# tar

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## Posts posted by tar

### Dividing a sphere into twelve "identical" shapes.

Here is a toothpick and clay version of the twelve sections of the sphere, made up of two tetrahedra.

The yellow tetrahedra is one

the red,green and blue is the opposite

Note that the combination yields a cube and the center of each of the twelve diamonds is on the center of one of the edges of the cube.

### setting the Minkowski Spacetime model in motion

I think I am not clear on what is standing for what in the river analogy.

One of the confusions in my understanding of relativity is when distance is used in a spacelike way and when it is used in a time like way.

My solution is to consider…

My entry screen is confounded.  Even in word.

### setting the Minkowski Spacetime model in motion

the count or phase is similar to frequency in that each peak represents one count or tick

if there is a certain amount of ticks per second that is the frequency

my contention is that a light wave of a certain frequency does not change in reference to the universe

that is it is doing what it is doing regardless of who or what notices it

if you are moving in the same direction as the wave the ticks will be red shifted

if you are moving toward the light the ticks will be blue shifted

no time is warped

no distance is warped

### setting the Minkowski Spacetime model in motion

8 minutes ago, swansont said:

I'm unsure as to what you mean by "route dependent"

I know that if a clock moves, it runs slow relative to another clock, and that this is both (1) experimentally confirmed and (2) in accordance with the predictions of relativity

I don't care what you believe to be true. I want to know what you can demonstrate to be true.

I have a question about how you sync moving clocks.

for instance, if you sync a clock from here and the clock is 30 centimeters from here and you want it to read the same time when you get to it or it to you you have to send it the count on your clock and tell it to add a nanosecond to your count so that both clocks are reading the same proper time.

if you sync all clocks at the start of the experiment to read the same proper time, according to their distance from a master clock, then moving toward another clock you would see a blue shift but the lag in time would be gone by the time you were in the same spot.

Thank you Joigus for your time.

I got it a few times but there is looking back and not getting it.

I would explain, but a bot keeps preventing me.

### setting the Minkowski Spacetime model in motion

On 11/29/2021 at 7:37 AM, swansont said:

These statements are incompatible, because the equations of relativity show that length and time are quite clearly relative

Perhaps, perhaps not.

You believe time is route dependent.  I do not,

On 11/29/2021 at 8:04 AM, studiot said:

I am not sure how much you will find about vectors in Bondi's book, but the Einstein train experiments chapter is worth thinking about.

Here is another train experiment which shows some interesting things.

A man holding two bricks is travelling in a glass train. (Glass so he can see and be seen)

He holds them side by side, one just inside the carriage and one just outside by the window.

As he passes another man standing on a station platform he drops them both together.

It is illuminating to consider what each man sees about the paths of the two bricks.

the both bricks would fall in a parabola  for the guy on the platform and straight down for the guy in the train

I am unsure about the chapter where a boat is crossing a river at 5 miles and hour, pointed upstream so he gets to the shore across. Bondi says the effective speed is 4 miles an hour, but he confuses the amount of water traveled, with the distance to the other shore.  This is crucial to not get confused because time flows like a river.  You are carried downstream no matter what your angle of approach.  That is, the water you first were on is downstream by the time you get anywhere.  Consider a conveyor belt you would like to cross holding a marker touching the belt.  The line you make would be a diagonal line of a particular length, longer than the distance across.

In the various travels of Alfred and Charles, Hermann always resyncs clocks when the travelers are passing.  I think if you properly sync the clocks at the start, there would be no need.

### Dividing a sphere into twelve "identical" shapes.

Here is a balloon I made for my Grandson.

Not just any balloon but the whole of what I have been working on since the start of this thread.

The green marker shows a cube.

The blue marker shows a cuboctblahedron.

The red marker with the brown squiggles on it shows  a tetrahedron.

The red marker with the black squiggles on it shows an opposite tetrahedron.

Together the tetrahedrons make the twelve sections of the sphere.

The red line connects the center of the numbered diamond sections.

### Is the block universe just a whole bunch of world lines (from the elementary particles)?

Also, this discussion has pointed out the difference between a world map and a world picture.  A picture is what the world looks like.  A map is how the world is arranged outside your view.

before I take a trip I like to look at where I am going on Google Earth

I like to have a picture in my mind to compare against the picture I see while I am driving.

### setting the Minkowski Spacetime model in motion

On 11/22/2021 at 3:49 PM, studiot said:

I wonder, have you been following the discussion with another member about the geometric interpretation embodied in Minkowski ?

Relativity without time dilation or length contraction ?

That is Galilean or Newtonian relativity. The thread I linked to has got as far as that.

The problem with Galilean relativity and why it had to be abandoned , except at low speeds and locally, some of its predictions are in direct conflict with observations that late nineteenth century scientists made and subsequently more recent scientists have made to much greater precision.

It is too long to reproduce here but I can email an English translation  of the paper delivered to the 80th assembly of the German Natural Scientists and Physicians at Cologne in 1908, by H Minkowski, shortly before his untimely early death from appendicitis.

If you want a scan of the paper, let me have an email address that can accept jpgs of up 1M by private message.

I would recommend reading the paper as I think you would find it accessible (ie not too mathematical or high powered, no offence) he was a natural at explaining his points.

Thank you,

I am rereading and reevaluating the arguments and math presented in Relativity and Common Sense, A New Approach to Einstein, written by Herman Bondi and published 1964.    This, in an effort to answer your previous vector question.

I am not saying that the equations of relativity give you wrong results, I am saying that the definitions and assumptions and the dropping and adding of dimensions can lead one to incorrect mathematical interpretations.  In my imagination, I follow the travels of Alfred, Brian and Edgar, as they fly around syncing their watches upon meeting and sending out pulses every four seconds and following their pulses toward the next observer.  I am never satisfied, in the descriptions, that the situation cannot be understood WITHOUT any time dilation or length contraction.  In my interpretation, there is still private time and public time, or proper time, but HOW clocks are synced, and why is not done in what I consider a logical fashion.

In my interpretation proper time is the universal time I talk about and private time is the local now I talk about.  To me, the rest of the universe is experiencing only one thing at a time and that time is now.  Things that happened before everywhere have already happened and will not happen again in exactly the same combination, because things change with time.  Thing we see and experience in our local now are the effects of what happened before.  We see the images and feel the vibrations of the things around us.  Close things first, far things later, really far things never because we don't live long enough to see them arrive in our now.  But the past has already happened and the past constructs our present and the present of every other location.  Nothing  happens in isolation.  And the future has not happened yet, anywhere.

So please give me a little time to finish Bondi and try to learn some of the transforms so I can transform the transforms into my space.  I do not think the equations of relativity are wrong.

### setting the Minkowski Spacetime model in motion

Studiot,

Thankyou.

I have not completely translated all or any for that manner equations derived from the original definitions of Minkowski space.  I will endeavor to seek out a particular said equation with vectors and such and show that the relativity equations derived from original definitions would be equally obtainable using the dynamic model that I am using without deforming space or dilating time.

Regards, TAR

I am a big fan of geometric solutions.

MigL,

I have been trying to understand relativity, without requiring time dilation and length compression.  I am not using the Minkowski diagram as the Minkowski diagram.  I just noticed my thought has the future below and the past above, so it might be hard to true everything up in terms of equations, but I was trying to use a model or picture everyone has in their head as a basis for discussion.  Since the Minkowski diagram is used to show how space deforms and time dilates and I don't require space or time to act in that fashion to comprehend relativity, I am thinking that things might work out mathematically with redefinitions of here and now and then and there and how you get between the two.

Regards TAR

### setting the Minkowski Spacetime model in motion

Rather than defining positions on the diagram as events, define the diagram as representing actual reality in the following manner and then locate the event in the resulting dynamic model.

The hyperplane going through the origin is the present of all space, three dimensional space depicted in two dimensions, .   This hyperplane falls through the dynamic model at 1 sec per second along the z axis.   All past events for the observer at the origin existed above the plane but are visible as photons coming in from all directions, shown on the diagram as the upper light cone. The lower light cone represents photons or signals going out, at light speed from the observer.  These light cones will intersect the falling hyperplane in increasingly large circles, representing the spherical shell of photons.

Movement toward another location in space results in decreasing the time and/or distance between the locations. Both locations fall through time at 1 sec per sec and light travels always at C.

### Size of an event in Spacetime

bufofrog,

I don't understand why critical thinking is banned on this board.

There is usually more than one way to explain a thing.  I do not accept foreshortening, because it deforms reality.  Pi for instance is not effected by velocity.

However if your spaceship traveling at close to c traverses a circle, the circle becomes an ellipse with no cause and effect noted, or any concern for whether the circle becomes an ellipse for everybody, or just for the moving observer.  If it happens just for the moving observer then the distant clock just appears to click differently, it does not actually tick differently.   If you apply common sense to any observation, hold time as clicking off equally everywhere at once and factor in the light travel time between the two ends of the experiment, and the position of the observers and the position of the experimenter, you can resolve differences in observed time without requiring the universe to do magic tricks.

### Size of an event in Spacetime

Not going to work Bufofrog.  You wind up thinking the universe is weird, time dilates, distances shorten and there is dark energy and dark matter that we never needed before to explain mainstream physics.

but fine, go ahead and muddle

### Size of an event in Spacetime

Swansont,

That is your loss to lock that thread topic.   I cannot relay my understanding of relativity without using the two nows.  You use them all the time.  i am in no way saying the equations of relativity don't work.  I am saying I understand relativity and I can explain the math without requiring space to deform or time to dilate.

Regards, TAR

### Size of an event in Spacetime

On 11/10/2021 at 7:22 AM, swansont said:

I've worked with copper, fiber and free-space transmission. The concept is the same.

And once again I will ask if you have example of this not happening when it matters. Because I don't have any — people working on experiments that require precise measurements do these things, otherwise their experiments don't work.

You're pointing out the obvious

Unlikely that a supernova event 10000 LY away is still occurring if we're just getting the photons now. We know how long supernovae last, and it's much less than 10,000 years.

Let's say it was 10,000 LY away, and the star was 30 light-seconds across (which is about 9 million km; the sun is about 1.4 million km across) A year is a little over 3 x 10^7 sec, so the distance ratio is 30s *c/10^4 * 3x10^7 *c

Ignoring the size gives an error of a part in 10^10, so in some cases this is meaningless — if your experiment has less precision than this.

The bottom line is that the speed of light is a known phenomenon and physicists aren't stupid, and your premise is basically that they/we are (and we see similar "point out obvious things" phenomena in discussions on evolution, too).

On top of that, we have peer review, so even if one particular experimenter somehow ignored the effect, others would notice when it came time to publish results, either through peer review or in responses to the publication, which would be quickly retracted from any reputable journal. So unless you have actual examples of people screwing up by not accounting for light travel, this is pointless, and just an exercise in you demonstrating that you have no familiarity with how these experiments are conducted.

understood,  but I am not calling anybody stupid.  I agree the things happen the way people see them happen and report on them and figure them and such, but the assumptions vary.  For instance you say the super nova is no longer happening.  In one sense it is, because we are seeing it.  In another sense it is not because it happened in that location in space a long time ago and something else is happening now in that location in space.  But in order to understand this obvious fact about the universe you have to consider there are two nows and you told me that is not how it is...but that is how it is, so what is obvious?

studiot I take your point about the term wavefront, but for this discussion the size of the wave matters too, in the sense that the size of a sine wave includes the measurement from peak to peak I think or valley to valley.  But where does a wave start? At the zero point.  When a photo is created by the drop of an electron from one energy level to another, this is a process or an event so to speak that in not instantaneous  would argue, but happens over a short period of time.  The wave edge starts as soon as the electron "starts" to fall and the whole fall creates a photon of said energy and frequency.

### Size of an event in Spacetime

Understood

did you e er work with fiber optic cable or was it copper

I still don't think the logic is always sound.

That is, one person might be making assumptions the other is not and vice a versa.

What happens in the environment of the Earth, pretty much happens within the time it takes a light signal to get from one place to another.  That is, we more or less can consider ourselves in the same moment.  It takes time for a signal from our eye to get to our brain and such, so nothing is immediate.  There is a fudge factor we commonly apply to consider something happening "at the same time", but for the sake of this discussion in terms of the size of an event, I think it worth while to consider the real difference between one side of an event and another.  For instance, when someone says the event is happening now are they talking the leaf starting to fall, or the light striking the ccd recording the event?

Cosmic events are even harder to agree upon the event size, because in a real sense, if you are just now seeing a super nova, it has both already happened, maybe 10 of thousands or millions of years ago, AND is actually still occurring because a photon from it, just hit your instrument.

to relegate a super nova to a dimensionless point in a spacetime manifold would be sort of meaningless

### Size of an event in Spacetime

Perhaps I am worrying over nothing, if this is already taken into account, but to have a T=0 you have to know if that is according to the event location, the experimenter's location, or the coincident detector's location.  in the experiment it would be required to know the distances between all three and how their clocks were synced.

for instance if a green leaf is falling the position of the leaf is different for someone a meter away and someone 2 meters away

a milli second after the first guy sees it fall the guy standing a meter behind him sees it fall.   When the second guy sees the first wave edge the first guy is seeing the hundred millionth wave edge, if the wavelength of green light is 500nm.

### Size of an event in Spacetime

23 hours ago, swansont said:

Who is CollinJ and why is this relevant?

Under what circumstances will this matter? Ijf I am driving my car and say that I will arrive at some time T, does it matter that the front of my car arrives a fraction of a second earlier? No measurement has infinite precision.

CollinJ was another poster in this forum that suggested he found a way to unify the big and the small.

I did not want to hijack his thread nor associate myself with him as I thought such would prejudice those who are prejudiced against my thinking on this against his thinking on this.

Where I see it matters in what we experience about the world and its behaviors, is that we "see" using photons.  These little creatures are neither wave nor particle but have attributes of both.  A particle is hard to pin down, as one cannot determine both the location and the momentum of a particle.  You either know where it is or you know where it is going and where its been and how quickly it seems to be making the location change.  Or the photon can be thought of as a wave which has an amplitude and a frequency.   In both cases time and distance are required in order to describe the photon.    Since we "see" using photons, the size and duration of the experiment is important to consider, because there is a light travel time to consider from one end of the experiment to the other.

### Size of an event in Spacetime

CollinJ simple unification theory has an analogy to my problem with spacetime events and possibly has similar resolutions, but I did not want to associate myself with collinj as that would be a handicap for CollinJ.   However we both have the same thought in terms of seeing something that goes against established theoretical math, and this morning I think I noticed the reason.

In relativity a spacetime event is defined or represented as a point in a manifold and transforms are made between two observers of the point in two different inertial frames.

The problem I have with this is an event is neither a point in space because it has a size, nor an instant in time, because it has a duration.  By definition an event requires both a change in a situation over time and a volume of space in which to occur.  So it would be an errored assumption to relegate an event to a dimensionless point.

Perhaps resolving the size and duration of the "point" would square or "cube" the equation to match reality.

### Relativity equations are correct but possibly for different reasons than dilation of time and shortening of lengths.

I was asked to explain what a stationary observer would measure concerning the clocks and distances of an orbiting observer.  I would need, to properly predict, to know the distance of the third observer and the angle of view of the experiment.

And I would have to be allowed to use the two nows. One universal now where everything only happens once. And one local now experienced by each of the separate observers.

Additionally it would be useful to establish an external clock, like a pulsar and establish a starting count relative to that clock for each of the three observers.

and i would have to know the distance and position of the pulsar relative to the experiment and experiment observer.

Consider an observer right now on a planet orbiting alpha proxima or some star 3 to 5 light years from here, looking at the Earth with a really powerful telescope.  If they would look at my dad’s house in NJ they might see him leaving the house or sitting outside.   However in our local now my father has passed away.

The many local nows are separated by distance which translates to time, as the Mars rover has already done, 24 minutes ago, anything we see it do now.  But my contention is the Mars rover is only doing one thing at a time and it is doing something right now.  The signals that recorded that event will reach us in 24 minutes, or however far away Mars is from Earth right now.  Mars is actually 24 minutes advanced in its orbit from where we see it, but to grasp that you have to consider two nows.

### Relativity equations are correct but possibly for different reasons than dilation of time and shortening of lengths.

18 hours ago, swansont said:

What is your theoretical and experimental evidence to support this?

doppler shift is well studied

17 hours ago, Bufofrog said:

What do you mean the speed of light remains the same?  Do you mean the speed of light as measured from the moving frame is still c?  if so how is that possible without time dilation and length contraction?

I mean the photons do not know who is receiving them.  They move along at the speed of light no matter what.  Consider the two nows idea and you will understand how something can look blue shifted without the frequency of the initial vibration of the source being slowed or quickened.

Consider again the pulsar thought experiment.  Using the idea of two nows, one local and the other universal, there are in actuality all the waves of light the pulsar is putting out, right now in space, that we will see for the 10 thousand years or however far away the pulsar is.  If you move quickly toward the pulsar you will experience the pulsars beat as speeding up.  It has not sped up.  Your space craft has not shrunk.  Space has not deformed.

16 hours ago, StringJunky said:

Tar, you work towards understanding the theory before trying to offer solutions. I'm surprised you  are even questioning this, given how long you've been here and the evidence that has passed before you.

understood

but I am not discounting observations

I am understanding what is going on, and providing a way to understand actual reality without requiring it be wierd.

17 hours ago, Bufofrog said:

What do you mean the speed of light remains the same?  Do you mean the speed of light as measured from the moving frame is still c?  if so how is that possible without time dilation and length contraction?

a bot or watcher is confounding my entry screen.

16 hours ago, StringJunky said:

Tar, you work towards understanding the theory before trying to offer solutions. I'm surprised you  are even questioning this, given how long you've been here and the evidence that has passed before you.

I have tried, but time dilation and length contraction do not work out in my thought experiments.

14 hours ago, MigL said:

That is incorrect. You were using incorrect science.

Frequency is cycles per unit time.
The 'space' these cycles occur in is actually the time domain.
If you shorten the TIME that these CYCLES occurr in, you get a blue-shift, or increased frequency.
So yes, if you detect a frequency change between two heights in a potential well ( from the same source ) it has to be due to a change in the duration of the time unit between each cycle. Either a lengthening ( dilation ) or shortening ( contraction ).

Again you risk being shut down for using incorrect science.

What does the term incorrect science mean to you.

That I don't see the world correctly or that I don't adhere to the assumptions and applications of accepted theory.

I think the universe makes sense.  Excepted theory requires the universe be wierd.

Whose view is more sensible?

14 hours ago, MigL said:

That is incorrect. You were using incorrect science.

Frequency is cycles per unit time.
The 'space' these cycles occur in is actually the time domain.
If you shorten the TIME that these CYCLES occurr in, you get a blue-shift, or increased frequency.
So yes, if you detect a frequency change between two heights in a potential well ( from the same source ) it has to be due to a change in the duration of the time unit between each cycle. Either a lengthening ( dilation ) or shortening ( contraction ).

Again you risk being shut down for using incorrect science.

I don't think you can get shut down in a science forum for being a skeptic.

I am after looking at the experiments from a common sense point of view where everything adds back correctly.

14 hours ago, Ghideon said:

Suppose an observer B is in a circular orbit around an observer A. Note that this means A and B are separated with the same distance at all times. Questions:
1: Per your ideas, will a clock at observer A remain in synch with a clock traveling with observer B?
2: Will A and B agree on the measurement of the length of B's orbit? (A and B measure in their respective frame of reference)
3: What is the mathematics that gives the answer to questions above?
4: How does 1-3 compare with established models in relativity theories?
5: How is red shift or blue shift involved?

I tried to answer but was confounded by the entry screen again.  Was a good answer, by the way, but was deleted.

it requires the universal now to parse that experiment and requires a knowledge of how far away the third observer is from the experiment and at what angle he is viewing the situation

### Relativity equations are correct but possibly for different reasons than dilation of time and shortening of lengths.

I got shut down with the two nows idea because SwansonT thought I was going against mainstream science.  I am absolutely not going against the results of the experiments.  GPS works.  What I am suggesting is that you can arrive at thre same equations without distorting space and time.  Most  clocks these days, like the heated Cesium ones work on the basis of a certain frequency of light being given off by a certain drop of an electron in the Cesium atom to a lower energy level.  This particular frequency is always 9,192,631,770Hz.

Now suppose you are traveling fast toward this light.  It will be blue shifted.  The space the waves exist in will appear to be shortened.  The space however is not shortened. The speed of light remains the same, the frequency increases.  Time does not speed up or slow down.  Space does not lengthen or contract.

### Requirement for two "nows" to grasp the idea of Simultaneity

9 minutes ago, tar said:

why yes

relativity equations would have the traveling twin not age as much as the stay at home

the pulsar cycle count experienced by both the stay at home and the moving twin would be exactly the same, thus invalidating the relativity equation

any differences in the clocks of the moving and stationary observers can be explained by red shift and blue shift where the frequency of light changes, not distance or the speed of light or time

Matter of fact, if you travel at relativistic speeds the universe in front of you is highly blue shifted and is hitting you with tremendous energy and the universe behind you is highly red shifted and visible light is hitting you as microwaves and radio waves.  Gamma rays coming in your front window, radio waves out the back.  On the way back the traveling twin will see the approaching clocks running fast, making up for any slow count on the way out.

This effect, which I  untis an obvious consequence of high velocity toward or away from an electromagnetic wave is a new theory evidently because you say I am wrong and I am not. I believe that is the way the universe works.

It is hard for me to accept a heat death of the universe because the whole universe is sending photons toward every other part of the universe.  Said photons don't disappear until they hit another atom an raise an electron into a higher energy state.  Then as atoms do they try to lose the energy by emitting a photon.  No atom can reach a ground state because the rest of the universe is sending its energy in to it

so i do not think the universe will suffer a heat death

3 minutes ago, Phi for All said:
!

Moderator Note

OK, help me out here. You're not asking questions anymore, you're claiming "relativity has failed in X" without supplying any science to support yourself. You know you can't just wave your hands or appeal to incredulity. This should be moved to Speculations, but that won't help if you aren't willing to offer more support. You're soapboxing pretty much here, and ignoring replies that you've asked for.

If you want to stay in mainstream, listen to the mainstream replies you're getting and respond accordingly. If you want to defend your beliefs in Speculations, then please provide some science to support the stances.

How is blue shift and red shift not science?

I will be quiet.

You are not answering honestly.  You are answering with the relativity equation, like it is more real than reality.  Reality makes more sense than how you say it works.

### Requirement for two "nows" to grasp the idea of Simultaneity

2 hours ago, swansont said:

Relativity is why we think there is dark eneregy and dark matter. What has failed to happen is for some new theory to emerge to explain these things.

How does it fall to relativity to propose other realities and other dimensions?

What "I" have is a theory that has passed every experimental test thrown at it. What have you got? From this perspective you have nada.

That was tried early on. Clocks were left uncorrected and were observed to not be running at the correct rate. The relativity corrections were correct to about 1%

Why would there be "needed corrections" if relativity were wrong?

We already know and adjust for light travel time; it's part of clock synchronization. "Now" is not a value that ever gets used when you try and quantify such things. "Now" is pretty useless for a wide swath of applications of relativity. That you are not aware of these applications doesn't make them any less real.

I don't see what the pulsar "experiment" has to do with the validity of relativity. You have a distant pulsar, you have a bunch of pulses that are en route. Is there something more than that?

why yes

relativity equations would have the traveling twin not age as much as the stay at home

the pulsar cycle count experienced by both the stay at home and the moving twin would be exactly the same, thus invalidating the relativity equation

any differences in the clocks of the moving and stationary observers can be explained by red shift and blue shift where the frequency of light changes, not distance or the speed of light or time

Matter of fact, if you travel at relativistic speeds the universe in front of you is highly blue shifted and is hitting you with tremendous energy and the universe behind you is highly red shifted and visible light is hitting you as microwaves and radio waves.  Gamma rays coming in your front window, radio waves out the back.  On the way back the traveling twin will see the approaching clocks running fast, making up for any slow count on the way out.

### Requirement for two "nows" to grasp the idea of Simultaneity

4 minutes ago, swansont said:

We use such aids to understanding in a lot of ways, and in lots of disciplines. As they say, the map is not the territory. But maps are useful.

But where has the science failed? Do you have any concrete examples of relativity not working as advertised?

Again, you are projecting your own lack of comprehension on to others. We may not know everything, but that's very different from saying we know nothing.

I believe relativity has failed in constructing dark energy and dark matter from the motion of a super nova in another galaxy.

I believe relativity has failed in proposing other realities and other dimensions that have no bearing on our reality.

I believe relativity has failed in causing people to think the universe is strange and not comprehensible, when everything actually fits together and works quite flawlessly.  I do not yield to you that yiou have it right and I have it wrong.

57 minutes ago, swansont said:

It does if you want to do anything related to time and distance.

Perhaps the most famous example of time dilation's impact on the modern world is that it has to be accounted for in order for GPS to work. Without it, no GPS. So it would seem that it does have an impact.

We can't measure length at the same precision as time, but there are examples of length contraction having an impact, too. Certain high-energy collision physics must take it into account. We have the well-known muon decay example. It's critical in order to explain why parallel, current-carrying wires exert forces on each other.

I think this translates to it makes no sense to you, and you don't know what spacetime is, but to project that onto other people is quite something.

Perhaps,  but I try and read and understand QED and GR and SR stuff.  I have developed my own understanding of what makes sense and what does not.  Usually, if something is true it is true  in more than one way.  That is, you could sync GPS clocks without using relativity equations, using only distance and light travel time.  I f the orbiting clock runs slow or fast you apply the needed correction.

40 minutes ago, swansont said:

Muon decay has nothing to do with this beyond being another example of relativity

My point was that you can explain the magnetic force with only the electric force and relativity. Because, in fact, all the classical magnetic force is is an electrostatic force viewed from a moving frame of reference, via the relativistic transformations. But you knew this, right? Because such criticism has to be based on a thorough understanding of relativity

Physics isn't attempting to explain reality. It's explaining how nature behaves.

well suppose you have a pen pal on a planet circling a nearby star, where light travel time separates your nows by 3 years. When you get a message from her you know she sent it 3 years ago.  If she was 36 when she wrote it, you know she is 39 now.  Two nows.  When she gets your reply she will be 42.

She is, in reality only one age, as you are only one age.  And you increment your years at the same time.

20 hours ago, beecee said:

Start explaining. Start by explaining to me why we need to plug in SR with regards to GPS satellites, and then the muon effect.

"c" is actually the speed of light in a vacuum and is obviously constant. It has been shown irrefutably [not withstanding your yet to be announced examples to the contrary] that it is space/length and time that are invariant. And of course, at least in my puny mind, as we go faster, time slows down [dilates] while "c" is constant. Just as space and time are interchangeable, so to is length contraction and time dilation.

No it doesn't. You can never be sure that the next pulse will ever happen. We see Alpha Centauri tonight in our now. That "now" happened 4.3 years ago from the FoR of Centauri. There are many many nows that will see different things. My "now" when I see Alpha Centauri tonight is not the "now" of any planet orbiting Alpha Centauri, because that "now" does not exist as far as I am aware, until I receive information [light] about it.

How can you know you will see them later?

Well the correct part is that yes, everytime we look into the night sky, we are looking into the past. That literally means that it may not actually be there. We have no information about their "now".

Yes but our now includes light from alpha Centauri which it has for many past nows.  Although we can not be certain there is not a gamma ray burst that will hit the Earth on Tuesday on its way, we can be absolutely sure that in our now that occurred a minute ago, there was light from Alpha in space a light minute out because we just saw it.

### Requirement for two "nows" to grasp the idea of Simultaneity

19 minutes ago, swansont said:

It does if you want to do anything related to time and distance.

Perhaps the most famous example of time dilation's impact on the modern world is that it has to be accounted for in order for GPS to work. Without it, no GPS. So it would seem that it does have an impact.

We can't measure length at the same precision as time, but there are examples of length contraction having an impact, too. Certain high-energy collision physics must take it into account. We have the well-known muon decay example. It's critical in order to explain why parallel, current-carrying wires exert forces on each other.

I think this translates to it makes no sense to you, and you don't know what spacetime is, but to project that onto other people is quite something.

could you describe spacetime, using space and time as the a priori understandings?

I do not understand Chinese, although a 3 year old Chinese kid does.

That does not mean I do not understand reality.

Math is a language.  One thing stands for another.

My question to you, is can the forces between two wires be explained with magnetic and electric fields, without using muon decay?

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