Relativity - Oh dear, here we go again!
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sol invictus
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You find that obvious? Really? I don't.
It's becoming apparent to me from reading this forum that many lay people have a rather odd idea about reality and its relationship to science and scientific theories. When we do experiments, we are testing our theories about reality. Sometimes the experiment agrees with the theory, sometimes it doesn't (and then we know the theory needs to be modified). But we will never be able to say that a theory *is* reality - that's not a scientific statement. And so we will never be able to say (scientifically at least) what reality is or is not.
Modern theories of physics are based on point particles (except for string theory, but lets leave that out for a moment). Those theories provide an incredibly precise description of reality, and there's little or no evidence that they need to be modified. Quite the contrary, really. So who are you to say that that description is "obviously" wrong and a fantasy? Are you omniscient?
Well my purpose is an attempt to evaluate the validity of the theory of relativity from a realistic perspective, not theoretical. When I evaluate the validity of religion I don’t do so on the premise that the bible is valid.
Ziggurat
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The link is to a page first, and then a reference to the post within that page (the bit after the # mark). If the post isn't on the page in question, then yeah, I guess it won't work. I'm working with 40 posts per page - I wasn't even aware that changing that was an option.
So you’re saying that a thing that has no width, length or breadth can have actual, factual, real existence? In other words, nothing is something?
RecoveringYuppy
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Can you provide some evidence that the electron has width, length or breadth?
How is anyone supposed to discuss reality usefully without employing concepts from the scientific theories that are the most helpful in understanding it?
You might as well argue that, in discussing reality, we shouldn't use any words at all, because no word is really part of nature---they were all just made up by people.
Can you provide some evidence that the electron has actual existence? (not theoretical).
Ziggurat
Penultimate Amazing
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Aren't you rather staring at overwhelming evidence right this second?
The electron's existence is rather well-established, from Milikan's oil drop experiment to beta radiation to cathode ray tubes (you know, as in televisions). Modern technology depends upon electrons.
Feynman on proposing and evaluating laws of physics:
http://www.youtube.com/watch?v=ozF5Cwbt6RY
http://www.youtube.com/watch?v=d1ZtRN-iGdQ
The video clips are very short, but very important. Watch them a few times, and think about them. The method they describe may seem backwards, but it is how science works. Reality is too complicated to be understood in any other way.
This is getting quite philosophical.
Perhaps you could give us an example of something that, in your opinion, has actual existence, as well as what you consider to be the evidence for its existence? Just so we know what sort of evidence you'd consider relevant to the question of the actual existence of electrons.
Fredrik
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These are some of the reasons:
1. There's an exact definition of what "points" are.
2. Having "points" in a theory doesn't make it impossible to use the theory to make predictions.
3. Having "points" in a theory doesn't make the theory's assumptions more complicated than what it's intended to describe.
4. Having "points" in a theory doesn't make it contradict itself.
Do you think you can say these things about gods or invisible unicorns?
Fredrik
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The word "electron" only has an exact definition in the theory of quantum electrodynamics, which is just an approximate description of some aspects of reality. (Extremely accurate, but still approximate). So in a way it makes sense to say that its existence is theoretical. (The theoretical electron is well-defined but exists only in the theory. The real electron obviously exists, but we can't define exactly what a real electron is, so when we say that "it" exists, it's not entirely clear what the word "it" refers to).
You could of course say the same thing about anything, so if electrons don't have an actual existence, then nothing else does either (except your own thoughts I suppose).
Physicists understand that, so when they get a question about a real electron, they either give you an approximate answer about a real electron, or an exact answer about a theoretical electron. You will never get an exact answer about a real electron, at least not until someone finds a complete theory of everything, and I don't think that's ever going to happen.
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Paulhoff
You can't expect perfection.
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Gee, I don't know, how about the CRT you may be using for a monitor and/or TV, what do you think is hitting phosphorus on the inside of the glass to make it glow, wishful thinking.
Paul
Fredrik
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But wouldn't it be easier to evaluate Christianity if you actually knew what the bible says? You seem determined to evaluate relativity without learning anything about it.
Fredrik
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The biggest obstacle to your understanding of physics, except for your attitude, is your poor understanding of what a theory is and how theories are used.
One way to discuss reality is to discuss the theories that describe it approximately. The advantage of this is that all the concepts we're using are well-defined. The disadvantage is that we're really describing a fictional universe that just resembles our own.
The other way is to try to discuss reality directly. The advantage is that we're talking about our own universe. The disadvantage is that the words we use not well-defined, so the things we say don't have an exact meaning. Sometimes we can't even be sure that we're talking about the same thing.
We had this discussion in several threads already. Because there is no governing body, no real authority when it comes to science, much less terminology, there is real confusion over semantic matters. The lower down on the food chain somebody is, the more they seem to think they can define everything.
I had some nuts trying to tell me there are no laws of physics, that no theory is ever proved, and the reason scientist still use terms like laws or principles is because they didn't know any better way back when.
I'm not kidding. They also confused theory, which isn't hard. It has at least seven different meanings, and sometimes is used instead of hypothesis, further clouding the quantum interactions.
I had some nuts trying to tell me there are no laws of physics, that no theory is ever proved, and the reason scientist still use terms like laws or principles is because they didn't know any better way back when.
I'm not kidding. They also confused theory, which isn't hard. It has at least seven different meanings, and sometimes is used instead of hypothesis, further clouding the quantum interactions.