Robittybob1

But if the traveling twin can complete his journey quicker and hence return to his brother younger because at some stage the distance was shorter I think it can be argued there are leftover effects both from the time dilation and length contraction.

I am beginning to think this is only part of the answer. There is this stage too where they both observe the other's meter as being shorter. But can we explain it in terms of the traveling twins, the same ones who come back from their star journey one younger than the other? Who has length contraction then?

Edit by mod Please use spoilers - there are two lots of info about usage above

You know I have been looking into this from a new perspective lately and it is to do with time. When they have relative velocity they are traveling with different coordinates of time and hence they view their mates rulers as shorter than their own (possibly but they don't know how long they were to begin with) for it is only in cases like the Twin Paradox where the scientists were together to begin with, that they have had a chance of calibrating their rulers in the first place and then to get the speed difference between them one or both of them have to accelerate. When they then come back past each other they will know who has accelerated. When that happens I might understand it a bit more.

I'm not denying length contraction but a situation where a meter ruler will measure 2m as a meter. You see if you can find a respected scientist person to agree with you. That is because the ruler is actually (physically) shorter, to the observer it is no longer a meter long and therefore it doesn't have a meter in length any more. But from the perspective of the traveling scientist the ruler still measures a meter for everything has contracted by the same proportion.

That is why I put it in "" to show I didn't mean it as it read. Bluemercury may have felt pressured even without pressure being applied. My comment was for Ophiolite principally, I'm sure he will know what I mean.

I think you are wrong about this, a meter ruler will always measure a meter.

Which means you have to also think of the answer. You can't just say "he will now measure the star as being 5 ly away" without a way of doing it.

Yes I have lost track of which puzzle we were working on, but I think I'd always start with 2 balls and when you notice the odd one you only need to compare it to any other one to see if it is heavy or light.

How does the person on the craft measure the distance to another star?

All I see is Ophiolite "making" someone leave, and since he didn't he said something about putting him on ignore. He hasn't changed. Best of luck with your conversation.

How can he measure that the star is only 5 ly away? Is the star the same distance away no matter in what direction he is traveling? When we measure distance it is at a point in time, we don't make allowances for velocity. Does he measure the length of his spacecraft is also shorter?

Does it matter as long as there are an even number of balls and there is an imbalance So start with 2 balls one on each scale are they the same? if they are balanced place them both on the one pan and weigh 2 more. if they are balanced place them both on the one pan and weigh 4 more. if they are balanced place them both on the one pan and weigh 8 more. Total 16. if they are balanced place them both on the one pan and weigh 16 more. Total 32. At some point you can't keep on doubling it. so then you just split what is remaining in two and weight them. Plus a bit more mucking around.

The handler looks a bit like Ronnie Barker of the Two Ronnies.

You haven't changed!

I just want to focus on that bit. You speed up and notice length contraction; I don't believe you've got that right.

Have you been in a moving vehicle?

I can see why it is easier to explain this when you think of time having three dimensions. Length contraction is only one dimensional

I don't believe you can do it in 5 weighings!

Are you just a kid? What you describe will be what happens in an accelerated vehicle. OK you explain to me why it is not directly above?

What are you grinding it with? I'm not stupid nor ignorant. All the Cuban churches rang their bells when the announcement was made.

Well now you've changed your tune! Compare what you have just said to what you wrote in the OP. This why I have been asking you to check your work. So now the traveling person checks to see if the light clock (ball thrower) is aligned properly.

You still haven't answered my question - if the observation of vertical is made by the outsider how is an adjustment going to be made? If you really set the experiment up as you propose after the ball hits the roof it will bounce back down at an angle too and you won't have a light clock equivalent.

My axe is rather sharp by now!

Did you ask him who he was?