Einstein on Relativity

[webolife]

Just a few 2-bit insertions for consideration:
Relativity is about relationships.
Mass, space and time are all about relationships, this is how they are observed and measured.
Physics is all about relationships, this is the nature of reality.
Logic is all about making sense of relationships, "sense" being relative to the logician.
Expressing these relationships in the most elegant way possible is a [the?] goal of physics.
Any attempt to make physics about anything more "real" than these relationships is bound to be controversial, regardless of the intelligence of the teller. The observer begins with a set of premises about relationships, then logically wanders through the observations and verifies the measurements, and if the logic is impeccable, arrives at a conclusion that makes sense based upon the original premise... Or less often, changes the underlying premise. This [impeccably logical] conclusion will differ from the next logical observer's conclusion to the extent that there is a difference in original premises.
Where does this leave us? As Einstein also hoped, not with a capricious undetermined universe, but with whimsical science, controversies, debates... hopefully years of dialogue... a broader perspective, increasing tolerance, deeper understanding, maybe even some wisdom down the road.

Me on Relativity.

[Roshi]

Solutions of the Einstein field equations are spacetimes that result from solving the Einstein field equations (EFE) of general relativity

Can anyone explain why are there multiple solutions? Do they describe different Universes or "spacetimes" ?
https://en.wikipedia.org/wiki/Gravity#G ... relativity

Notable solutions of the Einstein field equations include:

The Schwarzschild solution, which describes spacetime surrounding a spherically symmetric non-rotating uncharged massive object. For compact enough objects, this solution generated a black hole with a central singularity. For radial distances from the center which are much greater than the Schwarzschild radius, the accelerations predicted by the Schwarzschild solution are practically identical to those predicted by Newton's theory of gravity.
The Reissner-Nordström solution, in which the central object has an electrical charge. For charges with a geometrized length which are less than the geometrized length of the mass of the object, this solution produces black holes with two event horizons.
The Kerr solution for rotating massive objects. This solution also produces black holes with multiple event horizons.
The Kerr-Newman solution for charged, rotating massive objects. This solution also produces black holes with multiple event horizons.
The cosmological Friedmann-Lemaître-Robertson-Walker solution, which predicts the expansion of the universe.

I'm curious what's with the "multiple solutions". Don't they exclude each other? What does a "solution" signify?

[Zyxzevn]

Solutions of the Einstein field equations are spacetimes that result from solving the Einstein field equations (EFE) of general relativity

Can anyone explain why are there multiple solutions? Do they describe different Universes or "spacetimes" ?
https://en.wikipedia.org/wiki/Gravity#G ... relativity

It is just mathematics.
You get a differential equation with multiple zeros or multiple singularities.
Like: 5 "merged" black holes rotating around each other, create 5 event horizons.

In mathematics it does not matter if it does not make any physical sense.

[Roshi]

In mathematics it does not matter if it does not make any physical sense.

True.

The "twin paradox":
https://en.wikipedia.org/wiki/Twin_para ... relativity

The paradoxical aspect of the twins' situation arises from the fact that at any given moment the travelling twin's clock is running slow in the earthbound twin's inertial frame, but equally the earthbound twin's clock is running slow in the travelling twin's inertial frame.[8][9][10] The resolution is that the earthbound twin is in the same inertial frame throughout the journey, but the travelling twin is not: in the simplest version of the thought-experiment the travelling twin switches at the midpoint of the trip from being at rest in an inertial frame with velocity in one direction (away from the earth) to being at rest in an inertial frame with velocity in the opposite direction (towards the earth).

Cool. What if we got 3 twins? Or 3 clocks. Two of them on distant spaceships that are stationary to each other (A, B) and one traveler C.

The traveler C goes from A to B and nothing happens, he does not remain younger, and his clock does not fall behind A and B, because what happens to him happens symmetrically to A and B. A and B have the same speed against C, and C has the same speed in relation to A or B. When he reaches B, C=A=B.

Then C does not change inertial frame and goes back to A so we can have magic stuff happening. B says "I will go", and goes to A. Again, nothing happens. Why would magic stuff happen only if C returns? When reaching B, C=A=B (also their clocks), it does not matter who returns. Does the Universe keep track of where he came from? Well - in that case who knows where B or A were before, and no speed or time can be measured ever again anywhere...

Is this explanation ok? I don't know what the mainstream is thinking when they accept "time dilation due to speed". They don't even know what it means. Time dilation due to gravity also does not exist, it's just the atomic clocks that are affected by gravity. I wrote more about "time" here.

[webolife]

Here's my ultra-simple 2-bits on the supposed paradox of twins:
Tie a string around the "full" end of an hourglass*-type 3-min eggtimer. Spin the hourglass speedily around for just a couple minutes... the timer will run out before the egg is done. This quite handily violates the paradox of the twins, but also simulates the forces involved in sending the twin out into space then later re-accelerating him back to earth. While gravitation is not the only unaccounted for force in the twins paradox, the closed curve trajectory inferred in the story must be a player in the resulting sense of time.

*The hourglass is an Einstein-certified clock that "should" obey the paradox.

[Roshi]

There is no "time" there are only clocks. Clocks are not driven forward by the "forces of time". Else they would just function without a battery. This includes atomic clocks. Whatever the cesium atom does, it does not do it because of "time making it do it". And atomic clocks are influenced by gravity and other forces, if they run slower in orbit - that's the reason.
This is another classic mistake of the mainstream - even if there could be other reasons for an atomic clock to run slower - we pick the one our religion tells us to pick. Same thing with redshift, same thing with the Higgs boson:

http://www.techtimes.com/articles/19802 ... er-all.htm

The Higgs could explain data obtained by CERN scientists using the Large Hadron Collider, but other particles could have created the data, suggesting there might be alternate explanations for it, they say in a paper published in the journal Physical Review D.

"The current data is not precise enough to determine exactly what the particle is," says university researcher Mads Toudal Frandsen. "It could be a number of other known particles."

Where are those "forces of time" inside the atom? What happens if the "forces of time" inside the cesium atom change intensity "in time"? Do we need to measure them with another clock?

Relativists just need a clock made by the gods, that's immune to anything, and runs forever at the same rate just because "time" makes it run. Problem - according to relativity, it's enough to move the clock, and it will speed up or slow down. Don't even need to move it, just calculate it's speed against a bus in Hong Kong, or against a bird in the park. And it will run at different rates at the same time, because of different speeds. No physical explanation given, about why "the forces of time" change as we measure our clock's speed, it's just a coordinate transformation that does it... Even more amazing, the clock changes rate, as soon as we do a calculation of it's speed (it has millions of speeds against millions of objects) and write it on paper. It would be cool in a Harry Potter movie...

https://en.wikipedia.org/wiki/Time_dila ... e_velocity

[Lloyd]

TWIN PARADOX
Here's Nevyn's explanation that there is no actual paradox, but just a peculiarity involved in measuring time or distance with photons that have limited velocity (from http://forums.naturalphilosophy.org/sho ... php?tid=69).

The Twins Paradox is not a paradox and is not even a problem once you treat Relativity in a mechanical manner. Relativity is a theory of measurement, not existence. Therefore, it only applies to measurements and not time or distance itself. That is why you have to pick a single reference frame and are not allowed to change that (which the Wiki argument does). The reference frame is the point that measurements are made and they will not be the same measurements if made from a different location.

What Einstein realised is that we use light to measure everything, astronomically speaking, therefore if light has a finite speed then that will affect our measurements. This is both profound and extremely important. Unfortunately, he didn't completely unravel it and his contemporaries were barely able to understand him, let alone advance on his work, and it has ended up in the mess we have today. But it can be unraveled quite easily, and all you need to do it is the definition of velocity.

We start out on the Earth. That is our reference frame because that is where the measurements are made. Whether we are talking about the age of each twin or the space craft on its journey, the measurements are made on the Earth (or starting position). Now, we can't actually see anything important by looking at the age of the twins, it is the journey that matters, not the start and end points. The short answer for the age is that they are the same age. Before and after the journey. Now let me show you why that is.

In essence, time does not slow down and length does not contract. They only appear to do so in our measurements. Our data is time dilated and length contracted, but the actual times and lengths are not. I will only deal with time here, as that is enough for this problem.

In order to see time dilation, we need some clock on the spaceship that is sending a signal back to the Earth. It does this by emitting a photon every 1 second. The receiver on Earth knows that the clock will emit every second and, ignoring Relativity, that is what it would expect to measure. However, light has a finite speed so it takes time for it to travel back to the Earth before it can be measured. That in itself just creates a time offset between emission and reception of a single photon.

The spaceship is traveling at the speed of light, though, so when it emits the next photon, it has moved 300,000km. That is 300,000km more that this photon has to travel than the last one did, so it will arrive later than expected. It will arrive 1s later than expected because it takes the photon 1s to travel the extra distance. So the receiver gets a signal at time N, and it expects another signal at N+1, but it actually receives it at N+2. Time has not slowed down, the source of photons has moved. That is all there is to it.

Now, let's have a look at the return journey. We are still measuring from the Earth and the first question is: What data do you expect to receive during the return journey?

The answer is: None!

We are now looking at a spaceship that is very far away and traveling towards the Earth. We assume it reaches light speed instantly so it emits a photon at the moment it turns on its engines. One second later it emits another photon, but the ship has traveled 300,000km during that second and the previous photon has also traveled 300,000km in that second. So the second photon is in the same position as the first photon when it is emitted. Every photon emitted during the entire journey is in the same location at every stage of that journey. The receiver will receive them all at the same time (along with the spaceship) and that is only once the journey has ended.

If the spaceship was not traveling at c then we would actually measure time contraction and length dilation. Each photon on the return journey has less distance to travel than the last photon emitted, and that would appear as time speeding up to the receiver. There is less distance between each photon and it is that distance that we measure as time.

You can see this in action in an app I developed at http://www.nevyns-lab.com/mathis/app/Re ... r-vel.html.

That app (which works in your browser, you don't need to download and run anything) only uses the definition of velocity and it shows time dilation. It only shows the first part of the Twins Paradox, but once you understand Special Relativity in this mechanical, dare I say physical, way, you can see what will happen on the return journey.

[webolife]

I'm having a problem with that logic... according to Einstein, the light being "emitted" on the away journey will travel away from the ship at "c" but also toward the earth at "c". If the ship is at velocity "c" away then the light signals should be "stopped" in space, but in Einstein's picture they are not; this is a logical contradiction, euphemistically described as a "paradox". Likewise, those signals being "stacked" together in the above description of the ship's return journey should be leaving the ship at velocity "c" --- No mater how you look at it, nonsense ensues if "c" has the properties endowed upon it by Einstein. If this were only a problem of measurement dilation and contraction, there would be no theory of relativity.

I'm with Roshi on this I think.

[Nevyn]

Webolife, you have given a single photon 2 different linear velocities. It can not have 2, only 1, so the photon can not travel away from the ship at c. It can only travel at c, irrespective of the ships velocity. Einstein stated that light is a special case. It always travels at c. You can not add the emitters velocity to the velocity of light. You must be misinterpreting Einstein if you think the light travels with a velocity relative to the ship. The important thing to remember is that lights travels at c but it doesn't need to be emitted at c.

The question to ask is: Light travels at c with respect to what?

With respect to its previous position. Let's say it starts at (0, 0, 0) and it has a velocity in the X dimension. Then, after 1s, the photon will be at (300,000km, 0, 0). If it isn't, then the speed of light has no meaning. If you allow actual time and length to dilate and contract, then the speed of light has no meaning either. However, if you allow measurements of time to dilate (and contract), then you have a logical framework with no contradictions that adheres to the definition of velocity.

I should also point out that in these scenarios, the Earth, or receiver, is assumed to have no velocity.

On the return journey, the photons will not be stopped in space, but they will be stopped with respect to the space ship. How could it be any other way? The photon is traveling at c and the ship is traveling at c, in the same direction. For every meter the photon moves, the ship moves the same meter. After 1 second, the ship emits another photon and that photon is now in the same location that the first photon is, at this point in time (not the original location that the first photon was emitted at and I am also ignoring the fact that 2 particles could not be in the same location for simplicity).

Even in this redefinition of it, Relativity is still important and needed. That is because all of our data is affected by Relativity and we must deal with that if we want to interpret that data correctly. We could get around it a little bit by using digital signals with the data encoded in it, rather than directly measuring light, but we still use light to encode that digital signal, and that signal will be affected by time dilation and it will manifest as a frequency shift. That is, if you expect a bit every ns then you will receive them either before or after that ns depending on the direction of travel. You can't get around it, just change what it affects.

Actually, you can get around it, in this scenario, by encoding the data at a frequency that subtracts the effects of the emitters velocity. Suppose our ship is traveling away from the receiver at 0.5c. It knows that if it emits a photon every second, then the receiver will receive those every 1.5s. So the ship actually sends them out every 0.5s. Now the receiver will receive them at 1s intervals. This allows many different ships to communicate with the same receiver because each ship takes care of dealing with the Relativity issues because the ship knows its own velocity with respect to the receiver.

[webolife]

I hear you Nevyn, and follow your thinking.
But Einstein's view was that light travels at "c" with respect to any observer, thus the observer on the ship "sees" the signal depart at "c" and I sitting at home here by my computer "see" that same light traveling at "c" --- "how can it be any other way" indeed?! That is the contradiction which is Einstein's relativity! I'm perfectly fine with Galileo's relativity, as that defines the real world of observation quite adequately.
The "c" problem is resolved for me by [my claim] that light has no [longitudinal] velocity. Acting instantly at both centroid and periphery of its field, vectored in the direction of the centroid ["centropic" pressure], light is rays [actually "beams"] of force [er, pressure]. Not infinitely fast, an oxymoron, rather it is a collapsing [contracting/compressing/decaying/entropy] field effect, an energy level drop at the centroid [or surface of the centroid, such as the dropping of an electron into lower energy state] detected by a frequency resonant sensor [photoreceptor/film/thermocouple/et.al.] at a peripheral point in the field.

[Nevyn]

I am of the opinion that we don't have to adhere to everything Einstein said (or Newton or anyone), we just have to make sense of it. Einstein was not very strict in his variable assignments and this has caused many problems since. He was dealing with a complicated topic, to be sure, but I think it has been over-complicated, for what-ever reason. I find it best to break things down to the lowest levels, which in this case is positions and velocities. That allows you to see things much clearer than high level abstract concepts.

The statement that light travels at c to any observer is just not physical. It is not possible. It is a contradiction and therefore false. But I can make some sense of it by changing it to light will be measured at c to a slow observer and that is because the speed of light is so large that the difference becomes negligible. The further you go or the faster you go, the less negligible it becomes. But you can't measure light from a distance, you can only measure light that comes straight at your measuring device. Therefore you can't measure the same photon from two different positions. We don't see light, it collides with our measuring device, which means there is no way to actually determine if two observers see the photon moving at c. It is not falsifiable, except through logic, reason and the definition of velocity, and therefore it is not scientific.

That's how I see it, anyway. Others can take it or leave it. I don't mind. I've made sense of it and managed to model it with only the definition of velocity and that produces time dilation and contraction and I have also modeled length contraction and dilation with the same premise. I'll take that over 'Einstein said ...' any day.

[webolife]

Now I am 95% with you.
I felt you were misrepresenting Einstein, which was likely true; you were just presenting your own take, which is quite akin in several respects to mine.
We cannot "see" light, for all light [incl colors] is utterly invisible, and cannot in any way be measured "along the way". Only a resonant detector can tell it is there. Furthermore, when it is detected, it is there, not moving somewhere. Femtophotographic processing presents an illusion of seeing light travel.

[Nevyn]

I am curious about what the last 5% is and also curious about your own thoughts on light. Do you have any links to posts I could read about your ideas?

[webolife]

Seasmith started this thread a while back dedicated to some of my ideas:
http://www.thunderbolts.info/forum/phpB ... f=8&t=5265
I've posted 1000s of shortish responses on other threads, not sure how to even begin to point you to them.
Maybe Lloyd can provide a link to a document I started with his help a couple years ago:
"Centropic Pressure Field Theory"
... Lloyd?

[comingfrom]

I've posted 1000s of shortish responses on other threads, not sure how to even begin to point you to them.

There is a way.

Centropic Pressure Field Theory site:www.thunderbolts.info