Seeing things in their past? You are full of beans!

[Kangaroo Feathers]

Not trying to discredit what you are saying, because I do agree a ly is a unit of distance. I acknowledge, I don't know near what you guys do about this.

But couldn't you say in some sense, that it is a measurement of time for light? i.e. the time it takes light to go a certain distance.

For example, if light is 1ly away it takes 1 year to get here.
if it is 2ly away it takes 2 years to get here
if it is 1/2 ly away it takes 1/2 year to get here, etc.
It's the number in front that changes. When the number changes, I agree the distance has changed, but hasn't the time required for arrival changed also?

To me that sort of seems to be representing time (although it is only time for light) in some kind of a way.

Not in any practical fashion. Only if you think a mile is a unit of time based on how long it takes you to walk it.

 

[james blunt]

How much time does it take for an electromagnetic field to enter your eyes?

 

[TrueBeliever37]

Once again, time is relative. Look up the Lorentz transformations, or here let me do it for you:

Lorentz transformation - Wikipedia

As an object approaches the speed of light time for that object slows down, and distances decrease. At the speed of light there is no time and there is no distance. Our world appears to be Newtonian because we operate at a speed much less than the speed of light. It is a hard concept to wrap your mind around, but It has been extensively tested and found to be correct.

If at the speed of light there is no time or distance. My question for you is:

Why, in the name of common sense doesn't it appear to us instantly if it is say 4ly away? The answer is because it takes time, and has to cover some distance to get to us.

It is so obvious to see that time and distance are involved because it takes even longer if it is say 8ly away. The light was traveling at the same speed (the speed of light) in both scenarios. If no time or distance is involved why does the 2nd scenario take more time?

I think Sustainer is right about needing to use your own minds and not just relying on what scientific theory says. Sometimes they get it wrong. One reason the theory changes at times, is someone thinking outside the box, with an open mind, finds a way to refute or expand the existing theory.

 

[TrueBeliever37]

I would have you on my team any day of the week, you are truly open minded and objective .

p.s If I had a team lol

Thanks, I really appreciate the compliment.
I have to admit, I have been trying to help you, because it seemed like they were all teaming up against you and I thought you were correct in what you were saying.

I don't understand why they won't take you up on your challenges with the diagrams. (Unless they have, and I just missed their posts.)
If they are correct, they should have nothing to fear.

 

[james blunt]

Thanks, I really appreciate the compliment.
I have to admit, I have been trying to help you, because it seemed like they were all teaming up against you and I thought you were correct in what you were saying.

I don't understand why they won't take you up on your challenges with the diagrams. (Unless they have, and I just missed their posts.)
If they are correct, they should have nothing to fear.

They always fail to take me up on the challenges, ten years or so now , unchallenged. They preach Wiki more religious than religious preach religion. You show them where they are incorrect but they carry on repeating what you are showing is incorrect. Ironic really and thanks for the support.

 

[TrueBeliever37]

Not in any practical fashion. Only if you think a mile is a unit of time based on how long it takes you to walk it.

A light year is a distance, but it is a distance based on time. That is why it is referred to as a light year.
A meter or a mile is not based on time. There is a difference.

When I read the article that said the Sun was a little more than 8 light minutes away from the earth, guess what I knew immediately?
It wasn't the distance. It was a time. I knew that it was going to take a little more than 8 minutes for the light to get from the Sun to the earth.

If you told someone that light was 1/3 of a light year away, they wouldn't know the distance without calculating it. But they could probably just tell you that it would take 4 months for the light to get here. To me that is practical.

Pick another number - say 20ly away. What is the distance without calculation? Now tell me the time it would take the light to get here.

I am not saying it is not a distance. I am just saying that time is involved with the term.

 

[ecco]

Sustainer,

If I understand you correctly, the distance between two adjoined points is time divided by infinity. Is that correct?

loc(point A) - loc(point B) = T/∞

No , simply A + B = r1

But the change of space-time from point to point can be infinitely fast.

OK, now I understand you. The sum of the locations of two adjoined geometric points form a radius of 1 within which space-time moves infinitely fast.

That leads to another question; what does the "1' represent? Is it one meter or one light year or one something else?

 

[ecco]

Why, in the name of common sense

Common sense tells you the earth is flat.
Common sense tells you people would fall off the bottom of a sphere.
Common sense tells you light cannot be a particle and a wave.
Common sense tells you two particles cannot "communicate" instantly at any distance (even Einstein had his doubts).

Common sense is pretty worthless when it comes to many things, especially in science.

 

[Thermos aquaticus]

But couldn't you say in some sense, that it is a measurement of time for light?

It is a measurement for any object with a velocity. For example, a bullet travelling at 500 m/s would take 6E5 years to travel 1 ly. It just so happens that for photons in a vacuum the conversion factor is 1.

 

[sealchan]

Don't make me go and get my physics textbooks and start a lecture...Sustainer...get a used copy of Physics by Halliday and Resnick. Then after reading the relevant section and doing some of the problems at the end of the chapter try making a physics is non-sense post...you'll suddenly loose interest in the whole matter.

 

[Thermos aquaticus]

The article is interesting, but I can't wrap my head around some of the statements. They seem contradictory at times.

The easiest method is to put the numbers into the equations for time dilation.

Δt = the observer time, or two-position time (s)

Δt0 = the proper time, or one-position time (s)

v = velocity (m/s)

c = speed of light (3.0 x 10^8 m/s)

When you plug the speed of light into the equation for v you get a zero in the denominator. Therefore, anything moving at the speed of light does not experience time.

It said, Photons don't experience time or distance. Yet it also says Photons emitted might exist for hundreds of trillions of years. How is that not time?

That is time in our frame of reference, not the photon's frame of reference.

It said, Photons emitted from the surface of the Sun need to travel across the vacuum of space to reach our eyes. How is that not distance?

That is distance measured in our frame of reference, not the photon's frame of reference.

I also noticed in one article where it said The Sun is more than 8 light minutes away. That sounds like a time reference as well as distance to me.

It is only a measurement of time when the velocity of the object is known.

 

[Thermos aquaticus]

How much time does it take for an electromagnetic field to enter your eyes?

Depends on the distance from the point of origin and the medium the photon is passing through.

 

[Subduction Zone]

If at the speed of light there is no time or distance. My question for you is:

Why, in the name of common sense doesn't it appear to us instantly if it is say 4ly away? The answer is because it takes time, and has to cover some distance to get to us.

It is so obvious to see that time and distance are involved because it takes even longer if it is say 8ly away. The light was traveling at the same speed (the speed of light) in both scenarios. If no time or distance is involved why does the 2nd scenario take more time?

I think Sustainer is right about needing to use your own minds and not just relying on what scientific theory says. Sometimes they get it wrong. One reason the theory changes at times, is someone thinking outside the box, with an open mind, finds a way to refute or expand the existing theory.

It takes time for us. It does not take time for the particle. The date the time passes depends upon the relative velocity of the object in motion.

I see you hat others have tried to explain this as well. Tell me if you still need more. It is a difficult concept to grasp.

 

[sealchan]

They always fail to take me up on the challenges, ten years or so now , unchallenged. They preach Wiki more religious than religious preach religion. You show them where they are incorrect but they carry on repeating what you are showing is incorrect. Ironic really and thanks for the support.

Have we covered time dilation and length contraction yet? Anyone?

From the point of view of light, if one could ride on a particle of light no time would pass. For anyone moving at any speed, light always appears to be moving at the speed of light. This contradicts our common sense understanding and even our Newtonian understanding of speed and relative speed. Einstein knew and understood this but he looked past it long enough to get at an answer that explains the phenomenon he had to explain (like the Michelson-Morley experiment).

The common sense understandings are not wrong, they are just completely practical approximations at our scale of everyday experience for something which is subtly different in the more complete way of understanding things. The new mathematical equations which take Einstein's relativity theory into consideration work just as well for common sense (at the scale of common sense) as they do for other phenomenon that the old equations don't work for.

So Sustainer why don't you at least read up on the Michelson-Morley experiment (if you haven't already) and explain its results based on a common sense understanding of observed velocity?

 

[Thermos aquaticus]

A light year is a distance, but it is a distance based on time.

A light year is based on a reference, that being the speed of light and the orbital time of Earth. We could also use parsecs for our distance which is based on the parallax of stars at the extreme ends of Earth's orbit. It is no different than the kilogram which is based on a reference. The light year is an arbitrary distance that we have chosen because we can define it with well known physical constants.

A meter or a mile is not based on time. There is a difference.

The meter can be defined using the speed of light.

"The meter is the length of the path travelled by light in vacuum during a time interval of 1/299 792 458 of a second."
Base unit definitions: Meter

And that is from the organization that has been put in charge of defining metric units.

When I read the article that said the Sun was a little more than 8 light minutes away from the earth, guess what I knew immediately?

It wasn't the distance. It was a time. I knew that it was going to take a little more than 8 minutes for the light to get from the Sun to the earth.

If you tell someone that you are 30 minutes away, what does that mean?

 

[Subduction Zone]

If you tell someone that you are 30 minutes away, what does that mean?

That traffic was rather light that day?

 

[ecco]

A light year is a distance, but it is a distance based on time. That is why it is referred to as a light year.
A meter or a mile is not based on time. There is a difference.
I am not saying it is not a distance. I am just saying that time is involved with the term.

What is a meter based on?

meter. The basic unit of length in the metric system; it was originally planned so that the circumference of the Earth would be measured at about forty million meters. A meter is 39.37 inches.

Today, the meter is defined to be the distance light travels in 1 / 299,792,458 seconds.

The mile is an English unit of length of linear measure equal to 5,280 feet, or 1,760 yards, and standardised as exactly 1,609.344 metres​

So, in the interests of greater accuracy, the meter is a distance based on the speed of light. And the mile is also a distance based on the speed of light. Just as a lightyear is a distance based on the speed of light.


Astronomers needed some "measurement" to calculate distances to distant objects, miles was way too small. One method they invented was a calculation based on the distance light would travel in the time it takes the earth to make one solar orbit.

We know how fast light travels: 299 792 458 m / s.
We know how many seconds it takes the earth to make on solar orbit: approximately 31,556,736
Multiply one by the other and you get a distance of about 9.46 trillion km.

Another method they invented is called a parsec.

 

[TrueBeliever37]

Common sense tells you the earth is flat.
Common sense tells you people would fall off the bottom of a sphere.
Common sense tells you light cannot be a particle and a wave.
Common sense tells you two particles cannot "communicate" instantly at any distance (even Einstein had his doubts).

Common sense is pretty worthless when it comes to many things, especially in science.

Common sense is important also, no wonder you don't understand.

 

[TrueBeliever37]

It takes time for us. It does not take time for the particle. The date the time passes depends upon the relative velocity of the object in motion.

I see you hat others have tried to explain this as well. Tell me if you still need more. It is a difficult concept to grasp.

If it doesn't take time for the particle, then why is it not here instantaneously? Or are you saying it is?

Why does it take 4 years of our time to get here from 4ly away?

Of course but the date I cross the finish line in a race depends on my velocity also.

 

[Thermos aquaticus]

Common sense is important also, no wonder you don't understand.

"Common sense is the collection of prejudices acquired by age eighteen."--Albert Einstein