If there is no end to the space

[Iggy]

I was using lightspeed as a constant measure of distance and making the point that a speeding alien's frame of reference is not going to change the actual, objective distance between sun and earth...

 

Which is completely wrong.

 

We measure light's speed between here and the sun at 8 light-minutes per 8 minutes.

The alien measures light's speed between here and the sun (for example) at 3 light-minutes per 3 minutes.

 

With the assertions you are making there is no doubt that you have no idea what you are doing. Distance expressed in light units is not constant.

 

I see how my quote above confuses the issue. I just meant that we have a universal instument of distance measure in that lightspeed is constant, so, for instance we can say that the sun is just over eight light minutes away from earth

 

The opposite is true. A constant speed of light means that a universal spatial distance is impossible.

 

I'm sorry Owl, but what you are saying is completely wrong and shows a profound and basic misunderstanding of relativity. You can't philosophically interpret a theory that you don't have even a basic understanding of.

 

So now you throw another one at me:

"Here it is in a simplified form: someone is moving left of you at 540 million miles per hour and someone else is moving to your right at 540 million miles per hour. How fast is the second person moving away from the first person? How fast, in other words, would the first person measure or say that the second person is moving away from himself?

 

That was the same one as before. Conceptually, there is no difference.

 

Your view of reality involves notions that are not consistent with each other which makes it impossible for you to answer the question I've just asked.

(I said I would not play that anymore

 

As expected.

 

You answer my challenge

 

I already answered:

 

special relativity really doesn’t suggest subjective idealism.

 

 

(...)relativity offers an objective reality independent of the various differing perceptions of reality that come with different frames of reference. You ask if it denies a cosmos independent of observational frames of reference and the answer is that it establishes exactly the opposite. This is what Dr. Rocket has been talking about.

 

I don't expect you to agree or even understand, but I gave you an honest answer.

 

 

Even I can do elementary math, but of course this another SR trick question since nothing can travel faster that lightspeed, which is 671 million miles an hour. So if I add the 540 million mph of the guy going away to my left onto the 540 million mph of the guy going away to my right... I get a billion and 80million mph.... which somewhat exeeds the universal speed limit.... so.... what is your point given that I know what SR means?

 

My point should be obvious. A classical treatment gives an answer that your view of the world finds unacceptable. Some other understanding of reality is necessary in order to answer the question in a way that does not conflict with your beliefs about the speed of light.

 

I can work you through the necessary changes to your view of reality so that you might reconcile your treatment of space and time with your beliefs about the speed of light.

 

If you don't think that is necessary then tell me what method would solve the problem and give an answer less than the speed of light. You don't have to work out the math--just tell me what method would work.

[owl]

Me:

I was using lightspeed as a constant measure of distance and making the point that a speeding alien's frame of reference is not going to change the actual, objective distance between sun and earth...

 

You (Iggy)"Which is completely wrong."

 

I know you know this but we have a complete failure of communication here, so I am going to cite the well known facts about distance to the sun... which, to my point, does not change with changes in frame of reference, like that of the alien above.

From Answers.com:

"What is the distance from earth to the sun?

... Answer

The average distance between the sun and the earth is 149 million kilometers (93 million miles).

 

Because of earth's elliptical orbit around the sun, the distance changes over the course of a year (one complete orbit of the sun):

 

We are closest at perihelion, during winter in the Northern Hemisphere (around January 3rd) at the minimum distance of 147 million km (91 million miles).

 

We are farthest away at aphelion, during summer in the Northern Hemisphere (around July 4th) at the maximum distance of 152 million km (94.5 million miles).

 

Light from the sun takes roughly 8 minutes to reach the earth traveling, of course, at the speed of light. Therefore you can say the sun is 8 light minutes away from the earth, just as you can say a star is light years away.

 

The distance from the sun to the earth is one Astronomical Unit (AU).

An AU, as defined by the International Astronomical Union, is the mean distance between the sun and the earth. That mean (or average) distance is about 149 million km (93 million miles)."

 

The above is what I am calling the actual, objective distance to the sun, regardless of relativity.

Let's start at square one. Do You deny the above facts?

[IM Egdall]

The distance to the Sun you quote is for a particular frame of reference; one where the Sun and the Earth are at rest with respect to each other. But the Earth moves with respect to the Sun. Thus the numbers you quote are only an approximation, albeit an excellent one. (This is because the speed of the Earth with respect to the Sun is a small percentage of the speed of light)

 

In our universe where pretty much everything is moving with respect to everything else, there is no absolute distance (or absolute time).

 

 

 

 

[owl]

The distance to the Sun you quote is for a particular frame of reference; one where the Sun and the Earth are at rest with respect to each other. But the Earth moves with respect to the Sun. Thus the numbers you quote are only an approximation, albeit an excellent one. (This is because the speed of the Earth with respect to the Sun is a small percentage of the speed of light)

 

In our universe where pretty much everything is moving with respect to everything else, there is no absolute distance (or absolute time).

I "dare" to "think outside the frame" intrinsic to relativity theory. My sense is that the cosmos is an objective reality independent of our measurements from different frames of reference. The facts about sun-to-earth distance cited above remain facts in an objective sense which transcends the "thought experiments" so familiar (even dogmatic) to relativity theory.

No, "Virginia," aliens approaching our solar system, having a different frame of reference as they would, will not change the facts cited above.

(It's almost like a cult in denial of an objective cosmos, now that relativity's Frame of Reference doctrine dominates sceince. Philosopically, this is subjective idealism with FOR as the "subject" defining "reality."

Edited February 23, 2011 by owl

[DrRocket]

And will you now agree that earth stays a bit over eight lights minutes from the sun no matter what speeding travelers see from "far out" frames of reference?

 

no

 

And how about those rods? Do they "really" contract in length according to observational frame of reference?

 

yes

 

Ans: Of course not.

 

wrong

 

If "yes" then' date=' by the same principle, namely subjective idealism, your world will disappear every time you blink![/quote']

 

wrong again

 

"There is no position so ridiculous that it has not been held by some philosopher." Cicero

 

 

 

You get my point?

 

You reject special relativity and all of evidence that supports it ?

Edited February 23, 2011 by DrRocket

[IM Egdall]

I "dare" to "think outside the frame" intrinsic to relativity theory. My sense is that the cosmos is an objective reality independent of our measurements from different frames of reference. The facts about sun-to-earth distance cited above remain facts in an objective sense which transcends the "thought experiments" so familiar (even dogmatic) to relativity theory.

No, "Virginia," aliens approaching our solar system, having a different frame of reference as they would, will not change the facts cited above.

(It's almost like a cult in denial of an objective cosmos, now that relativity's Frame of Reference doctrine dominates sceince. Philosopically, this is subjective idealism with FOR as the "subject" defining "reality."

 

You can dare all you want. This is a science forum. What you are proposing has no known scientific basis in evidence; your views are purely philosophical.

[owl]

The distance to the Sun you quote is for a particular frame of reference; one where the Sun and the Earth are at rest with respect to each other. But the Earth moves with respect to the Sun. Thus the numbers you quote are only an approximation, albeit an excellent one. (This is because the speed of the Earth with respect to the Sun is a small percentage of the speed of light)

 

In our universe where pretty much everything is moving with respect to everything else, there is no absolute distance (or absolute time).

The fact sheet I quoted already took into account the variation in earth-sun distance due to the elliptical orbit. But at any given moment, the variation from the average (about 93 million miles) is known.

So, the answer is, "yes," you and Iggy do deny these facts and also insist that the length of rods actually varies with the perspective from which they are seen. Fine. This puts relativity squarely in the camp of subjective idealism, subscribing to the absurd implications of same: namely that there is no objective world/cosmos existing in an of itself, independent from observational frame of reference. And, technically, those who hold fast to that philosophy will say, "Yes, my world does cease to exist everytime I blink.... or the old classic, "When a tree falls in the forest it makes no sound unless it is heard." (Aside from whatever creatures might hear it, it obviosly creates sound waves in the air whether ot not percieved by any "creatures" including relativity theorists.

I think this will conclude my little exposition on the philosophical basis of relativity theory. I'm tired of hammering on it, and no one here cares about the possibility of a real cosmos independent of information about it carried by light and other lightspeed (electromagnetic) information carriers.

I still have have no problem with, generally speaking, "signal delay" variance for who sees what and when differently. But that certainly does not make earth and sun vary in actual distance between them, just because different FOR perspectives see it differently. Again all real varience there is due to the elliptical orbit. Subjective idealism, see.

Enough already.

[Iggy]

So, the answer is, "yes," you and Iggy do deny these facts

 

The answer is "those facts are correct and true in earth's reference frame".

 

and also insist that the length of rods actually varies with the perspective from which they are seen.

 

"Perspective" is inaccurate. Length varies with velocity.

 

This is a science forum. What you are proposing has no known scientific basis in evidence; your views are purely philosophical.

 

I agree, and would add that even as purely philosophical views, they cannot be correct. Owl's views are not consistent with themselves making their validity impossible.

 

Owl, it is really very simple. If your view of space and time are correct then you solved this problem correctly:

 

Even I can do elementary math, but of course this another SR trick question since nothing can travel faster that lightspeed, which is 671 million miles an hour. So if I add the 540 million mph of the guy going away to my left onto the 540 million mph of the guy going away to my right... I get a billion and 80million mph.... which somewhat exeeds the universal speed limit.... so.... what is your point given that I know what SR means?

 

But, the "correct" answer that you got conflicts with another view you have concerning the speed of light. The two views that you have are mutually exclusive. It is, therefore, impossible for your view of the world to be correct.

 

It's almost like a cult

 

Until you can explain reality in a coherent way, you don't get to criticize others for their successful explanation. Space-time is an objective reality independent of various perspectives and frames of reference. Your philosophical objection is therefore wrong. Your view of the world is also shown to be illogical and wrong. All you have is handwaving and I don't think the cult members are going to pay attention to that for long.

[owl]

Iggy:

"But, the "correct" answer that you got conflicts with another view you have concerning the speed of light. The two views that you have are mutually exclusive. It is, therefore, impossible for your view of the world to be correct."

 

Rather than your usual cryptic challenges assuming superior knowledge without explicit explanation in each of your "tests," please explain in whatever detail it takes exactly what you mean above, and I will give another try at both understanding what you mean and explaining what I mean.

Also, you said:

'The answer is "those facts are correct and true in earth's reference frame".

I will be extremely careful with this question. Do you believe, and does relativity assert, that earth and sun constantly move closer together and further apart (not counting the variation in distance due to the elliptical orbit) with all possible different frames of reference?

 

You say: ""Perspective" is inaccurate. Length varies with velocity."

 

Consider a virtual "rod," not physically mutable by compacting in extreme accelleration or even "spagettification" as it is sucked into a black hole. How could changes in velocity change its length. This is just a reality check, from my perspective, on what you (and relativity)mean by "length varies with velocity" if not simply the above extremes of compacting and stretching.

 

You say, "I agree, and would add that even as purely philosophical views, they cannot be correct. Owl's views are not consistent with themselves making their validity impossible."

 

How, exactly, do you see the philosophy of subjective idealism inherent relativity, which I have expounded in detail, as "incorrect" and internally inconsistent. An actual dialogue requires specifics, not just empty accusations without details, such as you have pontificated here in the name of the doctrine of relativity.

[Iggy]

Rather than your usual cryptic challenges assuming superior knowledge without explicit explanation in each of your "tests," please explain in whatever detail it takes exactly what you mean above, and I will give another try at both understanding what you mean and explaining what I mean.

 

Here is the problem: Someone moves to your left at 540 million mph and someone else moves to your right at 540 million mph. This means that each person (left and right) covers a distance of 540 million miles in one hour between you and them. If distance and time are absolute (if they are not relative) then either person will find the velocity of the other person by doubling 540 million mph.

 

That is how you solved the problem and it is the correct way to solve the problem if you believe length and duration do not depend on frame of reference. It is called Galilean velocity addition.

 

The problem is that the answer is 1.6 times the speed of light and you do not believe (correct me if I am wrong) that anything can move faster than the speed of light. Absolute space and time have therefore led you to a contradiction with your own beliefs.

 

Special relativity solves this problem, but I think you need to be able to see it as a problem before you start rejecting the solution. Everyone will tell you that constant length and constant time are inconsistent with a constant speed of light. The thought experiment I'm giving is one way to see that inconsistency. It really is a logical inconsistency. The discovery at the end of the 19th century that the speed of light is constant did not work with classical mechanics. A whole new system of mechanics had to be created. Your classical view of space and time are logically inconsistent with a constant speed of light.

 

Also, you said:

'The answer is "those facts are correct and true in earth's reference frame".

I will be extremely careful with this question. Do you believe, and does relativity assert, that earth and sun constantly move closer together and further apart (not counting the variation in distance due to the elliptical orbit) with all possible different frames of reference?

 

The distance between them is different in different frames of reference. The distance is relative to reference frame. Distance is a function of velocity. Length depends on velocity. There is a distance / velocity relationship. As velocity changes, distance changes. The answer to "what distance do I find between those things?" depends on "what is their velocity relative to me".

 

If you suddenly accelerated to 0.999 times the speed of light toward the sun then you would reach it in about 22.31 seconds. You would find the distance between the sun and earth to be about 22.29 light-seconds. The sun would be moving toward you at 22.29 light-seconds per 22.31 seconds or .999 light-seconds per second or .999 times the speed of light. Light would be moving away from you at 1 light-second per second.

 

The distance between the earth and sun is relative to their velocity. In earth's reference frame the distance between the earth and sun is 8.3 light-minutes. In a reference frame where the sun and earth are moving .999 times the speed of light parallel to that distance it is 22.29 light-seconds. The length, distance, or space between the two things depends on reference frame.

 

You say: ""Perspective" is inaccurate. Length varies with velocity."

 

Consider a virtual "rod," not physically mutable by compacting in extreme accelleration or even "spagettification" as it is sucked into a black hole. How could changes in velocity change its length.

 

Length is a geometric aspect of the rod. In space-time the rod is four dimensional. The length, width, and height of the rod are 3 dimensional aspects of the four dimensional rod.

 

You say, "I agree, and would add that even as purely philosophical views, they cannot be correct. Owl's views are not consistent with themselves making their validity impossible."

 

How, exactly, do you see the philosophy of subjective idealism inherent relativity, which I have expounded in detail, as "incorrect" and internally inconsistent.

 

Your view of the world is internally inconsistent because classical mechanics is inconsistent with an invariant speed of light. As a separate issue, your belief that relativity is a form of subjective idealism is a misunderstanding of relativity because you do not know how to describe the world in an invariant way using space-time. There is a way to explain the world that everyone can agree on and does not depend on reference frame. It is just different from the way you explain the world. It has the added advantage of giving the right answers where your explanation does not.

Edited February 24, 2011 by Iggy

[michel123456]

(...) There is a way to explain the world that everyone can agree on and does not depend on reference frame. (...)

 

That's the point. You should expand on that.

 

What is invariant version of the Earth-Sun distance on which everyone can agree?

[IM Egdall]

That's the point. You should expand on that.

 

What is invariant version of the Earth-Sun distance on which everyone can agree?

 

There is no invariant description of distance. There is no invariant description of time. All the evidence, experiments, tests, etc. confirm this. Whether we like it or not, this is how the universe works.

 

But there is a combination of space and time which is invariant! It's called the spacetime interval. Take two events; like a light flash here at a certain time and a light flash there at another time. The separation in space (distance) between the locations of the flashes is called the space interval. The separation in time between the two flashes is called the time interval. Both are affected by motion. So both are not invariant; they are relative. Different observers moving at different speeds with respect to each other all measure different values for the space interval and the time interval between these same two events.

 

Now bear with me; the spacetime interval, ds is defined as: ds^2 = c^2dt^2 - dx^2 (One space dimension for simplicity) Here dt is the time interval and dx is the space interval. This so-called spacetime interval is invariant. That is, it is unaffected by the uniform motion of the observer. It is absolute. (Alll this comes from the fact that the speed of light is invariant. )

 

So the spacetime interval does not depend on reference frame. Say the Sun emits a single photon at its surface at some time. This is event 1. Then the photon strikes the surface of the Earth at a later time. This is event 2. Observers in motion with respect to each other will all disagree on the space interval (distance) between the two events. This means they disagree on the distance from the Sun to the Earth! And they also disagree on the time interval between the two events. That is how long it took the photon to go from the Sun to the Earth. But when they put there individual measurements of the space interval and time interval into the formula above, they all get the same value for the spacetime interval between the two events.. So the spacetime interval is the same for all observers.

Edited February 24, 2011 by I ME

[Iggy]

Me too, I me.

 

What is invariant version of the Earth-Sun distance on which everyone can agree?

 

The invariant distance in space-time is between events. People intuitively want the invariant to be between x,y,z coordinates in space, but it is between x,y,z,t coordinates in space-time.

[michel123456]

I asked for a number. Units are yours.

[Iggy]

I asked for a number.

 

I'm not sure where you asked for a number.

 

Units are yours.

 

I'm not sure what you mean. Any units are fine.

 

The invariant distance between two events in flat space-time can be found like I ME said. Pick an inertial frame (any inertial frame) and measure the spatial distance between events (with a ruler) and the temporal distance (with a clock). Square both, subtract one from the other, then take the square root. That will give you a number that anyone, in any inertial reference frame, can agree on.

[michel123456]

(...)The invariant distance between two events in flat space-time can be found like I ME said. Pick an inertial frame (any inertial frame) and measure the spatial distance between events (with a ruler) and the temporal distance (with a clock). Square both, subtract one from the other, then take the square root. That will give you a number that anyone, in any inertial reference frame, can agree on.

(emphasis mine).

 

That number.

 

Owl gave his one which you denied. We are waiting for yours.

 

countdown 9.

Edited February 25, 2011 by michel123456

[Sisyphus]

(emphasis mine).

 

That number.

 

Owl gave his one which you denied. We are waiting for yours.

 

countdown 9.

 

If I may, Owl gave a spatial distance between the Earth and the Sun, two locations in space. The invariant spacetime interval that Iggy is talking about is between events, i.e. particular points in space and time. Since the Earth and the Sun are not events, the equivalent value that you are asking for does not exist. If you specify locations and times in a given reference frame, then you could get a value with this formula:

 

s^2 = -(ct)^2 + d^2, where t is the time elapsed between the events and d is the distance between where they happened. In a different reference frame, t and d will both be different, but s will be the same.

 

Please correct me if I've misunderstood the misunderstanding - I've just been skimming the last few dozen posts.

[michel123456]

If I may, Owl gave a spatial distance between the Earth and the Sun, two locations in space. The invariant spacetime interval that Iggy is talking about is between events, i.e. particular points in space and time. Since the Earth and the Sun are not events, the equivalent value that you are asking for does not exist. If you specify locations and times in a given reference frame, then you could get a value with this formula:

 

s^2 = -(ct)^2 + d^2, where t is the time elapsed between the events and d is the distance between where they happened. In a different reference frame, t and d will both be different, but s will be the same.

 

Please correct me if I've misunderstood the misunderstanding - I've just been skimming the last few dozen posts.

 

Other members here have argued that there is an invariant value on which all inertial frames will agree. I am waiting for this value.

 

The Earth & Sun are not events? O.K. Take any date you whish, any place you want.

Iggy is a great boy, he doesn't need your rescue.

 

8.

Edited February 25, 2011 by michel123456

[Sisyphus]

Other members here have argued that there is an invariant value on which all inertial frames will agree. I am waiting for this value.

 

8.

 

Yes, between events. The Earth and the Sun are not events. They are objects, moving relative to one another, with durations of billions of years.

[michel123456]

You are consuming Iggy's countdown.

 

7.

[Iggy]

Other members here have argued that there is an invariant value on which all inertial frames will agree. I am waiting for this value.

 

The Earth & Sun are not events? O.K. Take any date you whish, any place you want.

 

The space-time distance between an event on earth now and an event on the sun 8.3 minutes from now (as measured in our frame) is 0. Physically, when the interval equals zero this means that a ray of light can intersect both events. The distance between an event on earth now and an even on the sun 10 minutes from now (as measured in our frame) is roughly five and one half. Physically, this means that a clock moving inertially between events will measure 5.5 minutes between them.

 

countdown 9.

 

I'm curious what you're counting down to.

[michel123456]

Are you sure you don't want to edit your last post to avoid confusion distance/interval & from now/ago, also putting units in your answer?

 

6

[Iggy]

Are you sure you don't want to edit your last post to avoid confusion distance/interval & from now/ago, also putting units in your answer?

 

6

 

If you find any part confusing then feel free to express that confusion. The units for the interval are light minutes (a unit of distance).

 

On the topic of editing posts, I found it confusing that you answered Sisyphus' posts by editing your earlier post that he was responding to.

[michel123456]

If you find any part confusing then feel free to express that confusion. The units for the interval are light minutes (a unit of distance).

 

On the topic of editing posts, I found it confusing that you answered Sisyphus' posts by editing your earlier post that he was responding to.

 

Sorry, Sysiphus is quicker than me. I posted it, read it, and edited without noticing Sysiphus's who posted in the meanwhile.

 

in bold the points that need clarification, with numbers.

 

The space-time distance(1) between an event on earth now and an event on the sun 8.3 minutes from now(2) (as measured in our frame) is 0. Physically, when the interval(3) equals zero this means that a ray of light can intersect both events. The distance(4) between an event on earth now and an even on the sun 10 minutes from now(5) (as measured in our frame) is roughly five and one half(6). Physically, this means that a clock moving inertially between events will measure 5.5 minutes between them(7).

 

(1)distance or interval ?

(2)from now or ago (in the future or in the past?)

(3)interval or space-time interval?

(4)distance or space-time interval?

(5)from now or ago (in the future or in the past?)

(6)"five and one half" what? apples?

(7) a clock measures time, not spacetime interval. I don't expect an answer in units of time.

 

Countdown paused.

Edited February 25, 2011 by michel123456

[Iggy]

(1)distance or interval ?

 

It is sometimes called the "space-time interval" and sometimes "space-time distance". Notice, for example:

The important fact about the space-time distance, called the space-time interval, is that it is invariant

 

http://www.physics.fsu.edu/users/ProsperH/AST3033/relativity/Interval.htm

 

(2)from now or ago (in the future or in the past?)

 

An event that is 8.3 minutes from now is in the future.

 

 

(3)interval or space-time interval?

 

"interval" is short for "space time interval".

 

(4)distance or space-time interval?

 

The space-time interval is a distance in space time.

 

(5)from now or ago (in the future or in the past?)

 

An event that is some minutes from now is in the future.

 

(6)"five and one half" what? apples?

 

I answered this in my last post. Light-minutes, not apples.

 

(7) a clock measures time, not spacetime interval. I don't expect an answer in units of time.

 

The unification of space and time is exemplified by the common practice of selecting a metric (the measure that specifies the interval between two events in spacetime) such that all four dimensions are measured in terms of units of distance: representing an event as (x0,x1,x2,x3) = (ct,x,y,z) (in the Lorentz metric) or (x1,x2,x3,x4) = (x,y,z,ict) (in the original Minkowski metric)[k] where c is the speed of light. The metrical descriptions of Minkowski Space and spacelike, lightlike, and timelike intervals given below follow this convention, as do the conventional formulations of the Lorentz transformation.

 

http://en.wikipedia.org/wiki/Spacetime

 

The speed of light converts between units of time and units of distance.