Experiment and Theory vs. Reality

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Originally posted by HallsofIvy
Same reason that would be given for questions on any physics point:
"That's what the experimental evidence says". Arguments about "reasonableness" cannot stand in the face of experimental evidence. (And the experimental evidence in favor of relativity is overwhelming.)
I disagree. Experimental agreement is not grounds for establishing a theory. There needs to be a reason, based on some principle, that can explain why these things are true.

For example, if I am in a space ship traveling the speed of light relativity says that I can not walk from one end of the ship to the other. What is the reasoning being this? If all you can say is that there is experimental evidence then your understanding is not complete.

It is extremely strange that although SR has been arround for almost 100 years no one has conclusively answered this question. In fact, it seems that there is very little contemplation given to this question which lies at the foundation of modern physics.
 

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  • #2
selfAdjoint
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For example, if I am in a space ship traveling the speed of light relativity says that I can not walk from one end of the ship to the other. What is the reasoning being this? If all you can say is that there is experimental evidence then your understanding is not complete

And if I'm walking across the water of a lake physics says I can't avoid getting my feet wet. Why hasn't science addressed this problem?

Get used to it . You can't be in a spaceship travelling at the speed of light because a spaceship can't travel at the speed of light. Experiment has lots of massive particles accelerated to near the speed of light, relative to the equipment, and they can confirm the physical changes that take place. And relativity does have a theory. It goes:

1. All unaccelerated observers can do physics as if they were at rest.
2. All unaccelerated observers measuring the speed of light get the same number.
 
  • #3
Tom Mattson
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Originally posted by protonman
Experimental agreement is not grounds for establishing a theory. There needs to be a reason, based on some principle, that can explain why these things are true.
You've got it completely backwards. Experimental agreement is what determines "what is reasonable", and it is also what determines our principles that describe the workings of nature. The principles of which you speak are abstracted from the experimental evidence, not the other way around.
 
  • #4
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Originally posted by selfAdjoint
For example, if I am in a space ship traveling the speed of light relativity says that I can not walk from one end of the ship to the other. What is the reasoning being this? If all you can say is that there is experimental evidence then your understanding is not complete


And if I'm walking across the water of a lake physics says I can't avoid getting my feet wet. Why hasn't science addressed this problem?
This is not a good analog because the fact that your feet get wet is not one of the foundations of modern physics.

Get used to it . You can't be in a spaceship travelling at the speed of light because a spaceship can't travel at the speed of light. Experiment has lots of massive particles accelerated to near the speed of light, relative to the equipment, and they can confirm the physical changes that take place. And relativity does have a theory. It goes:
Get used to what? Is this a cop out? I already said that experimental verification is not enough evidence to establish something. If experiementers are able to accelerate particles then there is a highest speed they have reached. This speed is less than the speed of light. How do they know if they go 1% faster things will be the same. All experiment can do is nullify something. It can not establish something conclusively. In order to establish something in all cases you must use reason. An example of this is momentum conservation. This can be established without experiement.

1. All unaccelerated observers can do physics as if they were at rest.
2. All unaccelerated observers measuring the speed of light get the same number.
These are postulates of axioms of SR. Based on these two statements Einstein developed all of SR. I never said that relativity does not have a theory. I said Experimental agreement is not grounds for establishing a theory. There is a difference. Initially, Einstein more or less assumed the two postulates. The first one is not so bad and is establishable via reasoning. The second though is complete speculation. The whole idea behind it is the failed attempt to detect any medium though with light waves travel.

My understanding of SR is very deep because I have thought about it outside the confines of the establishment. If you are constantly surrounded by people saying the same thing, it is difficult to formulate original ideas that are contrary.
 
  • #5
ahrkron
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Originally posted by protonman
I disagree. Experimental agreement is not grounds for establishing a theory.
Maybe a political or a marketing theory, but it is the only grounds for physical theories.

Why do you think that we consider Newton's laws "reasonable"? why do we not use pre-Newtonian ideas? Aristotle postulated many physical principles that were held as truth for a long time. Why do you think we don't use them any more?

Back in those times, youngsters were taught those principles, which surely were reasonable enough to be around for a long time, but what is now regarded as reasonable (and taught to every child through school and action movie sequences) is different.

As long as these principles are not clearly in contradiction with observation, people can learn them and make them part of what they consider "reasonable". It is important to be aware of that. Our neural circuitry comes with no warranty about the adequacy of its favored ideas for describing reality.
 
  • #6
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Originally posted by Tom
You've got it completely backwards. Experimental agreement is what determines "what is reasonable", and it is also what determines our principles that describe the workings of nature. The principles of which you speak are abstracted from the experimental evidence, not the other way around.
We could go back and forth all day saying who is correct. You have provided no evidence for your claims. Only that I have it backwards.

Experimental evidence is not conclusive. It can only eliminate a theory, not establish it. Why? Because if an experiment establishes something it only establishes it in the particular situations the experiment was done in. Pervasive establishments are based on reason. If you can establish something based on a reason then you can establish something in all cases.

For example, to find the extrema of a function you could check all points. The problem here is that there are infinite cases. If you check countless cases you still have countless more to check. Consider a simple parabola that has only one minimum at zero. You check every case except zero and based on all these tests conclude there is no zero. Or you could use reason. Since the point where the tanget is zero must be an extrema all we need to do is find this point. This is established pervasively. We did not need to look at every case but through logic and reason deduced that there is a relationship between extrema and the tanget line.
 
  • #7
russ_watters
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Originally posted by protonman
We could go back and forth all day saying who is correct. You have provided no evidence for your claims. Only that I have it backwards.
Not really. This isn't subject to debate. You are quite free to argue in our philosophy forum how the process of science should work, but the way we described it is the way science does work. Those are the rules and thats the game. If you want to play the game, you have to follow the rules. Try arguing with an umpire about how many strikes should be allowed in baseball and see how far you get. Same thing here.
 
  • #8
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Originally posted by russ_watters
protonman, as others have said, your ideas on what science itself is on the most basic level are deeply flawed.
My ideas on what science is are fine. I know what you people accept and I don't accept them. My understanding of the scientific method is perfect. If you read my posts this is what I am attacking. I leave it up to you to fight back.
In fact, you can look to history to see that your way does not work and the current accepted way does. Preconcieved notions of how the universe should work were the cause of thousands of years of scientific stagnation. Only after we broke out of that cage in the Rennaissance (sp) did our understanding of the laws of the universe start to grow - and grow at an astounding rate.
I have no preconceived notions of how the world should work. It is you that have no understanding of why is meant by reason. Reason is not what should make sense. Reason is looking at the world and based on this ensuring that views do not contradict it.
Your own personal understanding will grow as well if you accept the way science works and work within it. Otherwise you are just spinning your wheelse in place - attacking strawman versions of theories by using thought experiments that aren't allowed by the theory in the first place.
Maybe for you but I don't accept things that I find incorrect. I wouldn'y base my entire view of the world on speculation. That is all your method is. That if we do an experiment N times and the results are the same each time the N+1 time it will be the same. This is not certainty.
QM is a good example of a branch of science that broke all the preconcieved rules of logic and our expectations of how it could be. But the experiments are unequivocable and the theories based on them work. So we must accept it. [/B]
Many theories work but that does not mean that the model is an exact description of reality. The best example is right here in front of us. Newtonain mechanics worked ok for a while. Aristotle worked ok for a while. What makes you think that what you have now is any different. Don't you see the pattern of theories that were later shown to be incomplete or wrong.

Since you seem to be in the advice giving mood I will give you some. You desire for certainty at any cost is the problem. The hardest thing for people to realize is what they have devoted their life to and studied for many years is actually wrong. At least not as valid at once thought. Getting past this point is the hard part and everything else after this lead to the truth.

I have the degrees to back up what I say. I am a physics teacher. Unlike you people, I teach students how to think not what to think.

I have defended against all your views. I challenge you to do the same.
 
  • #9
russ_watters
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Originally posted by protonman
Many theories work but that does not mean that the model is an exact description of reality....

What makes you think that what you have now is any different. Don't you see the pattern of theories that were later shown to be incomplete or wrong....

You desire for certainty at any cost is the problem.
No one here has said anything at all about certainty, exactitude, or infallibility of existing theories. That's not how the scientific method works and we know it.

Newtonain phyiscs was not in contradiction with reality at the time.
Newtonian physics was in fact known to be contrary to reality at the time it was proposed(or soon thereafter). Since we know why it was incomplete, that does not diminish its utility.
 
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  • #10
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Originally posted by protonman
Newtonain phyiscs was not in contradiction with reality at the time. So if this is so why do you accept SR and only Newtonain physics as a low velocity limit?


Because experimental evidence has shown that Newtonian physics is insufficient to explain relativistic phenomena, and that SR predicts what is observed.

The whole idea behind your theories is that they are the same today as tommorow.
Your point?

If science is based on experiemnt and experiemnt is based on observation and observation is based on perception how do you even know your perceptions are correct? Can you prove this experimentally? If not then the foundation of phyics must be abandoned.
I'm sure a philosophy journal might be interested in your theories, but quite frankly I get really tired of the offensive nature of those posters who come on here and deny established scientfic practices because they "think outside the establishment". You are obviously not interested in intellectual discussion, but rather boasting your "superior understanding" of all things science because you aren't a scientist, and aren't "brainwashed" by the orthodoxy.
 
  • #11
russ_watters
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The Scientific Method

Excerpts:
I. The scientific method has four steps

1. Observation and description of a phenomenon or group of phenomena.

2. Formulation of an hypothesis to explain the phenomena. In physics, the hypothesis often takes the form of a causal mechanism or a mathematical relation.

3. Use of the hypothesis to predict the existence of other phenomena, or to predict quantitatively the results of new observations.

4. Performance of experimental tests of the predictions by several independent experimenters and properly performed experiments.

If the experiments bear out the hypothesis it may come to be regarded as a theory or law of nature (more on the concepts of hypothesis, model, theory and law below). If the experiments do not bear out the hypothesis, it must be rejected or modified.
Further, no matter how elegant a theory is, its predictions must agree with experimental results if we are to believe that it is a valid description of nature. In physics, as in every experimental science, "experiment is supreme" and experimental verification of hypothetical predictions is absolutely necessary.[emphasis added]
If the predictions of a long-standing theory are found to be in disagreement with new experimental results, the theory may be discarded as a description of reality, but it may continue to be applicable within a limited range of measurable parameters. For example, the laws of classical mechanics (Newton's Laws) are valid only when the velocities of interest are much smaller than the speed of light (that is, in algebraic form, when v/c << 1). Since this is the domain of a large portion of human experience, the laws of classical mechanics are widely, usefully and correctly applied in a large range of technological and scientific problems.
...and most importantly, the issue here:
III. Common Mistakes in Applying the Scientific Method

As stated earlier, the scientific method attempts to minimize the influence of the scientist's bias on the outcome of an experiment. That is, when testing an hypothesis or a theory, the scientist may have a preference for one outcome or another, and it is important that this preference not bias the results or their interpretation. The most fundamental error is to mistake the hypothesis for an explanation of a phenomenon, without performing experimental tests. Sometimes "common sense" and "logic" tempt us into believing that no test is needed. There are numerous examples of this, dating from the Greek philosophers to the present day. [emphasis added]
 
  • #12
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I'm sure a philosophy journal might be interested in your theories, but quite frankly I get really tired of the offensive nature of those posters who come on here and deny established scientfic practices because they "think outside the establishment". You are obviously not interested in intellectual discussion, but rather boasting your "superior understanding" of all things science because you aren't a scientist, and aren't "brainwashed" by the orthodoxy.
Who said anything about being established? Check up above. It was acknowledged that the idea of certainty is not a reality. Certainty=established.

In addition, it is really great to see you so open to intellectual inquiry. Your views are truly in the spirit of those who seek truth.
 
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  • #13
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Why hasn't anyone addressed this argument?
If science is based on experiment and experiment is based on observation and observation is based on perception how do you even know your perceptions are correct? Can you prove this experimentally? If not then the foundation of phyics must be abandoned. If so how can you establish that perceptions, which are the foundation of experiemental verification, are vefified by experiemnt. How would you know this experiment is valid?
 
  • #14
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Newtonian physics was in fact known to be contrary to reality at the time it was proposed(or soon thereafter). Since we know why it was incomplete, that does not diminish its utility.
Really? That is strange. Who was it that discovered that it was contrary to reality?
 
  • #15
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Perfect answer

Consider how stupid the argument that the only explanation of why light is measured the same by all observers independently of their relative motion is experimental evidence.

Everytime I throw a baseball up it comes down. To an observer this seems very strange. They ask why it comes down I reply because everytime I throw it up it comes down. Is this really an explanation?
 
  • #16
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QU

Originally posted by protonman

In addition, it is really great to see you so open to intellectual inquiry. Your views are truly in the spirit of those who seek truth.
From the tone of your posts it's quite clear to me (and others) that's you're not interested in intellectual discussion. You're here to stir up **** by insulting everyone's education, proclaiming yourself to be above it all because you think outside the box.

If you are really trying to engage in honest philosophizing, then change your tone and you might find people a bit more receptive. Hint: first thing you post shouldn't be to tell everyone how naive they are for blindly accepting their education, and how superior your thinking process is, plus how you've clearly mastered this field and understand it better than everyone who has studied it.

There's a fine line between critical analysis and just plain nonsensical thought.

You also said:

Everytime I throw a baseball up it comes down. To an observer this seems very strange. They ask why it comes down I reply because everytime I throw it up it comes down. Is this really an explanation?
It is confirmation of a fact. Furthermore, we know that our theories of gravity explain very nicely *why* the ball will come back down when we throw it up.

To be quite honest, I don't remember what your original question was, whether it was light travelling at constant speed or light having mass. In either case, these are backed up by theoretical postulates which are confirmed experimentally. Constant speed of light: Maxwell's equations (classical and covariant form). Constant speed of light in all reference frames: Einstein-Lorentz theory. Null mass of photon: renormalizability of U(1) gauge group.
 
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  • #17
Nereid
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protonman wrote (re QM): Many theories work but that does not mean that the model is an exact description of reality.
If they 'work', then there is no experimental or observational data that is inconsistent with the theories. But what then is 'reality'? A good topic for discussion! What is 'exact'? In the lab and in the field, it can have meaning only in terms of the apparatus, equipment etc and the (physical) theories which underlie them.

More fundamentally, how can you tell that a description before you - whether proposed by Einstein, Feynman, Russ, Nereid, vlamir, wisp, or anyone else - is 'an exact description of reality'?
 
  • #18
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Originally posted by Nereid
If they 'work', then there is no experimental or observational data that is inconsistent with the theories. But what then is 'reality'? A good topic for discussion! What is 'exact'? In the lab and in the field, it can have meaning only in terms of the apparatus, equipment etc and the (physical) theories which underlie them.

More fundamentally, how can you tell that a description before you - whether proposed by Einstein, Feynman, Russ, Nereid, vlamir, wisp, or anyone else - is 'an exact description of reality'?
I don't think anyone is arguing that *any* theory is an EXACT theory of reality (except maybe protonman). Newtonian mechanics had limits, as I'm sure does relativity, quantum field theory, etc... These are constantly being pushed and expanded, and periodically comes a paradigm shift where the line of thinking is completely redrawn.

I will be the first one to admit that present theories will be antiquated in 100 years, and that a more complete theory is waiting, through which we'll understand the universe that much better.

HOWEVER, this does NOT invalidate present theory, any more than SR invalidated Newtonian mechanics. Each theory has a range in which its power of predictability applies and holds.
 
  • #19
Nereid
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GRQC wrote: HOWEVER, this [the assertion that today's hot favourite physics theories - GR, QM, ... - will likely be found seriously wanting in the next ~100 years (I'm paraphrasing)] does NOT invalidate present theory, any more than SR invalidated Newtonian mechanics. Each theory has a range in which its power of predictability applies and holds.
Well said!

There's also an 'in the limit' constraint; e.g. GR needs to closely resemble Newtonian mechanics (Nm) 'in the limit' of the range where Nm applies and holds.
GRQC wrote: I don't think anyone is arguing that *any* theory is an EXACT theory of reality (except maybe protonman)
I am kinda hoping that protonman will give us his thoughts on the answer to my question.
 
  • #20
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More fundamentally, how can you tell that a description before you - whether proposed by Einstein, Feynman, Russ, Nereid, vlamir, wisp, or anyone else - is 'an exact description of reality'? [/B]
If somethings description is in accordance with the how the object actually exists.
 
  • #21
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Everytime I throw a baseball up it comes down. To an observer this seems very strange. They ask why it comes down I reply because everytime I throw it up it comes down. Is this really an explanation?
I will explain why I said this.

I asked why the speed of light is measured the same by all observers regardless of their motion relative to the light source. The answers were all something to the effect of 'its been confirmed by experiment.'

My parallel was for a ball thrown up. Just think if someone asked you why a ball falls back to the earth each time it is thrown up. You respond 'because each time I do it is falls back down.' This is what they are saying. It has nothing to do with your statement that gravity is well understood.

You need to read my posts before you reply to them. It would also be better if you think about what I said because there is a good chance the ideas I am presenting are something you have never heard before. My point of view is quite unique.
 
  • #22
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Still waiting....

Are you all too afraid to touch this one?
If science is based on experiment and experiment is based on observation and observation is based on perception how do you even know your perceptions are correct? Can you prove this experimentally? If not then the foundation of phyics must be abandoned. If so how can you establish that perceptions, which are the foundation of experiemental verification, are vefified by experiemnt. How would you know this experiment is valid?
 
  • #23
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Originally posted by protonman
\ It would also be better if you think about what I said because there is a good chance the ideas I am presenting are something you have never heard before. My point of view is quite unique.
Where have you been all of our lives?...
 
  • #24
Nereid
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Originally posted by protonman
If something's description is in accordance with the how the object actually exists.
That takes us back one step ... how do you determine 'how the object actually exists' ? (the 'actual existance of the object'?)

And if your determination is to be anything more than something in your own mind, how can I (or Russ, or SelfAdjoint, or Mentat, or marcus, or Greene, or Hawking, ... ) make that same determination?
 
  • #25
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Originally posted by Nereid
That takes us back one step ... how do you determine 'how the object actually exists' ? (the 'actual existance of the object'?)

And if your determination is to be anything more than something in your own mind, how can I (or Russ, or SelfAdjoint, or Mentat, or marcus, or Greene, or Hawking, ... ) make that same determination?
If something exists it is an object of a valid perception.
 

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