Robittybob1

Is there an effect due to where the synchronization and calibrations took place? I still feel an alien craft would have different standards and so we can't compare two complete strangers. Relativity will still be tested for we want to measure the closing speeds of each of them measured by each of them. Will the radar gun on both sites measure the same reading or a different one. We also need to see how these guns work at some stage. OK we could use LIDAR machines http://en.wikipedia.org/wiki/LIDAR_speed_gun#How_police_LiDAR_guns_work The pulses may have to be separated by a bit more or else the return signal will be too late. We know even at the speed of light a return trip from the Moon will be a little over a second and I'd say we could look at the relative motion both going away and coming toward the ISS so we have a good 3 second window to measure the speeds. The time of flight of each pulse will depend on distance so if we want a pulse to go out and come back before the next and final pulse is sent the timing has to be right for the craft needs only travel one distance but the light pulse has to go twice the distance (there and back). So if Bob has just come past the Moon heading toward the ISS at 0.8 c he is only going to take another 1.25 seconds to travel that distance, but the light pulse will take a second to get there and a second back, so the LiDAR will need to be fired when Bob is still making his approach to the Moon so the light pulse is already there at the moon just as he is passing there, so the light pulse will return just in time for Alice to send another pulse before he passes crazily close to the ISS. I get the feeling for ease of calculation we had better use slower speeds so we can get the timing of the pulses right.

Regardless as to who is moving relative to the Earth? Remember all instruments were calibrated such that the Earth was at rest. Even the ISS is so close to at rest we will ignore the time differences between Houston and the ISS. (No need to say "Houston we have a problem".)

I have not done the calculations as yet but if allowed we will go through them step by step. Here I will propose a thought experiment. It is similar to the Twin Paradox situation. The twins ages are synchronized because they start off on Earth together. To know anything about rates of velocity the space travelers would need to at some stage synchronize their clocks and calibrate their measurements of distance and speed so we would give them both a calibrated radar speed camera recorder before they set off on the long journey to the closest star. To test out the equipment one twin (Bob) flies out to the Moon and back and on the return pass he buzzes Alice on the ISS at 0.8 the speed of light. Do both of them measure the pass as being at the same speed? Lets see if we can use the speed cameras to find out.

I know that is the standard approach but if length contraction is considered normal why is so difficult to think of speed variation. As I drive to work I noticed as I allowed time to slow down I would pass more distance in the same amount of time so that means even though my speedo says 100 km/h I would actually be going faster than what the speedo reads rather than having to think the power poles were physically closer together. Can someone really explain if that was the case why physics breaks simply by looking at the situation from a different perspective? The diagram clearly shows more distance was traveled in a dilated second and there was no logical connection to assume that is solved by length contraction. (I would be willing to start a thread specifically on this topic, if necessary.)

No not if you are tone deaf.

We measure the traveling person moving at "v"/sec but the driver moves V*gamma in one of his dilated seconds, are we really sure he measures his speed at "v"/sec or could it really be "v"* gamma/sec? How could the traveling person check his speed? does he have to take his speed measurement to be the same as ours? (the section of the YT that I question is from 5:00 to 6:14) It seems logical to have two things with relative motion to be travelling with the same speed with respect to each other but if each took their own speed measurements using their own clocks would they still come out the same? The hypothesis to check is that there is no such thing as length contraction due to relative motion but only different absolute rates of velocity.

Failed again! Then some more success!

My question is do you think length contraction really happens? What I see in the YT clip is that time is dilated and the ship goes further in dilated second . Could length contraction be better explained better by showing differing relative speeds rather than than saying the distance to a star is altered by relativistic speeds?

I'm not sure,

Second check it's failing - sorry

I have also done it in 4 weighings but only if it is possible to track individual ball's identity as you have done. So you win.

In the second round what does "good" mean? is it a ball named "Good" for no reason?

I still see lots of errors in your tables, sorry.

So you have labeled your balls with the letters of the alphabet, was that allowed? Do they need to be labeled? Or could you work with the groups as I did "just take any 5" not a specific 5? As the OP said "We have Only a SIMPLE BALANCE and nothing else to use", so we don't have a pen either.

It looks wrong to me.

I think you are thinking of orbital energy or even instantaneous tangential velocity, that stays the same. Late last night I watched a youtube video explaining length contraction and I finally could see the reason it has been causing all the trouble it has. Have a look at this one when you can for my explanation will be referring to it and a similar diagram to it."Special relativity: time dilation and length contraction" by drdwittman @

Now I am confused. I thought there has a lot of talk about saying the rest mass stays the same!

That is a point as long as it is prior knowledge. I couldn't understand that. Now for the perfected run!

You are changing velocity a vector quantity, as opposed to speed or direction when considered separately.

Correct That is if you want to know which one it is and its sign, is it heavier or lighter.

Are you one of these "Nuke them" people?

Energy has a gravitational effect as long as there is no motion, energy involved with the motion (kinetic energy) doesn't seem to affect the rest mass at any stage. Is that also right?

They explain that using words like "asymmetry", for even though there was relative motion affecting both parties only one went through the acceleration which broke the symmetry of the situation.

Setting up post Since it is not too late to try! I will continue on from where I left off before http://www.scienceforums.net/topic/86946-solve-this-if-you-can/page-3#entry842811

You won't see much difference in a human body in just 7 milliseconds. If the journey to the stars can be made shorter simply by going faster it does matter a lot. For it seems to suggest star travel becomes possible for the enormous distances and times involved can be made shorter.