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### Re: Relativity?

Posted: Sun Oct 15, 2017 11:51 pm
uwot wrote: Sun Oct 15, 2017 6:03 pm
davidm wrote: Sun Oct 15, 2017 5:03 pm
ken wrote: Sun Oct 15, 2017 5:59 amDoes the distance to alpha centauri, in fact, actually become shorter, or just appears to become shorter for the person in the spacecraft?
It actually is shorter. Really and truly.
Wouldn't that demand an absolute measure of space?
and motionless starting and ending points

-Imp

### Re: Relativity?

Posted: Wed Oct 18, 2017 2:56 pm
uwot wrote: Sun Oct 15, 2017 8:44 am
ken wrote: Sun Oct 15, 2017 4:42 amIn 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?
I think the problem is that many people think that there is some objective time, according to which the question 'How long was there nothing, before the Big Bang happened?' is answerable. Maybe there is, but from a human perspective, every method we have of measuring 'time' is dependent on our counting events that happen to material objects. A year is roughly how long it takes the Earth to orbit the Sun. A month is roughly how long it takes the Moon to orbit the Earth. A day is how long it takes the Earth to spin on it's axis. At that point it all gets arbitrary, because you can divide a day up any old how you like. In the west, we happen to have adopted the model of the ancient Egyptians and Mesopotamians of dividing a day into 24 hours, dividing hours by 60 for minutes, and minutes again by 60, for seconds. For day to day purposes, 'the time' is just a convenient way to describe the position of the Earth, in relation to the Sun and the Moon.
For scientific purposes a second is defined as "as the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom" ( https://en.wikipedia.org/wiki/Second ) If you read the article, you will see all the stuff that has to be accounted for, including that the clock is at rest, because if it is moving, then the number of transitions will differ for the same fundamental reason that the pulses in Einstein's light clock change.
ken wrote: Sun Oct 15, 2017 4:42 amWhat I was asking was in relation to 'time' IF it WAS possible to travel at a certain speed, namely the speed of light.
The thing is, even if there is some stuff that is 'time', we have no method of measuring it directly; all we can do is count things happening and the frequency of things happening is subject to variations caused by, among other things, the speed at which it is moving.
I would suggest not be to concerned about trying to measure some thing that may or may not even be there. Better to see what IS actually there first, in My eye.

Also, I have not read the article yet but you talked about accounting for the clocks that are at rest. But are they at rest? Is the earth, itself, actually not moving and thus resting, or is it spinning and/or travelling, at some speed also?

### Re: Relativity?

Posted: Wed Oct 18, 2017 3:03 pm
uwot wrote: Sun Oct 15, 2017 9:43 am
ken wrote: Sun Oct 15, 2017 4:33 amFurther 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.
Well, it was a few pages back, but yes it has:
uwot wrote: Thu Oct 12, 2017 12:44 pmOK. Assume that the speed of light really is as fast as anything can go. Suppose you have a grandfather clock travelling at c. If, in the simplest example, the pendulum is swinging in the plane of movement, it could swing backwards, but to swing in the direction of motion, it would have to exceed the speed of light; in which case, you have to abandon the premise that c really is the speed limit.
I really do have to be absolutely precise. What about the clock in a phone? If the power source stays the same, then what would supposedly change that rate of change when traveling, and, and how exactly would 'the thing that supposedly changes the rate of change' actually be able to do it?

### Re: Relativity?

Posted: Wed Oct 18, 2017 3:12 pm
surreptitious57 wrote: Sun Oct 15, 2017 11:25 am
ken wrote:
how long does it take a human being to travel 4 light years travelling at the speed of light
A human being will take no time at all to travel anywhere if travelling at the speed of light

Nothing that travels at the speed of light experiences time. Regardless of the distance it travels. Photons have been observed travelling at the
speed of light all the way back to the Cosmic Microwave Background which occurred just 380 000 years after the Big Bang. But they can travel
from then to now in no time at all which is I3 billion years. They will carry on travelling in vacuum forever. As their lifespan is literally infinite
And they are the only physical entity known to have that capability. But even so they will never actually experience time during their lifespan
How do human beings supposedly "know" a big bang was about 13 billion years ago? Could it be because human beings measure these "distances" in light years, which is determined by the speed of light?

I have already gone over the fact that photons, as far as we know, do not experience any thing.

If a human being could travel to another planet 4 light years from instsntly, or what you call "no time at all", then if they traveled back to earth, at the same speed, are you saying they would arrive back also instantly and thus about 8 years behind every other human being on earth? If the answer is yes, then is that what human beings mean when they say "time travel"?

### Re: Relativity?

Posted: Wed Oct 18, 2017 3:18 pm
surreptitious57 wrote: Sun Oct 15, 2017 4:28 pm That depends on frame of reference. Anything travelling at the speed of light will not experience time
while an observer watching it sees it travelling through time. Time is therefore not absolute but varies
depending on speed and frame of reference and therefore does not pass at the same rate for everyone
This 'IT', every thing, is relative to the observer.

Also, My question was not asked solely I relation to any single observer. My question was in relation to what IS the time that takes?

This thread is about relativity, and, in My own way I want people to discover for themselves if "time" itself actually exists or not?

Is there actually a thing that a so called "time" thing could be measured relative to?

The answers are HERE right NOW, but how many are yet even able to to see them?

### Re: Relativity?

Posted: Wed Oct 18, 2017 3:39 pm
davidm wrote: Sun Oct 15, 2017 5:03 pm
ken wrote: Sun Oct 15, 2017 5:59 am
Is that an assumption or a known fact?
Known fact.
The sun revolves around the earth was once a known fact.

You seem to be under the impression that what you know as known and actual fact can NOT, and NEVER will, be changed?
davidm wrote: Sun Oct 15, 2017 5:03 pm
But does the actual trip take 2.12 years, or is that only what the person the spaceship observes?
It takes 2.12 years in his frame. Actual fact.
So to a person on earth how long does the actual trip take?

To a person on the planet that where the trip ends, how long does the trip take?

To a person on another planet, how long does the trip take?

The earth was flat was once an actual fact.
davidm wrote: Sun Oct 15, 2017 5:03 pm
Does the distance to alpha centauri, in fact, actually become shorter, or just appears to become shorter for the person in the spacecraft?
It actually is shorter. Really and truly.
SO, if a person takes that trip, then the people on earth will then say the distance to alpha centaur is now shorter so what we observed, thought, assumed, and/or believed was real and true before now is not. So, we better change all the literature in this regard to what is now really and truly the known fact. Is this right, from your perspective?
davidm wrote: Sun Oct 15, 2017 5:03 pm
What appeared to be the case would be proven right or wrong when they arrived on alpha centauri and looked back at earth. Then things would be brought back into their true perspective.
One hundred percent wrong.
So you are that advanced that even know what that person would see when they looked back? You say I am one hundred percent wrong that things would be brought back into perspective, after another perspective or point of view was looked from, so what is one hundred percent the correct, true, and right perspective that we ALL should be looking from and seeing? You really seem to believe that you Know the actual and true facts already?
davidm wrote: Sun Oct 15, 2017 5:03 pmThere is no 'true perspective' (technically, no preferred frame). That is the whole point of the theory.

It is obvious by now that you either cannot or will not grasp this. It's exactly like PauloL with evolution.
But I am NOT really stating any thing. I am asking questions. It is you, human beings, who are stating what is, supposedly, the true and right actual known facts.

I am just pointing out what you human beings do, in this day and age.

### Re: Relativity?

Posted: Wed Oct 18, 2017 3:43 pm
davidm wrote: Sun Oct 15, 2017 5:10 pm If Ken really wanted to learn about this, he could read a few books, take a class, or even use Google!

Did it ever occur to Ken that Albert Einstein asked, "what would it be like if a human could travel at the speed of light? What would he experience?" And of course Ken could find the answer to these questions with a little Googling, now couldn't he?

Of course, these gadankens by Einstein eventually showed him that humans cannot travel at light speed.

So today, to ask the question: "What would a human experience if he could travel at the speed of light?" has only the following answer:

If a human could travel at the speed of light, relativity theory would be wrong.

But it's not wrong.

So a human can't travel at light speed.
BUT I am NOT asking what a human being would experience...? That is what you, and some others, are reading into My question. This is because of the way the brain works. What I was mainly asking IS How long would the trip take?

### Re: Relativity?

Posted: Wed Oct 18, 2017 3:48 pm
davidm wrote: Sun Oct 15, 2017 5:30 pm
ken wrote: Sun Oct 15, 2017 6:04 am

Have they, if so, then how long does it take a human being to travel 4 light years traveling at the speed of light?
Just to humor you for a moment, let's say god made an exception for one human being to travel at light speed, while the theory of relativity otherwise completely holds.

The answer would be that from his perpspective in this miracle frame, the human would travel zero distance in zero time. How a human brain would function in zero distance at zero time is beyond me, though. Maybe another miracle from Jesus?
Just goes to show some human beings just can NOT stay open and focused on a very simple thought experiment using imagination.

It is a wonder that human beings on a whole have gotten as far as they have with some many of them behaving like this one here for example, which is what is holding them back from advancing much further.

### Re: Relativity?

Posted: Wed Oct 18, 2017 3:52 pm
thedoc wrote: Sun Oct 15, 2017 7:11 pm
ken wrote: Sun Oct 15, 2017 5:00 am 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?
If the Humans that have traveled to Alpha Centauri at near light speed could look back and see instantly, they would see the Earth at the current date, otherwise they would see it as it was in the past, based on the length of time it takes the light to get to Alpha Centauri or 4.37 years, and it would take them a bit longer than that to get there, depending on what fraction of the speed of light they were traveling at.
It appears that My questioning may have obtained three relatively completely different answers, if not at least two.

### Re: Relativity?

Posted: Wed Oct 18, 2017 3:54 pm
davidm wrote: Sun Oct 15, 2017 8:31 pm
uwot wrote: Sun Oct 15, 2017 6:03 pm
davidm wrote: Sun Oct 15, 2017 5:03 pm

It actually is shorter. Really and truly.
Wouldn't that demand an absolute measure of space?
It's actually, really true in his frame. In the earth frame, it's not true.
So, what is really and truly true?

### Re: Relativity?

Posted: Wed Oct 18, 2017 3:58 pm
davidm wrote: Sun Oct 15, 2017 5:10 pm, relativity theory would be wrong.
Is relativity theory a theory, or, an unambiguous fact that can not be disputed?

### Re: Relativity?

Posted: Wed Oct 18, 2017 4:14 pm
ken wrote: Wed Oct 18, 2017 2:56 pmI would suggest not be to concerned about trying to measure some thing that may or may not even be there. Better to see what IS actually there first, in My eye.
Thanks for the suggestion, but it is precisely what I am advocating, and in fact, the modus operandi of physics. What is actually there, is the phenomenon, which you can measure and generate mathematical models to describe. What you can never know, is whether the postulates of your model refer to anything real. But, what most lay people, and probably most physicists fail to understand, is that the 'truth' about reality has no impact on the efficacy of the models.
ken wrote: Wed Oct 18, 2017 2:56 pmAlso, I have not read the article yet but you talked about accounting for the clocks that are at rest.
Well, as a simple courtesy, I would recommend reading something before responding to it.
ken wrote: Wed Oct 18, 2017 2:56 pmBut are they at rest?
No; as you would know had you read the article. Clocks are only at rest relative to an observer in the same inertial frame, i.e. someone who is moving in the same way as the clock-you and your wristwatch/phone, for example.
ken wrote: Wed Oct 18, 2017 2:56 pmIs the earth, itself, actually not moving and thus resting, or is it spinning and/or travelling, at some speed also?
As Galileo (allegedly) said: 'And yet it moves.

### Re: Relativity?

Posted: Wed Oct 18, 2017 4:32 pm
ken wrote: Wed Oct 18, 2017 3:58 pm
davidm wrote: Sun Oct 15, 2017 5:10 pm, relativity theory would be wrong.
Is relativity theory a theory, or, an unambiguous fact that can not be disputed?
You have to understand the difference between the physics and the philosophy. The physics, ultimately, is the mathematical description of what can be seen to happen. If you want to dispute that, then you have to find something that doesn't conform with the maths. It would be a complete waste of your time trying to make an argument about what the universe 'should' do. It does what it does, and relativity describes it very well. If you want to argue for a reason 'why' the sums add up, that is up to you, but very few physicists give a monkey's.

### Re: Relativity?

Posted: Wed Oct 18, 2017 7:20 pm
ken wrote:
How do human beings supposedly know a big bang was about 13 billion years ago

If a human being could travel to another planet 4 light years from instantly or what you call no time at all then if they travelled back to earth
at the same speed are you saying they would arrive back also instantly and thus about 8 years behind every other human being on earth If the
answer is yes then is that what human beings mean when they say time travel
The red shift of galaxies and the Cosmic Microwave Background Radiation can be observed occurring just after the Big Bang. Red shift is caused by objects moving further away not only in distance but in time too. The Big Bang is still occurring because the Universe is still expanding and so it is not just an event that happened in the past but one that is also happening now

If ken travels in his spaceship at the speed of light to a planet four light years away and then travels straight back to Earth he will not have aged at all while everyone on Earth will have aged by eight years. If someone is travelling at the speed of light technically they cannot be engaging in time travel because they will not actually be experiencing any time. So time travel is more about travelling to locations in the past or the future

### Re: Relativity?

Posted: Wed Oct 18, 2017 7:51 pm
ken wrote: Wed Oct 18, 2017 3:58 pm
davidm wrote: Sun Oct 15, 2017 5:10 pm, relativity theory would be wrong.
Is relativity theory a theory, or, an unambiguous fact that can not be disputed?
Theories are not the same as facts.

Example: evolution is a fact. The theory of evolution describes and explains the facts, while enabling scientists to make predictions and retrodictions based on their model of the facts -- their theory.