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

[Thermos aquaticus]

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

Because we, as the observer, are not travelling at the speed of light. Time ticks by at different rates at different velocities. Time will measurably tick by faster in a jet liner at 30k feet than it does on the surface of the Earth, as another example. The clocks on GPS satellites have to be constantly adjusted because time is ticking by faster for the satellites than clocks here on Earth.

 

[sealchan]

Because we, as the observer, are not travelling at the speed of light. Time ticks by at different rates at different velocities. Time will measurably tick by faster in a jet liner at 30k feet than it does on the surface of the Earth, as another example. The clocks on GPS satellites have to be constantly adjusted because time is ticking by faster for the satellites than clocks here on Earth.

Yes, this is the crux of Einstein's special relativity theory...that the laws of physics hold for each person in their own inertial frame of reference but to make the laws hold for two different inertial frames of reference we have to add some math...

 

[Thermos aquaticus]

Yes, this is the crux of Einstein's special relativity theory...that the laws of physics hold for each person in their own inertial frame of reference but to make the laws hold for two different inertial frames of reference we have to add some math...

The one law of physics that does stay the same, ironically, is the speed of light. Once that is established you inevitably end up with time and length being measured differently between frames of reference.

Thought experiments for time dilation:
schoolphysics ::Welcome::

 

[TrueBeliever37]

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.



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.



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

If I tell someone I am 5 miles ( a distance ) away, what does that mean? It is purely a distance, and you have to perform mathematics on it using velocity to determine the time of arrival.

Yet when you tell me light is 4ly ( a distance) away, I don't have to do any mathmatics, and I know it would be here in 4 years. How am I able to do that if time (for light) is not already included in the term?

You are saying a light year is a distance only and not a time. From a purely technical definition I agree it is a distance. But it is also an expression that gives time for light. A time is built into it.

If it is not a term with time included, then why when someone tells me the sun is a little more than 8lm from the earth, do I know that it takes the light a little more than 8 minutes to get here?

 

[BilliardsBall]

So show the fish the water and its properties. We do the same with the air that is all around us, after all.

What does it even mean to say 'God is in us'? Which organ?

You cannot show fish the water because you have an inability to communicate with them on a level they understand/accept.

Kind of like skeptics.

 

[BilliardsBall]

So once again you can't justify your claim have to resort to hyperbole.



FYI, fish have a better eyesight than humans, particularly, a much wider frequency range, and still no god..

One cannot "tell a fish" about water anymore than certain skeptics can be told anything about the God who cares for them.

 

[Polymath257]

You cannot show fish the water because you have an inability to communicate with them on a level they understand/accept.

Kind of like skeptics.

I see, so non-skeptics have some magical abilities skeptics do not? Care to elucidate them and explain why these abilities are reliable?

 

[Thermos aquaticus]

If I tell someone I am 5 miles ( a distance ) away, what does that mean? It is purely a distance, and you have to perform mathematics on it using velocity to determine the time of arrival.

What does a "mile" mean? As stated earlier, the distance of a mile is based on the speed of light.

Yet when you tell me light is 4ly ( a distance) away, I don't have to do any mathmatics, and I know it would be here in 4 years. How am I able to do that if time (for light) is not already included in the term?

Time is included in when you ask how long it takes light to travel 4 ly. Light can only travel one speed in a vacuum, and that is 3E8 m/s. Notice that the speed has time in it. You insert time into the statement when you ask how long it takes light to travel that distance. If you ask how long it takes a bullet fired at 500 m/s to cover 4 ly the time changes.

You are saying a light year is a distance only and not a time.

Correct, since time will depend on velocity. Time is introduced by the velocity of the object.

. But it is also an expression that gives time for light. A time is built into it.

It gives a different time for different velocities and different objects.

If it is not a term with time included, then why when someone tells me the sun is a little more than 8lm from the earth, do I know that it takes the light a little more than 8 minutes to get here?

If I released a snail near the Sun which moved at 1 mm/s, would it take 8 minutes for the snail to reach the Earth?

 

[ChristineM]

One cannot "tell a fish" about water anymore than certain skeptics can be told anything about the God who cares for them.

Show me a fish with a grasp of human language and im sure one could communicate the properties of water to it. Until then i still consider your hyperbole based on a strawman (or strawfish)

And you can tell me much about your belief in god, (as you do). Its when i question your claims and ask you you provide evidence that your arguments fail, just like this one.

 

[Polymath257]

One cannot "tell a fish" about water anymore than certain skeptics can be told anything about the God who cares for them.

A fish that could speak and reason could be told about the water and it could be demonstrated to such a fish.

Non-skeptics tell skeptics about deities but can't actually demonstrate such things exist.

 

[TrueBeliever37]

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.



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



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



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

I guess we will just have to disagree, because if time is going by in my world, then time is going by.

If something moving at the speed of light does not experience time, then it should reach it's destination instantaneously.

Just by definition if something is moving at any speed including the speed of light - it is covering a certain distance in a certain amount of time.

 

[Polymath257]

I guess we will just have to disagree, because if time is going by in my world, then time is going by.

If something moving at the speed of light does not experience time, then it should reach it's destination instantaneously.

And from the frame of reference of the light, it does.

 

[ChristineM]

I guess we will just have to disagree, because if time is going by in my world, then time is going by.

If something moving at the speed of light does not experience time, then it should reach it's destination instantaneously.

Put your hand on a hot stove for a minute and it seems like an hour. Sit with a pretty girl for an hour, and it seems like a minute.
Albert Einstein

Time is relative

Light does not travel instantaneously, outside of vacuum It is also variable.

 

[Kangaroo Feathers]

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.

No one's denying time is involved with the term. It's still a measure of distance, not time, however. The time fomponent has already been measured, i.e. 1 earth year. To turn your reasoning around, can you tell how long it would take light to traverse a trillion kilometers without doing a calculation?

 

[Kangaroo Feathers]

Put your hand on a hot stove for a minute and it seems like an hour. Sit with a pretty girl for an hour, and it seems like a minute.
Albert Einstein

Time is relative

Light does not travel instantaneously, outside of vacuum It is also variable.

LiGht does not travel instantaneously to an outside observer. From the perspective of the light, it does. If you could somehow ride a photon traveling at C, you would experience traveling through every point in the universe simultaneously.

 

[ChristineM]

LiGht does not travel instantaneously to an outside observer. From the perspective of the light, it does. If you could somehow ride a photon traveling at C, you would experience traveling through every point in the universe simultaneously.

However we are not light surfing photons, hence relative

 

[TrueBeliever37]

What does a "mile" mean? As stated earlier, the distance of a mile is based on the speed of light.



Time is included in when you ask how long it takes light to travel 4 ly. Light can only travel one speed in a vacuum, and that is 3E8 m/s. Notice that the speed has time in it. You insert time into the statement when you ask how long it takes light to travel that distance. If you ask how long it takes a bullet fired at 500 m/s to cover 4 ly the time changes.



Correct, since time will depend on velocity. Time is introduced by the velocity of the object.



It gives a different time for different velocities and different objects.



If I released a snail near the Sun which moved at 1 mm/s, would it take 8 minutes for the snail to reach the Earth?

No, but I wasn't saying it was the time for a snail. I have been saying it was time for light or something moving at the speed of light. I have already agreed that a light year is a distance. I just think that the term has time (as regards light) built into it.

But if I understand correctly, I think you are saying time is not introduced by light, which has a velocity. Yet, above you say time depends on velocity.
So if light has a velocity, how is time not experienced?

What does the speed of light even mean, if not to say that it covers a certain distance in a certain amount of time?

 

[Thermos aquaticus]

I guess we will just have to disagree, because if time is going by in my world, then time is going by.

For you, time is moving by. Time ticks by at different rates at different velocities. This was confirmed by experiments:

Hafele–Keating experiment - Wikipedia

If something moving at the speed of light does not experience time, then it should reach it's destination instantaneously.

From the point of view of the photon, it does.

 

[Subduction Zone]

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.

Once again, you are thinking Newtonianly. The particle has a different time than you do. For the photon no time passed at all. For the photon the distance was zero. If you could be a photon it would appear to you that you not only traveled instantly, but that there was no distance to travel either.

 

[Kangaroo Feathers]

However we are not light surfing photons, hence relative

Relative to an outside observer, yes.