Iggy

I agree. That's what I'm trying to explain. I'm using the Socratic method. The first claim I made is that your views contradict themselves. Demonstrating this may take more than a couple posts especially when you are throwing tangents everywhere. I asked two questions in my last post that were not ambiguous at all. If you will please indulge me with two very simple and direct answers.

The value of S in the diagram?

I had noticed. I didn't realize. I thought you were interested in numerical values.

Correct. Correct! Not exactly. Both t and x are, in a sense, variables. x is the spatial distance between events and t is the time between events (both expressed in the same frame of reference). I gave both x and t in my question. x is 5 light-minutes and t is 4 minutes. All we have to do is solve for s where I have given you x and t. S is the space time interval. No, here I think you had the problem. You cannot make x = 1 because x equaled 5 light-minutes in the question that I asked. You cannot simplify x=5 to x=1. No, you should get s2 = x2 - c2t2 where x=5, t=4, and c=1. With that you should be able to solve for s.

Correct, the interval is not one second, or a light-second. Measure the spatial distance between events in any frame. Call this [latex]\Delta X[/latex] Measure the time between events in that same frame. Call this [latex]\Delta \tau[/latex] Square (which means "multiply a number by itself") both numbers. Subtract one squared number by the other squared number (either from the other--it doesn't matter which) Whatever the answer is, take the square root of that answer. Whatever you get will be the spacetime interval between those two events. Does this help you with what I asked?

The quick answer is that it's arbitrary. It is a sign convention. Did you consider my question? Knowing how to calculate the interval it would significantly cut down the questions regarding what the value is... or should I start a countdown I explained very quickly how to find the interval in post 115 and I ME explained more in depth in #112.

Sure. In our reference frame (here on earth) the interval between an event on earth right now and another on the sun almost 8 days from now will be 200 billion kilometers. Blimey! I didn't realize. It must be very unconscious.

The statements contradict each other and you are not seeing why. Get two metal rods that are each 540 million miles long. Lay one to your left, pointing to your left, and another to your right, pointing right. Send someone down the length of each rod at 540 million mph. After one hour each person will be at the end of each rod. Yes? Everyone will agree on this, yes?

I honestly apologize if you are offended by the condescending and patronizing nature of my posts to you. I think you need someone to be brutally honest. Without even a basic cliff-notes understanding of relativity, the way you disparage the theory can't be well founded.

Yes, It was Let's do it again. In some random frame of reference the spatial distance between two events is 5 light-minutes and the time between them is 4 minutes. What is the distance between the events in spacetime that all frames of reference will agree on? Are you up for working through the answer? Did you read that section of the wikipedia page? http://en.wikipedia.org/wiki/Universe#Special_relativity_and_space-time

Yes, that was my exact answer in post #121.

Yes. If two events are separated by 149 million kilometers and 10 minutes in our reference frame then the space time interval will be 5.5 light-minutes or 98931511 kilometers. All other frames of reference will find the same interval for those two events. They will measure different values of space between the events and different values of time between the events, but all those other frames of reference will find the same value for the invariant space-time interval. The distance between those events in space time is invariant.

Thank you, Sisyphus. I don't believe you are dumb. There many conceivable events on the earth and sun. I gave two examples rather than one just to be thorough. I should also give a space-like interval... The space-time interval between an event on earth now and another on the sun 6.6 minutes from now (as measured in our frame) is roughly 5 and a half light-minutes. Physically, this means that a ruler stretched between the earth and sun will measure 5.5 light-minutes between events if that ruler is in a reference frame where the two events are simultaneous. I've given three examples. The space time interval in each case is the distance between events in spacetime that all frames of reference agree on. If you insist on having just one number then just pick any of the three examples. That is correct. Between the events in our frame of reference there are 10 minutes. In the frame of reference where a clock intersects both events (the clock moves between the earth and sun) it measures 5.5 minutes. It is roughly 5.5. I did it without a calculator. http://www.google.com/search?q=light+minute

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 An event that is 8.3 minutes from now is in the future. "interval" is short for "space time interval". The space-time interval is a distance in space time. An event that is some minutes from now is in the future. I answered this in my last post. Light-minutes, not apples. 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.

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.

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

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

Me too, I me. 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.

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. 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. 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. 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.

The answer is "those facts are correct and true in earth's reference frame". "Perspective" is inaccurate. Length varies with velocity. 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: 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. 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.

Yes, "stringently". Provisions are described here: http://labor-employment-law.lawyers.com/wage-and-hour-law/Child-Labor-under-the-Fair-Labor-Standards-Act.html Not really Yes, really. I gave you a specific example where congress passed a federal law involving the proscription of child labor which was upheld in the supreme court. I understand, but it is a mistaken opinion. You may want child labor to be a state's issue (which is fine--you are entitled to your opinion) but that is not the case.

Not exactly. The Fair Labor Standards Act (1938), a federal law, stringently regulates child labor. The history is kind of interesting. In 1918, in Hammer v. Dagenhardt, the supreme court ruled very much like you would want them to... that child labor is deplorable, but it is not the federal government's business to set laws regulating it. It is a state's right and responsibility. That decision was, however, overturned in 1941 with US vs. Darby. It asserts that the US government has the right to regulate the hiring and firing of workers because interstate commerce is in its preview. On these grounds federal laws restricting child labor (most especially the Fair Labor Standards Act, but also the Child Abuse Prevention and Treatment Act) have been and can be upheld. Therefore, the US congress has every legal right to affect laws involving child labor (as they have successfully done). No. I'm against forcing a person to work against their will. It really doesn't matter to me whether that person is a child or not. How come people act like things are only terrible when done to children? However, there is a difference--and I think you agreed with this in a later post though I think it bears repeating. Forcing a person to work against their will really isn't the issue. An 8-year-old will gladly agree to work if their parent asks them to whether or not it is in their interest to do so. This is why Jackson's comment misses the point, Jackson is mistaken for reasons that I'm about to quote, but more than that, that a child requests, or desires, employment matters not at all. The same right given to an adult has greater potential harm for a child. This is why, for example, a child saying "I want alcohol" isn't a reason to allow them to have it. I think this is what MoonTanMan was saying.

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. 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. That was the same one as before. Conceptually, there is no difference. (I said I would not play that anymore As expected. I already answered: I don't expect you to agree or even understand, but I gave you an honest answer. 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.

If the rest length (the length relative to the rest frame) is one meter then I don't agree that the rest length will be one inch.

I will not again go into SR with you. As expected. Until you try, there is no chance you will learn relativity. I didn't mention light or the speed of light in my latest question. I guess you didn't read it or consider it. 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? 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'm hoping that since you can't answer it you will realize there is a problem and ask, or at least try to figure out, what that problem is. I do not expect you to use relativity to answer the question I just asked. I expect you would use whatever understanding you have of reality to answer it. More than that, being able to use relativity does not mean a person has a philosophical understanding of it, but it is a prerequisite.