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Who's familiar with the conversion? - "In 15 years' ship-time they could reach Andromeda

 
 
maxdancona
 
  3  
Reply Mon 16 Nov, 2015 02:03 pm
@oristarA,
Oristar, there is an interesting discussion here about how Science works.

Part of Layman's problem is that he rejects science without understanding it. And yet he brings up an interesting point-- that of what science has to say about the "truth".

Science only knows what can be tested by experiment. By experiments we can define what is "correct" (of course isn't the same as "truth"). A theory is correct if and only if it can make predictions that are confirmed by experiment that no other theory can make... and of course there have been techniques developed by scientists to define this very clearly.

The best way to understand science is to understand the experiments used to test the ideas in science. If you want to ask a question in science... you really need to understand what experiment would answer this question. If you can't define an experiment (at least in concept) to get an answer the the question isn't a scientific question.

Layman seems to be saying that one frame of reference is the "true" frame of reference. This is not a scientific idea unless there is some experiment we can do to distinguish the "true" frame of reference from any other frame of reference. This was tried around the year 1900 (just before Einstein), the Michelson-Morley experiment famously failed to detect the one "true" frame of reference.

Does this topic interest you Oristar?

I won't continue if no one is interested.
layman
 
  0  
Reply Mon 16 Nov, 2015 02:09 pm
@maxdancona,
Quote:
A theory is correct if and only if it can make predictions that are confirmed by experiment that no other theory can make


By that definition, special relativity is not "correct."


However, by that definition a theory of relative motion which posits absolute simultaneity could be correct. It accurately makes predictions that SR does not, and cannot, make (in addition to making all the same predictions as SR does when SR can be used).
layman
 
  0  
Reply Mon 16 Nov, 2015 02:19 pm
@maxdancona,
Quote:
This was tried around the year 1900 (just before Einstein), the Michelson-Morley experiment famously failed to detect the one "true" frame of reference.


This, among other things in you last post, is wrong, if you're trying to pass it off as current.

Read what nobel-prize winning physicists like George Smoot have to say about the "rest frame of the cosmos" (aka the CMB). Astronomers do NOT use SR in making their calculations. They use an AST theory. The same is true of the global positioning system. Were you born in 1900?
0 Replies
 
layman
 
  0  
Reply Mon 16 Nov, 2015 02:25 pm
@maxdancona,
Quote:
If you can't define an experiment (at least in concept) to get an answer the the question isn't a scientific question.


You're not even asking the relevant question, Max, so it doesn't even matter if it's "scientific" or not. The reason you don't ask the right question is because you don't understand the underlying concepts.

Newton was well aware (as was Lorentz) that we can only detect relative motion. He freely admitted that we would never be able to detect, with certainty, any "absolutely motionless" object. Yet he built a fabulous scientific structure of mechanics nonetheless. You don't NEED to know that to do science.
0 Replies
 
layman
 
  0  
Reply Mon 16 Nov, 2015 02:31 pm
@maxdancona,
Quote:
This was tried around the year 1900 (just before Einstein), the Michelson-Morley experiment famously failed to detect the one "true" frame of reference.


This experiment was not designed to, and did not intend to, detect an aether. It was designed to detect the motion of the earth (as in orbit around the sun, for example).

Again, you don't seem to understand the meaning or purpose of experiments that you know occurred. Knowing the names of the experimenters, by itself, doesn't take you very far, eh?
0 Replies
 
layman
 
  0  
Reply Mon 16 Nov, 2015 03:55 pm
@layman,
Quote:
However, by that definition a theory of relative motion which posits absolute simultaneity could be correct. It accurately makes predictions that SR does not, and cannot, make (in addition to making all the same predictions as SR does when SR can be used).


Which, incidentally, tends to highlight another problem (which I have mentioned, without elaboration), with the article Oris cited.

Acceleration is treated as being absolute, not relative, by SR. Hence SR only applies to objects in inertial states.

"Science" can still make calculations by applying the LT to accelerating objects, however. It's easy. Just use an AST--an absolute simultaneity theory (of relative motion). But, at that point it HAS to drop SR as a theory. It can't work anymore.

In this problem, by hypothesis, the ship is undergoing "constant acceleration." Yet the math used to calculate the times and distances involved is using SR formulations. SR can't, by it's own axioms, be applied to this situation.
0 Replies
 
oristarA
 
  5  
Reply Tue 17 Nov, 2015 12:23 am
@maxdancona,
maxdancona wrote:

Oristar, there is an interesting discussion here about how Science works.

Part of Layman's problem is that he rejects science without understanding it. And yet he brings up an interesting point-- that of what science has to say about the "truth".

Science only knows what can be tested by experiment. By experiments we can define what is "correct" (of course isn't the same as "truth"). A theory is correct if and only if it can make predictions that are confirmed by experiment that no other theory can make... and of course there have been techniques developed by scientists to define this very clearly.

The best way to understand science is to understand the experiments used to test the ideas in science. If you want to ask a question in science... you really need to understand what experiment would answer this question. If you can't define an experiment (at least in concept) to get an answer the the question isn't a scientific question.

Layman seems to be saying that one frame of reference is the "true" frame of reference. This is not a scientific idea unless there is some experiment we can do to distinguish the "true" frame of reference from any other frame of reference. This was tried around the year 1900 (just before Einstein), the Michelson-Morley experiment famously failed to detect the one "true" frame of reference.

Does this topic interest you Oristar?

I won't continue if no one is interested.




Of course it does, Max, so please continue this cosmic journey.
The thinking pattern of yours is pretty close to that of a scientist, while that of Lay's is much similar to that of a novelist. Wink
layman
 
  -1  
Reply Tue 17 Nov, 2015 12:34 am
@oristarA,
Quote:
...that of Lay's is much similar to that of a novelist.


Does that mean you don't understand what I'm saying Oris, or just that you've decided it's all fiction?
oristarA
 
  2  
Reply Tue 17 Nov, 2015 02:27 am
@layman,
layman wrote:

Quote:
...that of Lay's is much similar to that of a novelist.


Does that mean you don't understand what I'm saying Oris, or just that you've decided it's all fiction?


Before I answer this question, would you like to give us the definition of science in your mind?
Please be honest: You write down the definition directly from your mind and keep away from searching online or checking it out from other sources such as books, dictionaries...
layman
 
  0  
Reply Tue 17 Nov, 2015 08:07 am
@oristarA,
Quote:
Before I answer this question, would you like to give us the definition of science in your mind?


The problem of "demarcation" has never been satisfactorily resolved, Oris, and I aint gunna try to do it all by my own self now? I would say that you can't be a good scientist without a critical mind, though.

What's your definition?
oristarA
 
  0  
Reply Tue 17 Nov, 2015 10:50 am
@layman,
layman wrote:

Quote:
Before I answer this question, would you like to give us the definition of science in your mind?


The problem of "demarcation" has never been satisfactorily resolved, Oris, and I aint gunna try to do it all by my own self now? I would say that you can't be a good scientist without a critical mind, though.

What's your definition?


You have a critical mind, Lay. Yet this critical mind of yours is artistically, not scientifically. Your hesitation helps to prove this possibility.
In the closing of this post, I've written down my definition of science directly from my memory (while keeping away from searching online or any other sources of information). I choose the white color for the font so that you will not see it directly with your eyes until you select them.
Please don't select my definition and read it before you've typed out yours (once having written down, POST IT and do not edit it please! Then go read my definition.)
Now it is your turn to type down the definition of science directly from your memory without consulting any other sources of information (man and material alike).

Do the same, Max, if you're interested.















































































Science is a systematic enterprise that builds and organizes knowledge in the form of testable explanations and predictions about the universe.
maxdancona
 
  2  
Reply Tue 17 Nov, 2015 11:09 am
@oristarA,
I think this is my definition of science (from my post of the top of this page).

Quote:

Science only knows what can be tested by experiment. By experiments we can define what is "correct" (of course isn't the same as "truth"). A theory is correct if and only if it can make predictions that are confirmed by experiment that no other theory can make... and of course there have been techniques developed by scientists to define this very clearly.


URL: http://able2know.org/topic/301703-8#post-6070142

layman
 
  0  
Reply Tue 17 Nov, 2015 11:10 am
@oristarA,
Quote:
Yet this critical mind of yours is artistically, not scientifically


Beyond that assertion, Oris, can you answer the question I asked, which was, in part, "do you understand what I am saying?"

I don't think anything I've said on this topic is "artistic" at all. I'm simply speaking prosaically; nothing poetic about it. I'm speaking literally, not in terms of metaphors, allusions, vague symbolism, etc.
maxdancona
 
  2  
Reply Tue 17 Nov, 2015 04:39 pm
@oristarA,
So, Oristar, do you feel comfortable with the idea of Galilean relativity?

One example of Galilean relativity is to imagine two spaceships.

Person A (on spaceship A) notices that each second Person B gets 20 meters closer. Person A assumes that he is stationary and concludes that Person B is moving toward him at 20 m/s.

Person B notices that each second person A gets 20 meters closer and assumes that she is stationary and that Person B is moving at 20 m/s.

The problem that each has is that there is no experiment possible that either person could perform to say that he is right.... and there is no experiment possible to show that either person is wrong.

Of course science can make the claim that either is moving within a specified frame of reference... once you choose an arbitrary frame of reference, there is any number of experiments, from measuring how distance changes directly to using sonar to using the doppler effect.

But as long as there is no experiment possible to prove or disprove either persons claim to be stationary in an absolute sense... the question of who is "truly" stationary is not a scientifically valid question.

If there was an experiment that could distinguish a truly stationary person from a not stationary person in an absolute sense, then this would be a valid question.

The claim of Galilean relativity is that laws of mechanics (the branch of physics dealing with velocity, acceleration and motion) work exactly the same, under any experimental conditions, in any frame of reference. If you could devise an experiment where a person who was "truly stationary" could prove the other person, who was not "truly stationary" wrong, then you would disprove Galilean Relativity (an experiment that worked differently for person A from person A's perspective then it did for person B from person B's perspective would do the trick... but there is no such experiment).

But since there is no way by experiment to distinguish between "truly stationary" and "not truly stationary"... the term "truly stationary" has no meaning in any scientific context.

Does this make sense?
maxdancona
 
  2  
Reply Tue 17 Nov, 2015 04:46 pm
@maxdancona,
There is a real life example that illustrates the problem (I used to use this thought exercise with my students to introduce relativity)..

Imagine you wake up on a sealed maglev train on a perfectly straight track. The windows are sealed shut and the train, when it moves, is completely vibration free. The train itself acts as a Faraday cage (meaning no information comes from outside the train).

However in the train you can have a full physics lab with any piece of equipment that you want.

What experiment can you do that can tell you if the train is stopped or if the train is moving what direction it is moving? (Hint: There is no possible experiment).

This is a good though exercise to work through the fact that you can't make a scientific claim... unless you can back it up with an experiment.
layman
 
  0  
Reply Tue 17 Nov, 2015 05:01 pm
@maxdancona,
Quote:
The problem that each has is that there is no experiment possible that either person could perform to say that he is right.... and there is no experiment possible to show that either person is wrong.


Without commenting on anything else you've said, Max, this is incorrect. Ever hear of the Hafele-Keating experiment (involving clocks aboard airplanes)? The global positioning system which involves multiple satellites orbiting in space, maybe?

If you know which clock runs slower, then you know it is the one moving, relative to the (faster) clock it's compared to. So special relativity would say, anyway (and other equally "provable" theories of relative motion).

They have refined the precision of atomic clocks to the point where they can measure a clock in a car going 35 mph to be running slower than one which stays on the sidewalk.

If a person claimed that the clock on the sidewalk was "really" the slower clock, he would be WRONG.
layman
 
  0  
Reply Tue 17 Nov, 2015 05:23 pm
@maxdancona,
I'll address this question to Oris:

First we have this situation:

Quote:
The train itself acts as a Faraday cage (meaning no information comes from outside the train).


Then we end up with this conclusion:

Quote:
What experiment can you do that can tell you if the train is stopped or if the train is moving what direction it is moving? (Hint: There is no possible experiment).


Does that prove anything about what can be known to you, Oris?

Suppose you were allowed to open a train window, and saw trees, fence posts, etc. going by. What could you "tell" then?

Is it any mystery that a blindfolded man can't see an object that is right in front of his eyes? Does it prove that he can "never see" (never know) what is right in front of his eyes?
layman
 
  0  
Reply Tue 17 Nov, 2015 06:23 pm
@maxdancona,
Quote:
So, Oristar, do you feel comfortable with the idea of Galilean relativity?


I'll make one more post on this, which kinda helps summarize both of my last posts.

Was Galileo trying to show that you could not tell which of two objects was "really moving?" Hell no! Quite the opposite. After being forced, under threat of torture, to renounce his claim that the earth "really" moves, he is said to have muttered, under his breath, as he was leaving the inquisition chamber: "And yet it moves!"

So, then, what was he trying to prove? The law of inertia, that's what. He gave an example (now referred to as the "parable of the ship") where a guy in a closed cabin below deck on a (uniformly) moving ship at sea would not be able to tell if he was moving. I won't go into more details about that right now. If you want to know about how that relates to the concept of inertia, you can look it up online.

But I will note that he went on to say that, once the sailor went up to the deck of the ship, saw the ship's sails fully billowed, and saw the trees, cities, mountains, etc. which were fixed to the earth going by, THEN he would know that he was moving. He didn't say he would know that he was "at rest" and know that the cities, not him, were moving (as SR does).
maxdancona
 
  3  
Reply Tue 17 Nov, 2015 06:31 pm
@layman,
Hmmm Layman, we already discussed this. You are confusing inertial and non-inertial frames of reference. Galilean relativity only refers to inertial (constant velocity) frames. The twin paradox involves acceleration.

You can dither around if you want... but you have a basic challenge. In order to truly prove that you are right you need to propose an experiment that one person can use to prove that they are truly stationary.

In the space ship example, what experiment can Person A use to prove that he is the one who is truly motionless. (You can use the twin paradox as part of this experiment if you like).

Your challenge is to come up with such an experiment that can tell us that one person is absolutely correct, and another is wrong in their claim that they are "truly" stationary.

If you can do that, you win.
maxdancona
 
  2  
Reply Tue 17 Nov, 2015 06:35 pm
@layman,
Talk about taking things out of context.

0 Replies
 
 

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