybody is seeing the same reality, but with a difference in velocity that reality looks differently to different observers.

And this goes back to my initial point that brought us down this road of relativity.

There is also objective time, an objective now, even if observers can experience time differently.

 

[untermensche]

I've discussed this.

The single event, or two events, or a billion events, is/are seen differently because the viewing is done under different conditions.

Seeing the same thing differently is not the same as seeing two separate things.

Yeah. I just don't get how the pole entering the tunnel is the same event as it exiting the tunnel?

I'd think someone with an understanding of relativity would have criticized my claim about length contraction being related to the individual EM events within the pole. I'd think you would notice that time dilation is related to the events within the pole- if length contraction was related to events within the pole, the pole's diameter would also contract.

I said, consider the pole moving through the tunnel one event, or two, or a billion events. It doesn't matter.

The fact remains, seeing the same event differently is not the same thing as seeing two different events.

 

[Juma]

You are right about perspectives, but the thing is: time is just another dimension. So the order of events really do depend on your perspective: your frame of reference.

I would say that a significant difference in velocity changes your perspective of events so that the order of events looks different. Just as a change in your position can make the order of events look different.

So close but no cigar...

You should have written: " just as a change in your position can make the order in space look different."

 

[George S]

unter,

There is no preferred frame of reference. Reality is a local phenomenon. We agree on nearby events.

In every frame of reference light goes c. That is nature's way of telling reality how fast clocks tick. But clocks are made of matter. Matter fills apace with a gravity field. Gravity fields affect how fast clocks run.

The GPS clock works just fine. Keeps perfect time. In that frame of reference. It is when we compare the number of clicks we see from or vantage point, our frame of reference, the GPS clock is running wrong. If we took a clock up to it to see why the rate is wrong, it synchs in rhythm to the one we brought along.

Time is a local phenomenon, as changeable as weather.

I don't disagree.

What this means is what we call an objective observation is actually a subjective observation based on our arbitrary velocity through space.

But just because there is no preferred frame of reference does not mean there is no objective reality. Everybody is seeing the same reality, but with a difference in velocity that reality looks differently to different observers.

And this goes back to my initial point that brought us down this road of relativity.

There is also objective time, an objective now, even if observers can experience time differently.

What you are calling "objective" is a frame of reference. Apparently your preferred one. Stop that!

 

[George S]

I would say that a significant difference in velocity changes your perspective of events so that the order of events looks different. Just as a change in your position can make the order of events look different.

So close but no cigar...

You should have written: " just as a change in your position can make the order in space look different."

So close...
"Just as change in position makes space look different as you move, it makes time look different too."

The key is c. Space-time adjusts itself in shape so that light goes c locally. Everywhere at once at all times.

There is no global "reality," no preferred frame of reference. Reality is a local phenomenon. Our largest local reality is that of the fixed stars. In that context -- in that frame of subjective reference -- events on Earth are objective. A spinning gyroscope spins relative to this fixed-star frame of reference. Planets, suns, galaxies, all whirl relative to this one frame. These spins are an embodiment of energy: angular momentum. Earth spins slowly enough so we can pretend our labs are fixed frames of reference so special relativity applies.

The universe plays in the key of c.

 

[skepticalbip]

So close but no cigar...

You should have written: " just as a change in your position can make the order in space look different."

So close...
"Just as change in position makes space look different as you move, it makes time look different too."

The key is c. Space-time adjusts itself in shape so that light goes c locally. Everywhere at once at all times.

That is certainly the route that lead Einstein to his conclusions. He began by questioning the nature of light and why the speed is always constant regardless of the relative motions of the source and observer.

However, he would have come to the same conclusions if he had began by questioning the nature of time and why the rate of passage of time decreased at a predictable rate as relative velocity increased. But then we didn't know this at the time he began questioning.

The universe plays in the key of c.

I like that.

 

[ryan]

Yeah. I just don't get how the pole entering the tunnel is the same event as it exiting the tunnel?

I'd think someone with an understanding of relativity would have criticized my claim about length contraction being related to the individual EM events within the pole. I'd think you would notice that time dilation is related to the events within the pole- if length contraction was related to events within the pole, the pole's diameter would also contract.

I said, consider the pole moving through the tunnel one event, or two, or a billion events. It doesn't matter.

The fact remains, seeing the same event differently is not the same thing as seeing two different events.

I think the problem here is that length contraction seems quite meaningless and is not falsifiable on its own. And off the top of my head, I don't even think it can make a difference to either frame of reference, or else the universe would actually have to split in two and have two different realities.

But, where relativity actually does make a lasting difference is with time. For example, let's say we both have meter sticks, and you are at rest relative to me. Then you go in a spaceship and fly at relativistic speeds, enough to decrease the length of your meter stick by, say, half. As we all know, when you come back, your meter stick will be the same size as it was before you left. But, if we do the same thing with clocks, your clock will continue to show the effect from time dilation when you come back. So this does go beyond just seeing two different events; the events being the two clocks as well as you and all the matter that accelerated. In this case, time dilation actually caused a different event to take place in the universe than if time dilation didn't exist, and not just a visual difference.

When it comes to time, an observer can be affected by the effects of time dilation.

Also, if you can accept that the lengths really do contract, then how can there be a length contraction and no length contraction?

 

[skepticalbip]

I said, consider the pole moving through the tunnel one event, or two, or a billion events. It doesn't matter.

The fact remains, seeing the same event differently is not the same thing as seeing two different events.

I think the problem here is that length contraction seems quite meaningless and is not falsifiable on its own. And off the top of my head, I don't even think it can make a difference to either frame of reference, or else the universe would actually have to split in two and have two different realities.

But, where relativity actually does make a lasting difference is with time. For example, let's say we both have meter sticks, and you are at rest relative to me. Then you go in a spaceship and fly at relativistic speeds, enough to decrease the length of your meter stick by, say, half. As we all know, when you come back, your meter stick will be the same size as it was before you left. But, if we do the same thing with clocks, your clock will continue to show the effect from time dilation when you come back. So this does go beyond just seeing two different events; the events being the two clocks as well as you and all the matter that accelerated. In this case, time dilation actually caused a different event to take place in the universe than if time dilation didn't exist, and not just a visual difference.

When it comes to time, an observer can be affected by the time dilation.

Very good point.

Also, if you can accept that the lengths really do contract, then how can there be a length contraction and no length contraction?

I think that the difference you are seeing here is that a clock keeps a record of the time elapsed and shows that less time elapsed during the trip than elapsed at home base. If it only measured the length of seconds without counting the seconds, then there would be no record. The meter stick doesn't keep a record of what it measured during the trip.

 

[ryan]

I think that the difference you are seeing here is that a clock keeps a record of the time elapsed and shows that less time elapsed during the trip than elapsed at home base. If it only measured the length of seconds without counting the seconds, then there would be no record. The meter stick doesn't keep a record of what it measured during the trip.

Yeah I agree because the clocks become synchronized when together again.

 

[Juma]

I think the problem here is that length contraction seems quite meaningless and is not falsifiable on its own. And off the top of my head, I don't even think it can make a difference to either frame of reference, or else the universe would actually have to split in two and have two different realities.

And that because you havent bothered to actually lern what the special theory of relativity really is about.

The fact is the opposite: if the universe is to continue to be coherent then length conctraction must be.

 

[ryan]

I think the problem here is that length contraction seems quite meaningless and is not falsifiable on its own. And off the top of my head, I don't even think it can make a difference to either frame of reference, or else the universe would actually have to split in two and have two different realities.

And that because you havent bothered to actually lern what the special theory of relativity really is about.

The fact is the opposite: if the universe is to continue to be coherent then length conctraction must be.

I don't think you read the rest of my post.

I studied special and general relativity and did well when tested.

But I will admit that I am a little fuzzy on the implications of length contraction. Length contraction doesn't seem to have a causal connection with the "proper" length. If it did, then it would seem to have to split the universe into two realities; the ladder gets hit by the closing doors and it doesn't. Untermensche has a point about there being one practical reality when it comes to length contraction, but I would have to disagree on it being only a difference of perspective.

 

[skepticalbip]

And that because you havent bothered to actually lern what the special theory of relativity really is about.

The fact is the opposite: if the universe is to continue to be coherent then length conctraction must be.

I don't think you read the rest of my post.

I studied special and general relativity and did well when tested.

But I will admit that I am a little fuzzy on the implications of length contraction. Length contraction doesn't seem to have a causal connection with the "proper" length. If it did, then it would seem to have to split the universe into two realities; the ladder gets hit by the closing doors and it doesn't. Untermensche has a point about there being one practical reality when it comes to length contraction, but I would have to disagree on it being only a difference of perspective.

Any denial of length contraction, in itself, isn't really so much a problem except for the fact that you can't arbitrarily say that one of the conclusions of relativity is wrong without saying they all are. They are all interdependent and all are conclusions of the same model. It's kinda like saying that 2+2=4 unless we are talking about peas.

And we have enough hard data from tests to tell us that the model of relativity has to be a pretty good description of reality.

 

[untermensche]

I would say that a significant difference in velocity changes your perspective of events so that the order of events looks different. Just as a change in your position can make the order of events look different.

So close but no cigar...

You should have written: " just as a change in your position can make the order in space look different."

It's still only a change is appearance not a change in the order of time.

Time has only one order that can appear to change depending on your frame of reference.

Since nobody has a privileged frame of reference none can see the true order of time without periodic distortions. Like looking through water.

 

[untermensche]

I don't disagree.

What this means is what we call an objective observation is actually a subjective observation based on our arbitrary velocity through space.

But just because there is no preferred frame of reference does not mean there is no objective reality. Everybody is seeing the same reality, but with a difference in velocity that reality looks differently to different observers.

And this goes back to my initial point that brought us down this road of relativity.

There is also objective time, an objective now, even if observers can experience time differently.

What you are calling "objective" is a frame of reference. Apparently your preferred one. Stop that!

No, what I am calling objective is that which causes us to apprehend it.

No one has an objective view of it, but it is there. It is one thing, not infinite. Even if none of us can truly see what it looks like.

 

[untermensche]

Reality is a local phenomenon.

Reality is objective.

Our perception of reality is subjective.

 

[skepticalbip]

Reality is a local phenomenon.

Reality is objective.

And the objective reality of the universe is that spacetime is relative.

There is no Plato's cave.

 

[untermensche]

Reality is objective.

And the objective reality of the universe is that spacetime is relative.

There is no Plato's cave.

Spacetime is very objective.

Just because something changes does not mean it is not objective, as long as the changes occur objectively.

It is only human observation that is subjective.

 

[ryan]

Reality is a local phenomenon.

Reality is objective.

Our perception of reality is subjective.

At first I wasn't sure how to explain to you what I thought was wrong with an objective reality, but now I feel like I have some input.

Imagine you are floating in space. You look towards the Earth's surface with a telescope and see a millisecond clock ticking slower than your millisecond clock. An observer that can see your clock from Earth will see your clock running faster.

Objectively speaking, which clock has the correct time? Of course there is no answer.

 

[untermensche]

Imagine you are floating in space. You look towards the Earth's surface with a telescope and see a millisecond clock ticking slower than your millisecond clock. An observer that can see your clock from Earth will see your clock running faster.

Objectively speaking, which clock has the correct time? Of course there is no answer.

The perception of time for both is subjective.

The objective time is what they are both perceiving through their "lenses".

A reflection in a twisted mirror that creates a different distortion depending where you stand to look at it.

Each observer has a different picture but what is creating the picture is one thing.