It is the same as my OP stated...

But I will expound a little on the Two Truths being told or held to, 'simultaneously'.

From 'Earths Rest Frame' we see/detect light/ photons traveling specified distances at 186,282.4 mps over specified times, depending on that distance.
So, in that frame, light is NOT 0 distance 0 time...we never use light in it's own frame there!

There is NO "Space/Time diagram" that can be done for that "Earth Rest Frame" observer.

We absolutely know that part is "REAL"



For all SR observers, even the stationary/rest frame observer, a "Space/Time Diagram" is done, and in the Local Neighborhood, it makes 0 sense to do so.

SO, there IS NO WAY to get the "Now" of the SN in M31 to match our "Now" here in the Milky Way....then...

_____________________________________B____________ _______________



------------------------------------------LS



_____________________________________A____________ _______________

The halfway LS making A and B's clocks both read 0 at the same time is automatically meaningless to match A and B's 0's to their "Nows"...

That is very self evident and so simple it just seems that it has to be wrong to you guys

__________________
RussT
________________________________
Everything is, as it should be, otherwise, it wouldn't be!

And it absolutely has nothing to do with SR, which relates observations by observers in relative motion.

The whole method that you described is good to have the clocks of both A and B to have the same starting point (that they tick in the same rate is a given because A and B are at rest from eachother). Because they have the same starting point, and because they made the deal that B would send a signal to A when the synch signal arrived, A can now use her Δt on her clock to calculate her distance to B. It's like in movies where the team leader says, okay it is oh-threehundred hours on my mark, 3, 2, 1, mark.

__________________

Any comments in glorious red are to be considered in ModeratorMode.


善數, 不用籌策 (shàn shù, bù yòng chóu cè)
He who is good at counting, uses no counting tools
“A good scientist has freed himself of concepts and keeps his mind open to what is”
道德經, 二十七 (dào dé jīng, 27)

"Simultaneity" of first light there to absorption here What's that supposed to mean? You do seem to labouring under some gross misconceptions about what SR says.

What, precisely, do you mean by the now of some distant event to match our now here?

I thought you already agreed that you obviously can't see things as they happen, but only after they happen. But again you seem to be saying that if something happens at B at t=0 then someone at A should see it at t=0 too if they are synchronized using the equidistant light source.

__________________
There are 10 types of people in the world. Those who understand ternary, those who don't, and those waiting for a bus.
If logic doesn't work, then surely it does.

We dont understand why you think that SR says that there is simultinaety.

All SR would say in the case is exactly what you describe. It allows you to figure out exactly what you state, only it allows you to do it with moving objects in addition to stationary ones.

ALL SR says in the case you describe above, is that when you see the sync light, then 2 million years later when you see the supernova, you can determine that the supernova happened when the sync light arrived at its location. Or, if you wish to reverse it, if you know that when the sync light reaches you, the supernova will occur, then when you see the sync light, you know that in two million years you will see the supernova.

In otherwords, it gives you a way to mathmatically figure out exactly what you said.

That is all it does

In ANY rest frame, the speedof light is c, not just the Earths.

No one uses a photon's rest frame for anything, ever. It is a meaningless frame.
If it is REAL, we can make a spacetime diagram. That is what a spacetime diagram is.

The moon would be about a second and a half away, the sun 8.5 minutes, alpha centauri 4.3 years. Or if you prefer in lengths, the moon is about 450000km, the sun 150000000km and alpha centauri 4.3 light years.

That seems to be a perfectly functional spacetime diagram to me.
Seems to me that I explained this very thing to you a few posts ago. SR dosent say that syncing the clocks makes our now and their now the same, it says that our now and their now are different by d/c, where d is the distance between the two nows. Like I said in my last post, if we sync the clocks and a supernova happens at the same time in Andromeda as when the sync pulse reaches Andromeda, we can figure out that the sync pulse and the supernova occured at the same time, in Andromeda. Any observer in the Milky Way will say the two times were two million years apart.

SR acts exactly like you say it dosent. As a matter of fact, you dont even need Einstein. Given a constant speed of light, Gallileo would have said exactly the same thing 400 years ago.

What are you on about? You are trying to tell me that 2 people at x distance apart can't meet half way between them? You must be high.

If I measure the distance to you as x and you messure the distance to me as x and our clocks are synchoronised then we can be concidered in the same reference frame. It doesn't matter if we are 2 feet apart or 2 billion ly apart.

At that point all we have to do is accelerate and slow down at the same rate. We don't even have to travel at the same time.

I'll end this with another scenario.

What the hell is "instantaneous constant speed'? Do you mean accelerating to .5c instantantly? That would make the calculations much easier to do but I won't do that but then I won't spend the time to do the full calculations as they really don't matter. You'll need to point out where SR will break down and you and I wouldn't have the same time on our clocks.

It doesn't matter if they both go at the same time. All that matters is the fact that they accelerate at the same rate.

Are you worried that at the Planck time scale they will not be the same?


OK here is the scenario. Please indicate where you think SR breaks down.

What exactly will their clocks read? You can spend the time doing the calculations.

roughly their clock would read 400 hours while accelerating and declerating for a total of 800 hours then their travel time while a .5c, relative to their initial rest frame, would be about 43 years 3 months and 10ish days

If you believe their clocks would not read the same when they meet at the 3rd location then please...explain why and provide your math.

I think that RussT's problem is that he thinks that the concept of simultaneity comes from SR. The fact is, Russ, SR comes from simultaneity. Simultaneous events in inertial frame A are not observed to happen simultaneously in inertial frame B if there is relative motion between frame A and frame B.

As explained on pg. 1272 of my textbook from my physics 3 class "University Physics" by Young and Freedman, What SR does give us is a quantitative relationship between time intervals in different coordinate systems.

__________________
I don't ask stupid questions. I just make stupid statements!!!
DETAILS: Where the Devil waits to ensnare the unprepared!
Remember. Just because I'm sure doesn't mean I'm right.
Experience is a wonderful thing. It enables you to recognise a mistake when you make it again.

RussT,
To summarise:

1) Light in a vacuum, when measured in an inertial reference frame, always travels at a speed of 299792458 m/s

2) The Lorentz invariant commonly referred to as the "proper time" for any light-like interval is always equal to zero.

3) When we observe a spacetime event (seperated from us by a vacuum), we always see it as it was d/c earlier, where d is the distance, and c is the speed of light in a vacuum.

4) When we hear a noise from some event through the air, we always hear it at it was d/va earlier, where va is the corrected speed of sound in air.

5) Given the above, you can determine the distance to an object by measuring the time it takes for a flash of light to travel from the observer to the object and back again (via reflection.) d=t_tot/(2.c)

6) Also, from the above you can then determine how delayed the image of the object is, and hence take that time delay into account when assigning a time to events that occur at that object.

RussT, is there anything missing or incorrect in what I have stated?

How does any of this invaildate SR?

That certainly is not 100% of you guys .. at least one begin to AWARE of the forbidden Fruit in RELATIVITY... What if NOWS are what Actually-Occurring ...

To explore this a little further, with MOTION introduced:

Assume mother produced clones and milk, clones are sent away non-accelerated, each carry this QESS.
A meal of milk would be serve every 25 years to one of those who reach 25*n year old.

At n*25 year+1 sec, mom send a QESS signal .. Who's qualified for the milk ... and beacon back?

Who will get the milk ?

Lesson: not all Nows are the same, unless it is "the same place at the same time ----- the one that have zero distant from the Mon would have the milk ! " ....Introduction, THEORY of NOWs .

----------------------------------------------------------------------
Further more, light's internal structure, as an energy, or as hyperspace geometry is not satisfactorily ready to address OP, ie to tackle SR and the subsequence questions, just for fun:

To open this up a little bit more:
All form of Energy is an expression of Curvature, or it's inverse, a LENGTH ... that length^2 won't change as long as the energy is conserved.... in 11th grader's word, projection of this vector to your TIME axis, when zero .... this Energy is commonly called light.

The Energy to become light ? funny, it's just the light energy.

RussT, Sorry but I really have not idea what you are trying to say. First of all, the scenario has absolutely nothing to do with SR. Secondly, every point in the universe will have a different "now", if "now" is defined as when the photons from the event reach the observer.

__________________
______________________________________________
“He who asks a question is a fool for five minutes; he who does not ask a question remains a fool forever”
Chinese proverb
"All you need in this life is ignorance and confidence - and then success is sure." - Mark Twain.

And I still have an issue with this definition of now. If we restrict ourselves to terrestrial scenarios, if I close my eyes then all of these "Nows" are now defined in terms of the speed of sound, as hearing is now my primary method for determining what is going on in my environment.

We are still waiting for RussT to explain what the problem is with SR, but I'm now doubtful that he can or will.

Geezzzzzz, how many times do I have to show that everyone in this thread and KenG in the other thread is saying that it MUST be 0 distance 0 time when using SR>>GR...and JTsang is flat out saying that ALL "Nows" for us here on earth/Milky Way, are where the event actually happens.

And here Northern Boy, with 2 Degrees, had to actually do this wrong, to get the simultaneity he thought he needed!!!

Korjic, you can see that he did this wrong....right?

And once again, I will say that SR doesn't do this...SR doesn't do specified "Light Travel Time" over specified "Distances", and you even agree with this in the Bold...you dont even need Einstein..

And in Post # 181, at the top of this page you say...

__________________
RussT
________________________________
Everything is, as it should be, otherwise, it wouldn't be!

Yes, that is exactly what I am saying! Every observer does see his own light, in straight line motion, accept for the rare occurrance where it may be curved do to it's close proximity to a massive body, from any event or luminated object which travels at a Constant velocity of 186,282.4 mps.

In fact let's use another example...

If you and I are right on the equater of the earth, with you on the equater in Africa, and me on the equater in South America, let's just say that is 10,000 miles, and a satelite in geosynchronous orbit halfway between us is shining a bright light right at each of us, is there any way, that are "Nows" could be considered to be 0 distance in 0 time? Let's even say we are both high enough on a mountain where a light source could go straight from you to me?

Is there an "alien in a spaceship" traveling at "c" bringing our distance between us to 0 in 0 time???

__________________
RussT
________________________________
Everything is, as it should be, otherwise, it wouldn't be!

Then ALL of the lightning strikes on earth would be hitting you//

And I still would like to know where the Black Hole is that is hooked to your 'shortcut path' for light/photons to reach us?

__________________
RussT
________________________________
Everything is, as it should be, otherwise, it wouldn't be!

Tusenfem, why aren't you correcting this and showing Wayne where he has gone wrong here?

If this were in Q&A, and a newbie was trying to show this, and IIRC, I have seen you cover this point before, but besides just you, KenG, Publius, Grant, etc, would be covering that "According to Relativity", if you are accelerating, your path is a curved path, not a straight line motion, so if you were accelerating from Alpha Centauri and I was accelerating from earth............now tell me where we would meet?

So, no I am NOT high........been clean and sober for 12 years now. I even tried to warn you in a previous post that there was a problem with your scenario.

Now, my take on this, is that it is completely and utterly undefined, as to 'how much curvature' your path is, based on different accelerations.

Besides being an ad hoc rule....the right hand rule, you don't really know which way to really curve at all.

If you are accelerating at 1 G, does your curved path match earth curvature? I don't believe there is any determination at all about speed VS curvature.

And, how fast do you need to go before your path is so curved that you are going in tighter and tighter circles that at "c" your path is just like the event horizon of a Black Hole or spiraling down to 0?

__________________
RussT
________________________________
Everything is, as it should be, otherwise, it wouldn't be!

Exactly, and this tells me you did not give any consideration what-so-ever to the first part of my OP.

__________________
RussT
________________________________
Everything is, as it should be, otherwise, it wouldn't be!

But that definition of "now" is not related to the normal usage of the term simultaneos in SR. If we continue in this direction we'll be arguing about trees falling down with no one being there to hear them.

Again, what has this to do with a flaw in SR?

What do you mean by "SR>>GR"?

You do realize, of course, that this example has absolutely nothing to do with SR?

Did you even bother to read my last post?

But, to address your example. You and I would see the light from the satellite at the same time and if we had designed this experiment, then we would agree that we saw the light at the same time. If you had a mirror to reflect your light to me, I would see that reflection some time after I saw the light from the satellite. If I measured the time between when I saw the light from the satellite and the reflection, then I could determine how far apart we are. Again, this has nothing to do with SR.

However, if an alien were traveling past at some significant fraction of c at the time the light flashed from the satellite, this observer would not agree that you and I saw the flash at the same time. This situation is what SR deals with. Notice, please, that I make no mention of synchronized clocks.

__________________
I don't ask stupid questions. I just make stupid statements!!!
DETAILS: Where the Devil waits to ensnare the unprepared!
Remember. Just because I'm sure doesn't mean I'm right.
Experience is a wonderful thing. It enables you to recognise a mistake when you make it again.

What you are saying here is that if an alien in a spaceship happens to travel a c speed, then distance shrinks to 0 and time stops. However, it is impossible for a spaceship to travel at c speed, since this would take an infinite amount of energy to reach c.
Our distance does not shrink to zero for us, neither does our time stop. It would seem to us that his clock has stopped. As the spaceship approaches c speed, the alien would have the impression that from his perspective the distance is shortening, though his perception of the passage of time remains the same. However, he would never be able to reach c, and his time will continue to tick normally for him.

__________________
______________________________________________
“He who asks a question is a fool for five minutes; he who does not ask a question remains a fool forever”
Chinese proverb
"All you need in this life is ignorance and confidence - and then success is sure." - Mark Twain.

I think you are confused about the scenario. We are in the same rest frame and because of the distances we are also in the same gravity well. So why don't you think we couldn't meet 1/2 way between us?

Yet you won't point it out. Please explain, supported with math, why you don't think it is correct.

Do you not read? My scenario explicitely said how both you and I accelerated. Where do you get "different accelerations"?

You do know acceleration does not care about direction correct? That is the only difference between the 2 accelerations. The vectors are just opposite. That is it.

You know what...SR tells us something interesting about this scenario too. After you and I have accelerated to .5c

Given the V' = V₁ + V₂ / 1 + V₁*V₂/C²

V' = 1/1.25c or V' = .8c
IE we would see each other approaching at .8c

WHAT? you are VERY confused aren't you. By your account we couldn't ever get to the moon let alone thread a satelite through the rings of Saturn.

That's, well, quite insulting, to use phrases like "thought he needed". I hope that you'll at least accept that I understand the mainstream view.

Also, you have the number of my degrees wrong. If you want to use "facts" about me to make a snide remark, please at least have the courtesy to check it out first.

Which is why, in my scenario, I specified the acceleration as 100m/s up to .5c in the initial reference frame. Yet he's confused and believes if we fly out into space that we'll never get to where we want to be because we'll curve away.

If you accelerate, SR says that the distance shortens in the direction of acceleration. It does not curve. GR says that space around matter is curved, thereby deflecting light beams, for example.

__________________
______________________________________________
“He who asks a question is a fool for five minutes; he who does not ask a question remains a fool forever”
Chinese proverb
"All you need in this life is ignorance and confidence - and then success is sure." - Mark Twain.

I'm still trying to tease out the problem that you think that you have identified. It appears to relate to your use of the word "now". Let's consider the following.

I am standing in a field 1 km away from a house. The house has been packed with explosives and detonated. At some time, t1, as measured on my watch, I visually observe the explosion. At some later time, t2, I hear the explosion.

When did the explosion occur?
Did the explosion happen at t1?
Did the explosion happen at t2?
Did the explosion happen twice, i.e. once at t1, and once at t2?

Or did the explosion happen at some time prior to t1?

Or, putting it another way, at t1 could I have said that "the explosion happened now"?
Or, at t2, could I have said that "the explosion happened now"?

Or maybe I kept my eyes closed, so I dont see the explosion at t1. Does that mean that the explosion didn't happen at t1? Perhaps I can change reality by closing my eyes?

Yes, I just brought the two observers, seperated by distance, to places where it is absolutely obvious, that 1. There is no and cannot be an 'alien in a spaceship' traveling at "c", either coming from A to B or B to A and 2. Where space cannot be contracting to 0 'instantaneously', OR any of the other ridiculous scenarios that have cropped up to make the distance from A to B = Zero.........the Singularity 0 to infinity, any way you cut it....

Saying/defining anything 'in light's own frame'/the Singularity........And I do mean anything......like light experiences 0 time, or light can travel from A to B any distance to infinity in 0 time, OR that 'space contracts' to 0 from A to B at ANY distance...............is all the same exact thing as trying to say what it happening at T=0 of the Big Bang OR defining anything at R=0 at the core of a Black Hole!!!!!!!!!!!!!!!!!!!!!!!!!

But that definition of "now" is not related to the normal usage of the term simultaneos in SR.

Exactly......that's the whole point........the simultaneity conventions of SR are meaningless.

I have shown numerous times that the halfway LS setting two observers clocks to 0, at the same time, one here in the Milky Way Earth Frame, and one in M31 scientists planet rest frame, is absolutely meaningless as relates to Anything Relativity is doing............Relativity cannot and does not do.......

Specified amounts of 'Light Travel Time' across specified distances, period!



And these actually say..............Relativity is NOT and cannot be used in the Local Neighborhood.

Which makes this statement absolutely "Fatally Flawed"

And Tim Thomspon agrees...

In addition, these three considerations, and especially the last and bolded one, show that 'Even In Principle', it is NOT possible to ever be able to consider this science!!!

__________________
RussT
________________________________
Everything is, as it should be, otherwise, it wouldn't be!

This is inapplicable to your SR example. It is true (under GR*) when deciding how far away a receding galaxy is (and to a much lesser extent, how far away a speeding train is). But for two objects that are at rest with each other, the distance between them is constant anyway, so there's no complication with time and the simultaneity of the measurement events at each end of the rule: a meter rule is always a meter long in it's own rest frame, that's one of the fundamental principles of relativity.

* Under SR I believe there is only one choice for a given observer

Surely that's taken out of context. It sounds like it might be talking about the rest frame of the photon. But that is irrelevant to the rest frame of the two observers who you say cannot meaningfully synchronize their clocks. And it's also irrelevant to the quote you say it fatally flaws. It takes light some time to get to the moon and back according to my watch. That is not logically contradicted by it taking no time at all according to the "light's own watch".

__________________
There are 10 types of people in the world. Those who understand ternary, those who don't, and those waiting for a bus.
If logic doesn't work, then surely it does.

NO, you have not shown it. You have asserted it, and then ignored posts that you find to be inconvenient. This is typical behaviour for cranks, so, if you are not one, and you wish to show that you are not, it may be better if you actually try addressing people's responses without wandering off on strange diversions.

Why did you bring in clock synchronisation, and argue about it, if you assert that it is irrelevant to your concept of "nowness"? This is an idea that you have come up with, and you seem to be whining that SR does not address it.

Guess what, it does not address my measure of "greatness" of sports cars, either, and this too says nothing about whether SR is correct or not.

If you want to discuss some new, esoteric idea, then please define your terms, and stick to one definition.

You have not even made clear yet what your point is, except to use vague new ideas, then say that SR does not prove them.

I do wonder why he is doing this. He uses a term that SR does not, has not defined it, yet complains that SR does not deal with it correctly.

RussT, your posts simply a a mish-mash of words put together in a way seemingly designed to confuse. Define what you mean by "now", and what it would mean for them to be synchronised, or not.

If you have defined your "nowness" in such a way that it has only a local meaning, then why are you involving SR in the discussion?

I also notice that after I asked bout your physics education, you asked for mine, received it, used it to be snide, but still refused to tell us yours. Please do so.

The definition of "now" is crucial in this discussion. Lightspeed is in fact the speed of the "now".

The definition of "now" in observational sciences is based on an endless regression of coupled observations that is required by a self-conscious observer. By its regressional nature this leads to effects as: the lightspeed limit of information/energy transfer, the concept of "time as an imaginary dimension of space moving at c, quanta of energy, QM waves and the uncertainty principle. It is a direct consequence of positioning ourselves as an observer in this universe. These facts are explained in this 1934 booklet: The Serial Universe. Very interesting read.