Doer
Well-Known Member
A point in space is not an absolute reference. Absolute to itself? Meaningless.
The direction of the big bang
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mindphuk
Well-Known Member
Since the Home Depot is stationary relative to the road and you are specifying speed relative to the road and each other, it is simple to transfer the mechanics from one frame to the other. Your problem seems to be when speeds are given and the frame is assumed based on the wording of a problem, and not explicitly mentioned.
Let's say that Home Depot is decoupled from the earth, just like a source of light would be. Then the person traveling WITH the rotation of the earth will arrive at the HD earlier than the other person. Yet this is not what happens with light, even though it is decoupled from the earth's rotation and orbital speeds. Let's say this Home Depot blew up. We each will see the explosion at the same time. However, an observer from orbit will see the person traveling in the same direction as the rotation of the earth will see the explosion first.
Seedling
Well-Known Member
The 120 MPH is our relative speed. It is a closing speed between us. You have no idea of what component velocity each of us has relative to the road. You only know that the distance between us is decreasing at the rate of 120 MPH. That says NOTHING as to each of our speeds along the road.
mindphuk
Well-Known Member
Right. The road is in a different FoR than each of us. However, what does it matter what the speed relative to the road is unless we are measuring something on the road? If you move us into space, the closing distance is still 120mph and without a road for reference, there is no way to tell who is moving and how fast relative to a non-existent road. The only thing that matters now is that you are moving relative to me at 120mph and from your perspective I am moving toward you at 120mph. You can use the road to make another relative velocity measurement but it still is all relative and absolute velocities is meaningless, you need a reference point to make any velocity meaningful and by declaring a reference point, you are defining the FoR for what we are measuring.
How long are you going to ignore the fact that we have continually demonstrated that real-world experiments conflict with your hypothesis? Michelson and Morley were sure that light had to be tied to some absolute reference, that since it is a wave, it must propagate 'through' something. This is the same proposal you are making, that the light sphere has some absolute, fixed position from where it started so if we move away from that point, it should take longer for the light to reach us, i.e. your Z receiver in the box. However, their experiment, and every single one since then has shown that light does not propagate through anything and is not tied to any spacial coordinates. Experiments have proven that light behaves the same regardless of the frame's motion through space. This means that light speed is the same for all observers. Since your hypothesis contradicts this, then either the every experiment ever done is wrong or you are wrong. Since you haven't produced any experimental data that supports your belief, it can be dismissed as having been falsified. How can you keep disagreeing with this?
cannabineer
Ursus marijanus
Actually no. TNT was first described by German chemist Julius Wilbrand in 1863. cn
guy incognito
Well-Known Member
Alright, here is the kicker dude. Remember that example with lighting striking at the front of the train? The guy on the platform thinks the flash originated exactly M->A distance away from him when A and A' met up in his frame of reference. He saw the light come from there. From his perspective it happened at rest relative to him. From his perspective the flash happened M->A distance from him, therefore he calculates the time it took to get to him and all his measurements make sense to him. He comes to the conclusion that the strike happened in his frame of reference, and that he and the lighting strike were at rest and it was the train that was the one moving.
The lady in the train however disagrees. She saw the exact same lighting strike when A and A' aligned, however she sees it from the front of the train. She measured the distance from M'->A', and calculated the time it takes for light to get from the front of the train to her. From her perspective it happened at rest relative to her. From her perspective the flash happened M'->A' distance from her, therefore she calculates the time it took to get to her and all her measurements make sense to her. She comes to the conclusion that the strike happened in her frame of reference, and that she and the lighting strike were at rest and it was the platform/tracks/earth that was the one moving.
The light sphere originates exactly at the point A and A' align. The man sees A' (the point on the train) move away from the origin of the light sphere. He sees A and the center of the light sphere to be one and the same, and that never changes from his stationary perspective.
The woman agrees that the light sphere originates exactly when A and A' align. The difference however is that she sees A' and the center of the light sphere to be one and the same. She sees point A (the point on the platform) as moving away from the source of the light.
Now who is correct? A, A', and the lightning strike were all superimposed. There is no argument from anyone that that is the reality of how it happened. But what happens when A and A' move apart? Where does the origin of the light sphere go? The answer depends on who you ask. if you ask the man it stays at point A and does not move. If you ask the woman it stays at point A' and does not move. The answer is relative to who you ask.
guy incognito
Well-Known Member
Speed means absolutely nothing unless it's relative to something else. When you say the car is traveling 60mph you mean 60mph relative to the earth.
Lets say we are driving towards each other at 60mph each. All of a sudden the ground vanishes. It pops out of existence along with everything in the universe except for our 2 cars. Now your memory is wiped clear. You have no memory of the ground. You have absolutely no reference point to gauge your speed. You look around your car, and at yourself. You don't appear to be moving. You and the car and everything inside the car appears to be absolutely still. Now you see me coming at you in the opposite direction.
What speed do you determine me to be traveling?
What speed are you traveling? and how can you tell?
wrong again. From your perspective at the computer the light sphere originates in the center of the cube, then the cube moves away from it. From INSIDE the cube you do not see that. This is the exact same scenario from my previous post. From the computer you view the light sphere as eminating from the point A (just like your diagram shows). From INSIDE the sphere you see it as originating at A' (the center of the cube). No matter what perspective you have, the light sphere does not move relative to you.
guy incognito
Well-Known Member
Why? Any interaction between you 2 can then be calculated. In fact, the "absolute speed" you seem to speak of is the very definition of meaningless. What possible information can be gained from knowing your "absolute speed" in this scenario? If you want to transfer information, or objects, or avoid hitting the car the only thing that matters is your relative velocities. If you want to calculate a distance or a time for him to be at some coordinate on the ground, then you need to know his relative velocity in relation to the ground, which can be calculated from your relative velocity to the ground and his relative velocity to you. At no point, and for no reason, does knowing "absolute speed" provide any helpful information. If you measure the speed of light in your car, and he measures it in his car you both get c. Absolute speed does not exist, and cannot exist. The concept doesn't even make sense.
guy incognito
Well-Known Member
Yes. That is exactly what he (and I, and einstein, and M-M, and several others in this thread, and millions of scientist over the last hundred years) is saying. t=0 is by definition in the reference frame of you/earth/tree. If it was a meteor flying by just overhead it would be t'=0. t = t' only at 0. After that t' and t have different values. c remains constant for both. Therefore from each ones point of view they see a perfectly spherical light sphere emanate from the point of origin, and it stays in their FoR.
guy incognito
Well-Known Member
You need to know either your speed relative to the home depot, or his speed relative to home depot. This is not a result of using "relative" or "closing" speeds either. If you want to use your mythical "absolute" speed you still do not have sufficient information to solve the problem. You are implying that using relative speeds has a drawback because it is inherently lacking information. That is flawed and dishonest.
If you disagree please explain how would answer if you were given the "absolute" speed of both cars but not of the home depot.
cannabineer
Ursus marijanus
Second wind, Guy? cn
guy incognito
Well-Known Member
Yea. I'm pretty sure he is just trolling, but it still gives a good excuse to play out all these thought experiments to demonstrate how SR works. It is a tough concept. I spent many hours on the internet and on forums discussing it before I finally grasped it. I was never pig headed and stubborn like seedling is, but it was still difficult to grasp. When you have an intuitive belief so ingrained and someone comes along and turns you on your ear your natural response is to dismiss it as nonsense. But when EVERYONE is saying you are wrong, including the greatest minds of the last century, something else should click and make you say "wait a minute...why am I the only one not understanding this...". I suspect there are a lot of people on RIU that don't fully understand, but will be helped out enormously by all the examples and explanations in this thread.
cannabineer
Ursus marijanus
It is a tough concept, and I agree it's fun and worthwhile to be challenged about it. I've refined my own internal metaphors thanks to this thread and especially your contributions.
Here's a cool site that illustrates relativistic distortions. For some reason I have a tough time accessing the vid files; maybe you'll do better. cn
http://www.spacetimetravel.org/inhalt.html
Heisenberg
Well-Known Member
I enjoyed reading and thinking about your (plural) examples here. This was a new argument for me to witness, which is why I stayed out of it except for describing the smell of bullshit. I found it mostly stimulating, however, in the end all Seedling was able to demonstrate is that he is a denialist.
Seedling
Well-Known Member
Not even close. "Some men you just can't reach."
Seedling
Well-Known Member
Two cars are traveling towards each other on a road. One car has a speed of 30 MPH along the road, the other car has a speed of 70 MPH along the road. The distance between them is closing at the rate of 100 MPH. Each driver observes the distance between them as closing at that rate. According to SR, does each driver see the same number of meter sticks between them at every point in time? What I'm getting at is, if the distance between the cars in the road frame is 100 miles, and each driver sees that distance closing at the rate of 100 MPH, then all the frames (road, driver a, and driver b) see that distance as 100 miles, and they also see the time elapsing at the same rate, correct?
Another question:
At what rate does the center point of the cars change along the road as the distance between the cars decreases over time? For instance, there's a distance of 100 miles between the cars at t=0. Their center point is a Burger King that is 50 miles away from each of them. In one hour when the cars crash into each other, the car that was traveling 70 MPH is 20 miles past the Burger King, and the car that was traveling 30 MPH is 20 miles short of the Burger King. So the center point was the Burger King at t=0 seconds, and the final center point was 20 miles away from that point at t=3600 seconds. The center point changed at a rate of 20 MPH. Put that into your pipe and smoke it!!!!
...and yet another question:
Imagine the large spring spring as a light wave. The distance between the coils is the Wavelength. The NUMBER OF COILS is the cycles. The speed of light is equal to wavelength times frequency (cycles per second, or Hertz). In the pic assume the long spring to have completed 13 cycles, as the spring has roughly 13 complete coils over the total length of the spring.
As you compress the spring the wavelength gets shorter and the number of coils stays the same, correct?
Another question:
At what rate does the center point of the cars change along the road as the distance between the cars decreases over time? For instance, there's a distance of 100 miles between the cars at t=0. Their center point is a Burger King that is 50 miles away from each of them. In one hour when the cars crash into each other, the car that was traveling 70 MPH is 20 miles past the Burger King, and the car that was traveling 30 MPH is 20 miles short of the Burger King. So the center point was the Burger King at t=0 seconds, and the final center point was 20 miles away from that point at t=3600 seconds. The center point changed at a rate of 20 MPH. Put that into your pipe and smoke it!!!!
...and yet another question:
Imagine the large spring spring as a light wave. The distance between the coils is the Wavelength. The NUMBER OF COILS is the cycles. The speed of light is equal to wavelength times frequency (cycles per second, or Hertz). In the pic assume the long spring to have completed 13 cycles, as the spring has roughly 13 complete coils over the total length of the spring.
As you compress the spring the wavelength gets shorter and the number of coils stays the same, correct?
Heisenberg
Well-Known Member
Seedling says the darnedest things...
cannabineer
Ursus marijanus
Seedling, that's a useless question for two reasons:
1) The speeds involved are very slow and conform almost perfectly to the classical/Newtonian limit.
2) The presence of the road intuitively supports the spurious "preferred frame" that is the downfall of your entire hypothesis. You can get away with our intuition of Newtonian mechanics complete with Aristotelian aether at slowest speeds, but in a relativistic scheme that intuition harms more than helps. cn
1) The speeds involved are very slow and conform almost perfectly to the classical/Newtonian limit.
2) The presence of the road intuitively supports the spurious "preferred frame" that is the downfall of your entire hypothesis. You can get away with our intuition of Newtonian mechanics complete with Aristotelian aether at slowest speeds, but in a relativistic scheme that intuition harms more than helps. cn