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# I need time dilation help please? watch

1. (Original post by AlbertXY)
Yes its explicit, it contradicts present theory by its own theory, If time dilates and a planet X had say half a length of second compared to our second length, then they would measure speed to be different.
No, it contradicts itself and hence is necessarily false. The speed cannot be the same but also different.
2. (Original post by Implication)
No, it contradicts itself and hence is necessarily false. The speed cannot be the same but also different.

I know , it is your present information that makes this so, it is not my contradiction, it is sciences contradiction.

The speed of light is the same for all observers, but if observers are disagreeing on the length of a second, they are disagreeing on the speed of light, they in their reference frame will record a different speed because they have a different length of a second than we have if they used the Caesium to record time and time events.

We both have to agree that the length of a second is an invariant or we have to disagree on speed. I do not thing we can disagree on speed.
3. (Original post by AlbertXY)
I know , it is your present information that makes this so, it is not my contradiction, it is sciences contradiction.

The speed of light is the same for all observers, but if observers are disagreeing on the length of a second, they are disagreeing on the speed of light, they in their reference frame will record a different speed because they have a different length of a second than we have if they used the Caesium to record time and time events.

We both have to agree that the length of a second is an invariant or we have to disagree on speed. I do not thing we can disagree on speed.
no no no

Speed = distance over time. If they agree on speed, but not distance, then they must also disagree on time.
4. (Original post by AlbertXY)
I know , it is your present information that makes this so, it is not my contradiction, it is sciences contradiction.
The contradiction was explicit in your writing and referenced nothing I said or any 'present information'. However, it sounds like you are simply communicating what you mean poorly.

The speed of light is the same for all observers, but if observers are disagreeing on the length of a second, they are disagreeing on the speed of light, they in their reference frame will record a different speed because they have a different length of a second than we have if they used the Caesium to record time and time events.
Saying the speed of light is the same for all observers means that they agree on the speed of light; they observe/record it to be the same no matter how they are moving.

It can be shown (and it has been shown many times) that people in different reference frames do record the same speed of light. If your model predicts that they would record different speeds, your model disagrees with experiment and cannot be considered science.

If I fire a beam of light forwards and stand still, I see it travel at 299 792 458 m/s forwards. If I fire a beam of light forwards and then move backwards in my rocket at 150 000 000 m/s, I still see the beam travel forwards at 299 792 458 m/s. This is confirmed by experiment.

We both have to agree that the length of a second is an invariant or we have to disagree on speed. I do not thing we can disagree on speed.
One second is invariant by definition, but observers in different reference frames record different numbers of seconds between the same events.
5. (Original post by Kyx)
no no no

Speed = distance over time. If they agree on speed, but not distance, then they must also disagree on time.

You can't disagree about a distance, I know d/t , that is the whole point.

d/t1=x

d/t2=x

+ve(c)=1s

-ve(c)=1s

t net difference = 0

now if t2 is different than t1 the speed will be measured different.
6. (Original post by AlbertXY)
You can't disagree about a distance, I know d/t , that is the whole point.

d/t1=x

d/t2=x

+ve(c)=1s

-ve(c)=1s

t net difference = 0

now if t2 is different than t1 the speed will be measured different.
if time = 1 and distance = 1, speed = distance/time = 1/1 = 1

if time = 2 and distance = 2, speed = distance/time =2/2 = 1
7. (Original post by Implication)

One second is invariant by definition, but observers in different reference frames record different numbers of seconds between the same events.

You can't be understanding because you just said it. If your second is different you measure speed different.
8. (Original post by Kyx)
if time = 1 and distance = 1, speed = distance/time = 1/1 = 1

if time = 2 and distance = 2, speed = distance/time =2/2 = 1

No, you are considering it wrongly,

f time = 2 and distance = 1, speed = distance/time =?
9. (Original post by AlbertXY)
You can't disagree about a distance, I know d/t , that is the whole point.

d/t1=x

d/t2=x

+ve(c)=1s

-ve(c)=1s

t net difference = 0

now if t2 is different than t1 the speed will be measured different.
The whole point of SR is that the speed of light is the same in all reference frames. This is a fact that has been experimentally confirmed explicitly and implicitly literally millions of times. It does seem counterintuitive for the reason you say: 'if speed is constant, what the fluff happens with distance and time? They're intimately related!'

And the answer is that time dilates and length contracts. Obviously, as you seem to be trying to demonstrate with your arithmetic, if only time dilated we would have a problem!
10. (Original post by AlbertXY)
You can't be understanding because you just said it. If your second is different you measure speed different.
The actual speed is the same, regardless of units. I could say that the speed of light is 3 blurgs, and I will always measure it as 3 blurgs NO MATTER WHAT!
11. (Original post by AlbertXY)
No, you are considering it wrongly,

f time = 2 and distance = 1, speed = distance/time =?

1/2 = 0.5

12. (Original post by AlbertXY)
You can't be understanding because you just said it. If your second is different you measure speed different.
No, because you measure distance differently too.
13. (Original post by Kyx)
The actual speed is the same, regardless of units. I could say that the speed of light is 3 blurgs, and I will always measure it as 3 blurgs NO MATTER WHAT!

I said the actual speed is the same, but according to observers with different rates of time, the measurement d/t is different.
14. (Original post by AlbertXY)
I said the actual speed is the same, but according to observers with different rates of time, the measurement d/t is different.
lets assume that everyone has the same units for time and distance

Then the speed of light will ALWAYS be 3x10^8 m/s , no matter what
15. (Original post by Kyx)
lets assume that everyone has the same units for time and distance

Then the speed of light will ALWAYS be 3x10^8 m/s , no matter what

Yes if they all had our units of measurement.

However try considering what the speed would be if we all had a second that was half the rate, does the m/s then not double?
16. (Original post by AlbertXY)
Yes if they all had our units of measurement.

However try considering what the speed would be if we all had a second that was half the rate, does the m/s then not double?
That is irrelevant since the actual speed is not changing.
17. (Original post by Implication)
No, because you measure distance differently too.

NO, all observers would agree that a yard stick is a yard.
18. (Original post by Kyx)
That is irrelevant since the actual speed is not changing.

It is relevant when you consider who's defining the speed, are you to say that the speed of light we measure is even remotely correct ? how do you know it is even fast? fast relative to what?

The Universe defines the universe it is not of us to define speed to being absolute to a time frame made by us.

If you did the maths you would find that presently the speed of light is faster than time,
19. (Original post by AlbertXY)
You can't disagree about a distance, I know d/t , that is the whole point.

d/t1=x

d/t2=x

+ve(c)=1s

-ve(c)=1s

t net difference = 0

now if t2 is different than t1 the speed will be measured different.
(Original post by Implication)
No, because you measure distance differently too.
To clarify, you're doing the wrong calculation. Technically speed is the derivative of position with the respect to time, but over small enough changes in position we can approximate it as the change in position - distance - over the change in time. In this case assume is the position of light. Then

In your notation, you can write this as

.

Now consider two different observers in difference reference frames. The first observer, Alice, measures the speed of light to be and the distance and time to be and respectively. The second observer, Bob, also measures the speed of light to be (by the postulate of SR, as confirmed experimentally). He measures the distance and time to be and . Where is the contradiction here?

.

We only need if , but this is manifestly not the case for different reference frames! There are infinitely many variations that leave the speed of light invariant. For example, if and ,

and there is no problem.

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