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Perhaps once you have shown (in New Theories please) why earth has an intrinsic nature outside the laws of physics - then we can start afresh.
Yes there are plenty of ways to question accepted ideas. Arguments from incredulity and naked disbelief are not included - most especially on the main fora. post as much as you like in New Theories - just keep the main fora to Science Q&A
To answer your last point - you are privileging your notions (and the common and nature notions of humanity) over the scientific method.
It has be shown countless times that ideas of intrinsic nature, of an immutable realism, of absolute time and space etc are useful, practically universal, easy to accept, and wrong. Perhaps once you have shown (in New Theories please) why earth has an intrinsic nature outside the laws of physics - then we can start afresh.
A far better guide in science is logic. Once you know something is true (by observing or measuring it), you can logically figure out its consequences.
In philosophy, Realism, or Realist or Realistic, are terms that describe manifestations of philosophical realism, the belief that reality exists independently of observers.
If the bus is moving at 86.6% the speed of light, the bus will be half its normal length as measured in your frame of reference.
If you imagine a fast moving thing travelling past you at a distance rather than heading towards you or away from you, there will be no Doppler complications to get in the way of seeing the length of that object. For example, imagine that you're standing in the middle of a straight road (with no traffic on it - please be careful if you're doing this for real), while ahead of you there is a crossroads, and on the road which crosses yours there is a fast-moving bus which is crossing your road. You can see its length without the Doppler shift affecting it as the light from both ends of the bus has exactly the same distance to travel to reach your eyes. If the bus is moving at 86.6% the speed of light, the bus will be half its normal length as measured in your frame of reference.
'Mainstream' in terms of length contraction is Einstein's special relativity, which does predict length contraction. Criticisms of that idea should be kept to New Theories, as mentioned above.
“It appears to me that “real” is an empty meaningless category (drawer) whose immense importance lies only in that I place certain things inside it and not certain others."
However, what in fact happens is that the distance to Alpha Centauri becomes shorter for the person in the spacecraft.
David Cooper:QuoteIf the bus is moving at 86.6% the speed of light, the bus will be half its normal length as measured in your frame of reference.May we at least use language precisely in the critical analysis of intrinsic vs extrinsic properties?"The bus will be" is very different than "the bus will appear.""... as measured in your frame of reference" means "as it will appear to you" (the extrinsic effect of length contraction.) The bus does not actually intrinsically shrink because of the way it would appear to you.
Quote from: David Cooper on 10/09/2012 19:49:30If you imagine a fast moving thing travelling past you at a distance rather than heading towards you or away from you, there will be no Doppler complications to get in the way of seeing the length of that object. For example, imagine that you're standing in the middle of a straight road (with no traffic on it - please be careful if you're doing this for real), while ahead of you there is a crossroads, and on the road which crosses yours there is a fast-moving bus which is crossing your road. You can see its length without the Doppler shift affecting it as the light from both ends of the bus has exactly the same distance to travel to reach your eyes. If the bus is moving at 86.6% the speed of light, the bus will be half its normal length as measured in your frame of reference.You should know distance between me and the crossroads,you should know normal length of the bus then you can calculate length of the bus in my frame of reference.I see the rejected middle of the bus under an angle of 60 degrees relatively of arrival line of photons of the crossroads.I can't see photons radiated by the bus on the crossroads with photons of the crossroads under the same angle.
Anyone who believes that Earth is flattened like a pancake (in any case) has decided in favor of Einstein's version of idealism and has abandoned the realism which grants the world an existence and intrinsic properties (shape, size, etc.) independent of observation/frames of reference.
...and the road crossing the road the bus is on can't be straight, even though we know it's straight. What's going on there?
A good post, old guy, but one bit's maybe wrong (depending on how you interpret the shape of a pancake.
X will be Y as measured in Z" qualifies the word "be" with "as measured in", so it's perfectly clear that it's referring to the measurement being Y. An example that illustrates this more clearly is: "John is 32 inches as measured round the waist using this faulty tape measure" - this does not mean he is actually 32 inches round the waist.
Let's keep it on the topic without such irrelevant distractions, please.
The whole point of my criticism of large scale length contraction is that there is a world of difference between how something appears or how it is "measured in" various frames and the naturally occurring, intrinsic properties ( including shape and size) of an object as it was formed by the laws of physics (or built) in the first place.
This point was made abundantly clear in my example (in the Physics section version of this thread) of the alien probe retrieval project."As it was measured" in Earth's frame (as it approached at near 'c'), it appeared to be 10 meters long. If it were actually, intrinsically 10 meters long, as it was built, it would fit into a 10+ meter (for sliding in room) retrieval cargo bay. But once the shuttle pulled alongside the probe (at rest with it, in same frame of reference) it would have been seen as it actually was, much longer than the 10 meters "as it was measured" from earth.The retrieval project would have wasted its time and money to send a shuttle with a 10 meter bay to get it. This was a practical illustration of the difference between the intrinsic length of the probe, as it was built, and the extrinsic appearance of the probe as "length contracted", as seen from Earth. This point was successfully ignored in the physics section thread. The mantra is simply repeated (with metaphorical hands over ears), "It all depends on frame of reference," or, "There is no reality independent of measurements from various frames."
This passes for "mainstream science" these days, because criticism of Einstein's philosophy, to the above effect (see quote in thread above), is not allowed as legitimate discussion of SR theory in this forum.
Ps; I propose a " contra-mantra" as stated in summary of my last post:"Earth (and other solid objects) do not change shapes(/lengths) to accommodate all varieties of observational points of view."
Please keep your comments within the parameters of the debate as I have conceived it in both of my threads. This is not the place for your pet theories. My argument is not a personal pet project to debunk SR, as I have explicitly stated several times. My argument is based on realism about the intrinsic properties of objects and the distances between them, as I have quoted Wiki on the meaning and elaborated the implications.
Quote from: simplified on 11/09/2012 15:10:45Quote from: David Cooper on 10/09/2012 19:49:30Edit: correction - it's 60 degrees forwards rather than backwards for the direction in which we're seen from the bus (from the point of view of someone on the bus), but 60 degrees behind the bus that the laser has to be pointed, so it isn't pointed towards the target at all.Someone on the bus should send his photons at 150 degrees relatively of own motion direction.
Quote from: David Cooper on 10/09/2012 19:49:30Edit: correction - it's 60 degrees forwards rather than backwards for the direction in which we're seen from the bus (from the point of view of someone on the bus), but 60 degrees behind the bus that the laser has to be pointed, so it isn't pointed towards the target at all.Someone on the bus should send his photons at 150 degrees relatively of own motion direction.
Edit: correction - it's 60 degrees forwards rather than backwards for the direction in which we're seen from the bus (from the point of view of someone on the bus), but 60 degrees behind the bus that the laser has to be pointed, so it isn't pointed towards the target at all.
Someone on the bus should send his photons at 150 degrees relatively of own motion direction.