Johnny5
Senior Members-
Posts
1611 -
Joined
-
Last visited
Content Type
Profiles
Forums
Events
Everything posted by Johnny5
-
Do you know any calculus at all?
-
Swansont, you have just demonstrated that you understand a very important logical principle. Can you explain that principle?
-
She used to beat me, you have it backwards.
-
What situation did I make, which was hypothetical? Actually, all I did was derive the length contraction formula and time dilation formula from one assumption, namely that the speed of light is the same in all inertial reference frames. I thought the derivation was rather thorough myself.
-
How does this show that the limit is negative infinity? I don't even see the infinity symbol. Regards PS: Nice work again by the way. I'm going to follow this argument eventually.
-
That is the fact which is setting everyone wild these days. Actually let me modify this somewhat. It's not space that is expanding, the matter is moving away from the center of mass of the universe at an accelerated rate, rather than a constant one. You say tomAto I say tomahto kind of thing.
-
What does this mean, that it cannot be answered from a physics standpoint? Do you mean that the statement is not empirically verifiable?
-
Just yes or no please. Depending on the answer, I may rapidly learn GR or not.
-
Where Does Space End? It Must End Somewhere!
Johnny5 replied to Edisonian's topic in Astronomy and Cosmology
-
I would like some help developing what I am going to call frame theorems. For right now, I am going to define frame as synonymous with a three dimensional rectangular coordinate system. It's just easier to say frame. Theorem 1: If F is an inertial reference frame, then any frame G whose coordinates are related to the coordinates of F by a simple rotation through an angle f is also an inertial frame. Has anyone seen this theorem before? PS: Here is my goal. I want the frame theorems to increase my ability to solve physics problems. Specifically problems dealing with rotation, and translation. In other words, the goal of the theorems isn't to be in vain, knowledge of the theorems should actually increase my spatio-temporal reasoning ability. In other words, the theorems are to have a practical purpose.
-
Where Does Space End? It Must End Somewhere!
Johnny5 replied to Edisonian's topic in Astronomy and Cosmology
What do you mean? -
Where Does Space End? It Must End Somewhere!
Johnny5 replied to Edisonian's topic in Astronomy and Cosmology
Yes. I worked on this problem several months ago, with some others. They were quite knowledgable about GR by the way. -
A thought has been coming to me lately. The title of this thread doesn't mean a frame in which the speed of light is c. It has to do more with the work of Mach. In an otherwise empty universe, how can you tell whether or not something is spinning? Also Newton's bucket has been on my mind. Also the principle of equivalence has been on my mind. But what has really been on my mind is Galileo's law of inertia, or if you prefer, Newton's first law of motion. Postulate 1: Somewhere in the universe is the center of mass of the universe. Ok so postulate one asserts the existence of a preferred location in space, a special place in the universe. Now, suppose you were located there, and you could watch the motion of all the suns, stars, galaxies, moons, planets everything. And you can turn your head so as to look in any direction. View the universe in frames of reference of this kind. What Kind? Ones in which the center of mass of the universe is permanently at rest. Now, there is still the possibility that some of you will choose reference frames which are spinning wildly. But in any of these kinds of frames, Galileo's law of inertia will be false. Which brings me to where I am. I am considering reference frames with origin at the center of the universe, and in which Galileo's law of inertia is true. Are these frames special, in the sense that Mach's problem is solved? That's my question. The inertial frames are going to be ones in which a free particle is at rest, or moving in a straight line in one of the frames. So if you have just an eight ball that exists if there is a particle on the surface which isn't subjected to any force then either it should be at rest or moving in a straight line. If the eight ball appears to be spinning, then Galileo's law is false, which implies that such a frame isn't inertial. So the point then is this... special frames (or preferred frames) are ones in which Galileo's law is true in. Somehow, Galileo's law of inertia unifies physics.
-
The question has nothing to do with star trek, its about physics. In fact, its about the principle of equivalence. I can rephrase the question... Suppose in the future mankind builds a spaceship which can do the following... It can be at rest in an inertial reference frame in space, with the occupants floating. Then they can be gently pressed to the floor, once the engines are on so that their weight is Mg, what it is here on earth. Now, let F denote the frame in which they were originally at rest in. Right now, their acceleration a in this frame is equal to 9.8 m/s^2 SO HERE IS THE QUESTION... Suppose that a second propulsion system is now turned on, and their acceleration jumps to 1000g in frame F, but they still feel a weight W of Mg. Would the existence of such a ship invalidate the general theory of relativity? Yes OR No? If I am not being clear enough, I can improve on that.
-
Name that experiment. (Just a play on name that tune). Which experiment are you referring to? Or which experiment would swansont refer to. Give me the best experiment.
-
Swansont I just had an idea. But first, please answer my question in the other thread enititled "Question about General Relativity Theory."
-
There was only ONE event in the light clock example, so I am not sure what you mean by saying 'events.' I am not saying that the light clock experiment can be used to invalidate SR, maybe it can I don't know, but what I am saying is this: The light clock example allows a derivation of both the following formulas, under the assumption that the speed of light is the same in both frames (of the example) 1. Lorentz contraction formula 2. Time dilation formula So by understanding this example, one is sure to know that the following statement is true: If the speed of light is the same in every inertial reference frame then LCF is true and TDF is true. As far as proving that simultaneity is absolute, you need a different argument for that.
-
Oh sorry. Umm i know what happened, though it will be hard to explain, but i know what happened. I am going to try to explain... There are a lot of different ways to use "if then" Take mathematical definitions for example. A if and only if B So when you are given a definition like this you know... If A then B AND if B then A Because definitions are stipulated to be true, you can play around with it as much as you want. HOWEVER When we really reason in real time, we use the IF to denote something which we don't know the truth value of. So i guess the lesson is this. When a reasoning agent is reasoning, the IF part will probably indicate uncertainty. But not always. I guess what I was doing, was attempting to give meaning to the phrase "simultaneity is absolute" It has the form of a statement, and it also has meaning. I wasn't hypothesizing that simultaneity is absolute. I've already concluded it is. So my reasoning phase is beyond that now. But you don't accept that it is. Regards
-
Where Does Space End? It Must End Somewhere!
Johnny5 replied to Edisonian's topic in Astronomy and Cosmology
The simplest way to conclude that time travel is impossible, is to use conservation of mass. If you vanished from now, and jumped to some moment in time far in the future, or far in the past, the total mass of the universe now would change, which is impossible. If you don't like the term 'mass' you can think in terms of conservation of matter at the fundamental level. If you vanished from now, and jumped far into the future, or far into the past, then the total number of indestructible particles now, would vary, which is impossible. Regards PS: If the total mass of the universe varied, then the center of mass of the universe would move. It cannot move. Or perhaps I should say... it cannot move in the preferred frame, and if the mass of the universe could change then the center of mass of the universe would move in the preferred frame. If I am not being clear it doesn't really matter, because time travel into the far past or far future leads to a multiplicity of contradictions. -
Where Does Space End? It Must End Somewhere!
Johnny5 replied to Edisonian's topic in Astronomy and Cosmology
There are no paradoxes in reality. It's the law of non contradiction. Not (X and not X), for any statement X. Whenever you encounter something called a paradox, there's always a way out, it's just difficult to see it. Like take the barber paradox for example. Suppose that there is a barber who shaves all those who don't shave themselves, and only those who don't shave themselves. Who shaves the barber? Let 'shave' be a binary relation on the set of those who can be shaved. Read X-S-Y as "X shaves Y" Denote the barber, by the letter B. Now, consider the meaning of the statement, "The barber shaves all those who don't shave themselves. That means this. Suppose that you are an individual who doesn't shave themself. Then the barber must shave you. So for any X, if not (X-S-X) then (B-S-X). Now consider the meaning of the statement, "The only people the barber shaves are people who don't shave themselves." Think about what that means. It means that if Y is a person who the barber shaves, then it absolutely must be the case that not (Y-S-Y). In other words: For any Y: If B-S-Y then not (Y-S-Y). So you are told this: There is at least one B, such that: For any X, if not (X-S-X) then (B-S-X) AND For any X: If B-S-X then not (X-S-X). Using first order logic, you can simplify the previous expression to the following one, which is logically equivalent (meaning the two expressions denote statements which have the same truth value) There is at least one B such that: For any X: if not (X-S-X) then (B-S-X) AND If B-S-X then not (X-S-X). Now you can simplify this expression a bit further as: There is at least one B such that: For any X: not (X-S-X) if and only if (B-S-X) Now you can use the existential and universal quantifiers of first order logic, to write the previous expression like this: $ B "X: not (X-S-X) if and only if (B-S-X). Open scope of your first assumption: Suppose that the barber can shave himself. (B-S-B) We were told that for any X the following is true: not (X-S-X) if and only if (B-S-X) So it would be true for the barber. Therefore, the following should be true: not (B-S-B) if and only if (B-S-B) Your assumption will now lead you to this: (B-S-B) AND not (B-S-B) So it is impossible that the barber can shave himself, and you know this for sure. Now suppose that the barber doesn't shave himself. You were told that the following is true: for any X the following is true: not (X-S-X) if and only if (B-S-X) So it is true for B, so that the following is true: not (B-S-B) if and only if (B-S-B) Now, using your assumption, you can reach the following statement: (B-S-B) AND not (B-S-B) Which cannot possibly be true. So you now know this for sure... Regardless of whether or not the barber shaves himself: The barber does and doesn't shave himself. But you have no assumptions left what do you do now? Actually, there is one remaining assumption, and it is this... "There is at least one barber B, such that... " Therefore, there is no such barber, and there is no paradox. Regards -