Relativity?

How does science work? And what's all this about quantum mechanics?

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davidm
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Re: Relativity?

Post by davidm » Sat Oct 14, 2017 6:37 pm

Just to note, thought experiments are fine but usually they are idealizations not realizable in practice. It’s amusing to note that in the case of the light clock I have imagined in which it takes one second for the photon fired from the top to hit the bottom and return to the top, it would follow that the top of the clock and the bottom would have to be separated by a distance of about 93,000 miles. :lol: I don’t think anyone will be building a light clock 93,000 miles tall anytime soon, still less fitting it onto any conceivable moving conveyance. :lol: And of course the conveyance itself would have to travel at a relativistic velocity for the effects described above to be noticeable.

uwot
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Re: Relativity?

Post by uwot » Sat Oct 14, 2017 6:54 pm

davidm wrote:
Sat Oct 14, 2017 6:37 pm
Just to note, thought experiments are fine but usually they are idealizations not realizable in practice.
Quite. But the basic premise of special relativity, constant velocity, is itself an idealisation, that has no basis in reality.

davidm
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Re: Relativity?

Post by davidm » Sat Oct 14, 2017 7:05 pm

uwot wrote:
Sat Oct 14, 2017 6:54 pm
davidm wrote:
Sat Oct 14, 2017 6:37 pm
Just to note, thought experiments are fine but usually they are idealizations not realizable in practice.
Quite. But the basic premise of special relativity, constant velocity, is itself an idealisation, that has no basis in reality.
Right but SR is subsumed under GR.

ken
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Re: Relativity?

Post by ken » Sat Oct 14, 2017 11:27 pm

thedoc wrote:
Sat Oct 14, 2017 1:25 pm
ken wrote:
Sat Oct 14, 2017 12:33 pm
We were talking about photon exchange, you said at the speed of light photons can not exchange. I pointed out that photons traverse the Universe in ALL directions and thus are always exchanging. The exchange of photons is the sort of collisions, and obviously would also be a part of the process of interactions that causes ALL atoms to come together into existence as coherent bodies, including even the thinking human bodies.
I think the point is that usually photon exchange happens between the photons and some physical body or a mass. Physical Bodies don't travel at the speed of light, first of all there is not enough energy to get them to that speed and second if they did achieve the speed of light they would not exist as a physical body, this is all according to the theory of relativity. Photons do not have mass, (as far as we know) and cannot have an exchange with each other.
Although I also see all of that is good and true I did make it quite clear, from the outset, that I KNOW the stated fact that physical bodies do not and can not travel at the speed of light. I just asked people to imagine IF it was possible, and then proceeded to asked some clarifying questions in regards to that.

ken
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Re: Relativity?

Post by ken » Sat Oct 14, 2017 11:50 pm

davidm wrote:
Sat Oct 14, 2017 4:45 pm
ken wrote:
Sat Oct 14, 2017 6:25 am
A human being with a clock is traveling in a ufo at the closest speed to light speed as possible, let us say it is 99% of the speed of light, from earth to a planet 3 light years away. How long would the trip take?
I dunno specifically, I don’t feel like working out the math right now, but it’s easy enough to do. I think it should take about 70 days, as judged by the guy on the UFO, who would see his clock ticking normally just as it did on earth. As judged by an earth observer, the trip would take three years.
Back to the question that I actually asked, How long would the trip take? (You do not have to be precise, I would just like the approximate answer).

When the ufo got to the planet it would then have to slow (break inertial frame) turn around and go back to earth. Another seventy days as judged by rocket man, another three years as judged by earth guy. These are all idealizations, ignoring the time it would take to accelerate to 99 percent light speed, etc. But it's fine as a thought experiment.
davidm wrote:
Sat Oct 14, 2017 4:45 pm
When rocket guy and earth guy reunite in earth frame and compare clocks, rocket man will discover that he has aged about 140 days while earth guy has aged about six years.
Now, WHY would it take the human being in the ufo supposedly FAR less "time" than say light would take to travel the exact same distance, especially when light is travelling faster?

When, and if, these questions are answered, then we can proceed further with the thought experiment. Also, does any one have an answer as to why you, human beings, can do a thought experiment when discussing traveling anywhere between zero and just short of the speed of light, but it seems near impossible to get you human beings to do a thought experiment in regards to traveling at the speed of light? It is like their brains just completely block them from even being able to fathom the idea, let alone being able to see and discuss it?

ken
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Re: Relativity?

Post by ken » Sun Oct 15, 2017 12:08 am

davidm wrote:
Sat Oct 14, 2017 4:58 pm
ken wrote:
Sat Oct 14, 2017 6:25 am
And, what happens to the clock, would it slow down compared to when it was on earth, or would it keep moving at the same rate as it would on earth, or some thing else?
If you at least understood Galilean relativity, much less special relativity, you would already have your answer.
Are you unable to answer the question, or do you just prefer not to answer because of the following clarifying questions that I will then ask? Are you afraid that somewhere down this track you will be unable to answer correctly, and of the ramifications to you that will eventually follow? You are trying to allude to the fact that it was a very simple and easy question to answer, SO, what stopped you from answering that question?

What I observe as an answer NOW does NOT matter. What I am doing here is an experiment. I am learning how to better express how you, human beings, can find the actual truth of things. What I want to know is what others actually know and understand. The outcome of this experiment is what I need to express My Story, better.

By the way what human beings see as the answer, at certain times in their, individual and collective, lifes is NOT always even close to the truth. This has been proven countless times already. But until you provide Me with your answers, I can not show and prove this fact, for now.

ken
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Re: Relativity?

Post by ken » Sun Oct 15, 2017 12:14 am

davidm wrote:
Sat Oct 14, 2017 5:00 pm
ken wrote:
Sat Oct 14, 2017 6:25 am
Also, all of what you said here is a good attempt to divert away from what I was asking and trying to get to, but if you think I am just another puppet that will only follow that what has been and is continually taught, then you have another thing coming.
Bwa-hah-hah! Yes, I am the evil puppet master! :twisted:
Well you appear to be the type of person, and correct Me if I am wrong her, who internally laughs at others and tries to ridicule those who do NOT have and see the exact same answers you have. Is this right or wrong?

You even just tried to do this ridiculing in the quote above this reply.

Have you even considered that the answers you are giving here might just not be as accurate and correct as you believe they are?

davidm
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Re: Relativity?

Post by davidm » Sun Oct 15, 2017 1:09 am

ken wrote:
Sat Oct 14, 2017 11:50 pm
Back to the question that I actually asked, How long would the trip take? (You do not have to be precise, I would just like the approximate answer).
I effing answered the question you actually asked! Can you not read?

The one-way trip would take 70 days, give or take, from the point of view of the guy on the UFO. The one-way trip would take just over three years, from the point of view of people on earth.

What part of this do you not grasp? Please elaborate!

Christ, this is exactly like dealing with PauloL in the evolution thread!

davidm
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Re: Relativity?

Post by davidm » Sun Oct 15, 2017 1:55 am

ken wrote:
Sun Oct 15, 2017 12:08 am

Are you unable to answer the question, or do you just prefer not to answer because of the following clarifying questions that I will then ask?
I HAVE answered these questions, dumb fuck. So has uwot.

Learn to read!

davidm
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Re: Relativity?

Post by davidm » Sun Oct 15, 2017 2:28 am

ken wrote:
Sat Oct 14, 2017 11:50 pm
Now, WHY would it take the human being in the ufo supposedly FAR less "time" than say light would take to travel the exact same distance, especially when light is travelling faster?
Read this: Ten Minutes to Alpha Cenatauri? (You won’t read it, of course.)

Hint: Length contraction. (Which I discussed, albeit briefly, upthread. Did you gloss over that too in your frantic impatience to be the internet rando who overturns standard science?)

From the above link:
To see how this works, let us suppose our spaceship heads to Alpha Centauri at 90% of the speed of light.  According to the Earth-bound observer, the trip should take 4.86 years.  According to the person on the spaceship, however, the trip takes only 2.12 years!

This is quite surprising — according to our argument, it seems that the spaceship pilot can reach Alpha Centauri in less time than it would take light.  At first glance, it would seem our spaceship is traveling faster than light, since it travels 4.37 light-years in 2.12 years.  However, what in fact happens is that the distance to Alpha Centauri becomes shorter for the person in the spacecraft.
Italicized by the author, not me.

davidm
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Re: Relativity?

Post by davidm » Sun Oct 15, 2017 2:51 am

ken wrote:
Sat Oct 14, 2017 11:50 pm
Also, does any one have an answer as to why you, human beings, can do a thought experiment when discussing traveling anywhere between zero and just short of the speed of light, but it seems near impossible to get you human beings to do a thought experiment in regards to traveling at the speed of light? It is like their brains just completely block them from even being able to fathom the idea, let alone being able to see and discuss it?
Actually, in this very thread, people HAVE imagined humans traveling at the speed of light! I ask again, Can you not properly read?

However, such speculations are otiose, because humans CANNOT travel at the speed of light.

But if (for example) atoms could, as uwot has postulated for the hell of it, and if you understood the principle of the light clock, you would understand his point that there could be no photon exchanges between atoms moving at c. Of course you don't understand. As Trump would say, Sad!

davidm
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Re: Relativity?

Post by davidm » Sun Oct 15, 2017 3:43 am

For a spaceship traveling at 90 percent the speed of light toward Alpha Cetauri:

Earth observer: Alpha Centauri is 4.37 light years away.

Spaceship observer: Alpha Centauri is 1.90 light years away!

Image

Who’s right?

They’re both right!

ken
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Re: Relativity?

Post by ken » Sun Oct 15, 2017 4:33 am

davidm wrote:
Sat Oct 14, 2017 5:52 pm
ken wrote:
Sat Oct 14, 2017 6:25 am
Now, If a "normal" clock, and NOT a light clock, is traveling at closest as possible to the speed of light, then does it slow down or does it tick away at the human made rate that it did prior to taking the trip? Whatever your answer is, can you then explain how this is possible?
But I HAVE explained. Maybe you don’t pay attention? Perhaps you should write less and read more?
Maybe I have been paying attention? Just maybe some one else has not been paying as much attention to what is really going on here?

Further to this you explained how a LIGHT clock reacts to traveling at speed, relative to a light clock on earth, right? My question here is in regards to a "normal" clock, which has NOT yet been answered nor explained.
davidm wrote:
Sat Oct 14, 2017 5:52 pm
There is no difference between a “normal” clock and a light clock; they both do the same exact thing — tell time — and they can be synchronized with each other.
So, they both give a pre-determined, by human beings, measurement of what is loosely called "time"?

They both might do the same thing, and that is give measurements, but do they both work the same way? That is do they both, what you call "tell time" through the exact same mechanisms?
davidm wrote:
Sat Oct 14, 2017 5:52 pm
The reason the light clock is used in these examples is because it shows WHY time slows down, which is not evident from a regular tick-tock clock.
Are you suggesting that the thought or belief that "time slows down" was prior to finding some thing that will show WHY this happens?

Also, if it is not evident from a regular tick-tock clock that "time" slows down, then are you saying and/or implying that a regular tick-tock clock will just keep on ticking and tocking how it does no matter how fast it is going? If so, then fine. If not, then you will really need to make use of your words and/or express your words better.

You are saying here that "time slows down". What does "time" mean, to you?

If, and when, people go over My previous writings THEN they will see WHY I say, "Time only appears to slow down, to some", which is in strike contrast to what you are saying here. "How could "time" slow down and/or stop?"

To Me, obviously different people see things differently, and the reason for this, by the way, is also obvious, but what appears to be "time", to some, is partly the reason of why to them "time" also appears to slow down and/or stop. But to state, "Time slows down, and/or stops" is a pretty big absolute statement, which I am having trouble with getting people to explain further how this could actually happen. One reason they can not is because what APPEARS to be the case is NOT really the truth of the matter.

What is going on here is like how previously to some people it APPEARED as though the sun revolves the earth. That is what they viewed, and so they then believed that to be the truth of the matter. But the truth was that was not the case, but they were just not ready to see the truth yet.
davidm wrote:
Sat Oct 14, 2017 5:52 pm
Here is how the light clock shows WHY time slows down in a moving frame relative to an at-rest frame (though I’ve already explained this):
AND, I have ALREADY explained that that is an extremely very simple and very easy thing to understand. HOWEVER, what the light clock is showing may just be NOT what the actual truth IS. What you do not seem to be understanding is the actual words you a using to explain things, like, for example, what you have just written, and continue to write, these do not make sense to Me. To Me, what you are trying to explain is like trying to explain that the sun revolves around the earth, when I KNOW this is NOT true, and so you are using every conceivable thing you can find to justify your position.

A light clock does NOT show WHY "time" slows down. A light clock was devised and used as example to show what APPEARED to be the truth, previously. People perceived some thing to be true already and then used whatever they could for confirmation bias, for their already held views and/or beliefs.

To Me, a light clock does NOT show WHY "time" slows down. What a light clock shows Me is WHY it appears as though "time" slows down.
davidm wrote:
Sat Oct 14, 2017 5:52 pm
1. The speed of light is invariant in all inertial frames. Everyone, regardless of their frame, measures the velocity of light as c in a vacuum.
So far, generally true.
davidm wrote:
Sat Oct 14, 2017 5:52 pm
2. This means that in a frame moving relative to a rest frame,
Where do you think this "rest" frame is, or could actually be?
davidm wrote:
Sat Oct 14, 2017 5:52 pm
a moving frame in which a light clock is operating, the speed of light will not ADD the velocity of the moving frame to its own velocity, as stuff normally does. If it did add the velocity, light would be traveling faster than light, which is not possible.
I will let this be.

davidm wrote:
Sat Oct 14, 2017 5:52 pm
3. The light clock can be set up just as a normal clock, in synchrony to depict the passing of one second: A photon is fired from the top of the clock to the bottom; there it rebounds to the top. When the photon reaches the top, it is in synchrony with a normal tick-tock clock, such that: At the end of the first round trip of the photon in the light clock, one second will have ticked off on a regular tick-tock clock. So each round trip of the photo represents one second of elapsed time. Follow?
I have explained this was all very easy to understand a few posts back already.

Maybe you were not paying attention, or just did not read it?
davidm wrote:
Sat Oct 14, 2017 5:52 pm
4. Now we imagine there is also a light clock in the rest frame.
Okay, but this is where the experiment and/or example partly starts to fail. But carry on.
davidm wrote:
Sat Oct 14, 2017 5:52 pm
5. But now because the light clock in the moving frame is in a frame that is in motion with respect to an at-rest frame, its photon must traverse a longer path to make one round trip, than does the photon in the at-rest frame! (This is depicted in the animation you watched.) Again, this has to happen, because c is invariant as measured from all frames, so the photon will not ADD the velocity of the moving frame to is own velocity.

Conclusion: The moving-frame light clock is “ticking” slower than the at-rest light clock, and they are now out of synchrony. Time is passing more slowly in the moving frame relative to the at-rest frame. (The person on the moving frame judges his clock to be ticking normally, just as it did in the rest frame. See: Galilean relativity.)

Hope this helps. (Yah, right!)
Is it an actual and absolute fact that 'time is passing more slowly' in the moving frame relative to the so called at-rest frame?

What you are trying to say is ALL very obvious and like I said extremely easy to understand. The moving-frame LIGHT CLOCK 'ticks' slower than the on-earth LIGHT CLOCK because the former clock is moving faster than the latter clock and it would obviously take the bouncing light from the LIGHT clock to bounce back and forth because the bouncing light takes longer to return on a moving-frame. Do you understand, Yes I understand ALL of that?

What you and others do NOT seem to have taken into account is if, in the same moving-frame reference place, BOTH the light clock and the regular tick-tock clock are alongside each other, then both clocks could be out of synchronization with each other just as much and even to the exact same extent as the light clock on the so called "at rest-frame" reference place is out of synchronization with the moving light clock? (This is clumsily written but will get better soon enough).

Anyhow, if the moving at the same speed regular tick-tock clock and the light clock are out of sync AFTER they where synchronized BEFORE they started moving, then this is because the two clocks work in obviously two different ways. One clock (the light clock) is depended upon light, and thus works at different rates of change because the rate of change is depended solely upon the speed it is traveling, while the other clock (regular tick-tock clock) is depended upon the "hands" ticking, which is not affected by speed, and thus works at the exact same rate of change no matter how fast it is going, just as long as the power source stays the same. Thus, the reason WHY a trip takes the exact same amount of, what is generally called, "time". Obviously this is RELATIVE to the speed at which the vehicle is traveling and to the distance it has to go.

And, the "time" it takes to travel a certain distance and how far the actual distances are can be uniformly measured because of that tool, generally referred to as the tick-tock clock, which human beings devised and constructed so they could breakdown change into measured increments. Without this measuring tool the one and only continual event could not as easily be separated into seemingly different and separate events, which we perceive and have become accustomed to now, nor could that one event be broken down into seemingly different and separate compartments of "space" and "time". Without the devise labeled the tick-tock clock, how could measurements be made in "space" and in "time"? But I am moving ahead to quick now now, and just wait to see how much of what I have been saying is understood.

ken
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Joined: Mon May 09, 2016 4:14 am

Re: Relativity?

Post by ken » Sun Oct 15, 2017 4:42 am

uwot wrote:
Sat Oct 14, 2017 6:37 pm
ken wrote:
Sat Oct 14, 2017 12:33 pm
We were talking about photon exchange, you said at the speed of light photons can not exchange. I pointed out that photons traverse the Universe in ALL directions and thus are always exchanging.
Well, the 'relationship' analogy didn't work. Perhaps 'exchange' means something completely different to you and I. But what I mean by it, is that one of a pair of atoms can emit a photon, which is absorbed by the other. At some future point, the second atom can emit a photon, which is absorbed by the first. It is this 'exchange' of photons that bonds the pair, and makes them a unit; it is literally what sticks them together (gluons do the same job for quarks, and get their name from glue.). Multiply that by several gazillion, and you have a macroscopic object. It is because the atoms that make the object can exchange photons, that the object is an object. The photons that make up Sun or starlight, were emitted by atoms that are so remote from the atoms in your retina, that the chance of the atom in your retina that absorbed a photon from a star, emitting a photon that is absorbed by the same atom in the star that emitted the first photon, ie, the two atoms exchange photons, is frankly zero.
At the speed of light, two atoms cannot 'exchange' photons, in the above sense.
In regards to if a physical body can exist at the speed of light, I KNOW that is it said to be IMPOSSIBLE, and from what you have said here has made Me realize much more about WHY it is said to be IMPOSSIBLE. It was very informative, makes a lot of sense, and very easy to understand, so I thank you a lot for that. BUT I was NOT and NEVER was asking about any thing in relation to a human being being able to travel at the speed of light. What I WAS asking and still am is IF a human being could possibly travel at the speed of light, what then would happen in relation to the time is takes to travel a certain distance? What I was asking was in relation to 'time' IF it WAS possible to travel at a certain speed, namely the speed of light.

ken
Posts: 2075
Joined: Mon May 09, 2016 4:14 am

Re: Relativity?

Post by ken » Sun Oct 15, 2017 5:00 am

davidm wrote:
Sun Oct 15, 2017 1:09 am
ken wrote:
Sat Oct 14, 2017 11:50 pm
Back to the question that I actually asked, How long would the trip take? (You do not have to be precise, I would just like the approximate answer).
I effing answered the question you actually asked! Can you not read?

The one-way trip would take 70 days, give or take, from the point of view of the guy on the UFO. The one-way trip would take just over three years, from the point of view of people on earth.

What part of this do you not grasp? Please elaborate!

Christ, this is exactly like dealing with PauloL in the evolution thread!
You seem to be missing the whole point of what I am writing in this relativity thread.

My question was "How long would the trip take?" I did NOT ask how long, to different people, would they THINK nor would the trip take?

The question is, how long would the actual trip take?

How can one trip take two different lengths of "time"?

Obviously there can be different perspectives of the length the trip takes, coming from different observers, who have different advantage points, and/or differing points of views, but surely there is only one correct answer of how long the trip actually took.

Even you said the trip would take 70 days from the human being doing the traveling. Lets us say that that human being has one eight hours sleep a day, a 'day' being 24 hours tick-tock clock on earth, and has three meals a day, so, to you, does that mean that that human being would have 70 times eight hour sleep and 210 meals? And, to you, while the people on earth would continue on for just over 3 years in the exact same "time" period?

Also, when the human being in the ufo land on the other planet and look back to earth, what would the date be that that human being was seeing on earth, and, what would the actual date be on earth?

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