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A Request to the Physicists Among Us

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#76 llanitedave

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Posted 01 April 2013 - 03:55 PM

The "what happened before the Big Bang" question is functionally identical to "what's outside the Universe", since at least in a spacetime context, time is as much a creation of the Big Bang as space is.

Although it is strange, when you think about it, that there doesn't seem to be any expansion of time in the universe along with the space. Why are three new dimensions constantly being expanded, but not the fourth dimension?

#77 Otto Piechowski

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Posted 01 April 2013 - 04:51 PM

I have read the words "expansion" and "expand" and "expanding" to refer to the activity of the universe after the Big Bang.

In what sense does the universe expand? is expanding? undergoing expansion?

The word expand means to grow in size as measured against some standard measure; the measuring tape, the size of the theatre seat...all of these are things outside the thing which is expanding.

Yet, we say there is no place outside the universe into which the universe expanded or could have expanded. Thus, my question, in what sense do we say the universe expands? is expanding? underwent expansion?

Otto

#78 EJN

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Posted 01 April 2013 - 05:08 PM

What you refer to is an extrinsic frame of reference, where something
is measured against external objects. The mathematics of relativity describes
"intrinsic" expansion, that is without reference to anything external.

That the expansion is taking place is known because of the redshifting of
distance objects, the light being "stretched" so to speak. In relativity
light defines the null geodesic.

I posted this in the "Where is the expanding universe going" thread which
perhaps you should read.

In the geometry of spacetime, the shortest distance between 2 points is defined
by the path of light (or any electromagnetic wave). This is called the null,
or lightlike geodesic.

Consider 2 points, A & B, in a static spacetime. Light traveling from point A
to point B defines the geodesic connecting the points. In the time the light
travels from A to B, it undergoes X cycles of the light wave (if I recall the
frequency of visible light is in the hundreds of terahertz).

Now consider points A & B in an *expanding* spacetime manifold. Initially,
the separation is the same as above. As light travels from A to B, the manifold
expands. When the light reaches point B, it will have undergone exactly the
same number of wave cycles as in the above example above. How? As the manifold
expands the wavelength increases, so the frequency decreases. When light
arrives at point B, it has a longer wavelength and so appears to be redshifted.

From the point of reference of the light wave, it has undergone exactly the same
same number of wave cycles in both cases, no "new" space has been traversed.

As is often the case in physics, what can easily be expressed in mathematics
is difficult to explain using just words.



My alternate answer to where the expanding universe is going is that it
is going to some place out in the sun, right down Highway 61.



#79 Otto Piechowski

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Posted 01 April 2013 - 06:01 PM

Since there is no external referent against which the expansion is measured, how do we know from the red-shift evidence that the universe is not, instead, going through some process of universal-diminution (everything receding from everything else and reducing in size)?

#80 Joad

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Posted 01 April 2013 - 06:13 PM

This is what I meant when I said that modern physics, at both the micro and macro level, is not susceptible to a logic based in natural languages. Our natural languages are adapted to the scale in which we evolved, and are adequate to it. Applying them to the other scales doesn't lead to anything.

#81 Otto Piechowski

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Posted 01 April 2013 - 06:15 PM

Joad,

Thank you.

Are you saying that the expansion of the universe cannot be described in normal (non-mathematical) language?

Otto

#82 Joad

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Posted 01 April 2013 - 06:42 PM

The word "expansion" gets us into trouble. It is better to go over what current physics says (which, of course, may turn out to be mistaken).

A lot has to do with quasars, whose red shifts (mathematically calculable) indicate that they are really really far away from us and moving even further away.

Then comes the Big Bang theory (which appears to be holding up in the face of new evidence). If the universe erupted from a singularity, and quasars are now billions of light years apart, well, you see what conclusions that leads to.

This is all pretty new. From Aristotle to Einstein a lot of bright people thought the universe was in a steady state.

#83 CounterWeight

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Posted 01 April 2013 - 06:50 PM

Another good book I want to recommend. I've used it as a basis for lectures on your question, and I always highly recommend it, in ways one of the least mathmatistic for the absolute gems it contains.

"Geometry, Relativity, and the Fourth Dimesion" by R. Rucker.

I have to admit I'm confused Otto about what you're after. Enuf is enuf. It's possible to ask questions effortlessly without the least effort to discover the multitude of 'low hanging fruit'. You are getting some great answeres but seem uninterested in expending the least effort to even take the time any reasonable person might do to 'discover' the true terrain of any of this. I and others are spending time to try and steer you in the directions to help understand the questions you are asking (NOT THE ANSWERS, THE QUESTIONS) but YOU need to take some time and effort to do at least the very basic legwork any reasonable person might do that had a genuine interest in the many topics you seem to traverse without taking the least time to fathom even in a very shallow the implications and directions the previous question generates?

For anyone really interested there is a significant amount out there on the web and paper composed specifically for you. IMO it takes very little effort to wade into the shallow end of the pool, but you have to actually be interested.

For that reason, I'll let rest any more input here by me. I hope you find what you are after, but more importantly learn to respect the effort others have spent in their respective diciplines to try and answer your questions. More importantly that you put some effort into it.

What concerns me is you might 'parrot' some of it without taking the effort to understand it, research it, make some effort. It's that sort of thing that confuses the heck out of casual bystanders, and leads to some less than desirable opinions about modern physics and mathematics, logic and philosophy. I see this as a recurring theme in this endless series of questions.

This last one about 'space' sort makes my point. It's a personal choice, but I don't and have never tutored anyone who will not take their own time and effort. Asking continual questions IMO takes no talent whatsoever. Asking a good question shows that at least the effort I and others are putting out is being respected and returned in kind.

So my request to the Otto among us is to please slow down and try and spend at least some minor effort in understanding the questions you are asking to us physics folks, reward us with that. How can anyone possibly answer when IMO you don't understand the question you ask, dont want to take the least time and effort to understand it yourself before asking.

Again best of luck to you.

#84 Jarad

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Posted 01 April 2013 - 06:51 PM

Since there is no external referent against which the expansion is measured, how do we know from the red-shift evidence that the universe is not, instead, going through some process of universal-diminution (everything receding from everything else and reducing in size)?

Actually, that is a good question. DeSitter has pointed out several times here in the past that you could in fact solve the math just as well by positing that we (and everything else in the universe) are shrinking.

Jarad

#85 Otto Piechowski

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Posted 01 April 2013 - 07:33 PM

Thank you Jarad.


I see this computer in front of me. It appears to be a solid object. As does the coffee cup to the side of it and as did the banana some few minutes ago. They all appear solid. If I were talking to a child I would just say, they are solid.

I have learned that these objects are composed of particles which cannot be sensed by the human senses; they are too light in weight, smaller than wavelengths of light to distinguish them, etc.

Further, I have learned that these particles are not particles in the sense of particles of dust or shot-gun shot or grains of sand, but bundles of energy existing in some type of quasi-real state/probabilistic state and whose essence/nature is defined by the field in which they exist.

In short, the computer/cup/banana only appear solid to our senses created to see them as such by the evolutionary processes within which we have been formed. But, In reality, there are in some type of state/composition/particalisation/field-enshrinement which is not describable by the ordinary-world-word, solid. In short, human speech, adapted to the world in which we operate/live on a daily basis of typing, drinking, eating, is not well suited to describing the realities as we are beginning to understand them.


I wonder if the same is true of the universe, in general, and of universal expansion in particular. I wonder if the words we use in human (non-mathematical) are as inadequate to describing these macro-cosmic things/events as they are of the micro-cosmic events things. More specifically, I wonder to just-what-degree our normal human (non-mathematical) speech is inadequate to the task of communicating an accurate description of these macrocosmic things/events/realities?

#86 Otto Piechowski

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Posted 01 April 2013 - 07:42 PM

I think there are three separate questions I am asking:

1. Are the ways we sense things in the everyday world not correlatively useful for understanding (creating useful metaphors for explaining) subatomic reality? macro-cosmic reality?

2. Are the words we use to describe how we sense things in the everyday world not useful for describing subatomic realities? macro-cosmic reality?

3. Do we need to bracket the phenomenological issue that whatever and however I sense things in the everyday world, the "sense-image" of which I am aware is "in-here" (in the brain); and not so-much a presentation of the thing "out-there" (outside the body sensing them).


Trained in philosophy, I really enjoy these type of questions. Having said that, and standing by that statement, I must also say that I suspect (would bet) that (1) there is universal expansion as indicated by red-shift data, (2) that everything you all say about the subatomic nature of reality is correct, and (3) that the images which appear in my mind are good objective representations of the objects as they exist outside of my body.

#87 ColoHank

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Posted 02 April 2013 - 10:36 AM

The University of Kentucky offers majors in astronomy and astrophysics. Anyone with an interest in this topic who lives in the Lexington area might audit a course or two, develop some relationships with faculty and students, and find some answers there.

#88 llanitedave

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Posted 02 April 2013 - 01:04 PM

Another good book I want to recommend. I've used it as a basis for lectures on your question, and I always highly recommend it, in ways one of the least mathmatistic for the absolute gems it contains.

"Geometry, Relativity, and the Fourth Dimesion" by R. Rucker.

I have to admit I'm confused Otto about what you're after. Enuf is enuf. It's possible to ask questions effortlessly without the least effort to discover the multitude of 'low hanging fruit'. You are getting some great answeres but seem uninterested in expending the least effort to even take the time any reasonable person might do to 'discover' the true terrain of any of this. I and others are spending time to try and steer you in the directions to help understand the questions you are asking (NOT THE ANSWERS, THE QUESTIONS) but YOU need to take some time and effort to do at least the very basic legwork any reasonable person might do that had a genuine interest in the many topics you seem to traverse without taking the least time to fathom even in a very shallow the implications and directions the previous question generates?

For anyone really interested there is a significant amount out there on the web and paper composed specifically for you. IMO it takes very little effort to wade into the shallow end of the pool, but you have to actually be interested.

For that reason, I'll let rest any more input here by me. I hope you find what you are after, but more importantly learn to respect the effort others have spent in their respective diciplines to try and answer your questions. More importantly that you put some effort into it.

What concerns me is you might 'parrot' some of it without taking the effort to understand it, research it, make some effort. It's that sort of thing that confuses the heck out of casual bystanders, and leads to some less than desirable opinions about modern physics and mathematics, logic and philosophy. I see this as a recurring theme in this endless series of questions.

This last one about 'space' sort makes my point. It's a personal choice, but I don't and have never tutored anyone who will not take their own time and effort. Asking continual questions IMO takes no talent whatsoever. Asking a good question shows that at least the effort I and others are putting out is being respected and returned in kind.

So my request to the Otto among us is to please slow down and try and spend at least some minor effort in understanding the questions you are asking to us physics folks, reward us with that. How can anyone possibly answer when IMO you don't understand the question you ask, dont want to take the least time and effort to understand it yourself before asking.

Again best of luck to you.


As long as we're recommending books...

Not an astronomy book, but can be classified as a philosophy book:

Karl Popper's Conjectures and Refutations. Most of the questions we've been getting here are only superficially about astronomy and more about the deeper approach to thinking about how to distinguish scientific ideas from unscientific ones. Popper has his share of critics and detractors, but I have yet to find those criticisms compelling. I have a few quibbles with some of his ideas, notably about the relationship between theory and observation, but those quibbles are minor and don't detract from his fundamental argument.
There is no better guide that I have read for understanding how to think critically about the world around us.

It's dense reading -- it took me about a year to slog through it, but it's worth the effort. And as CounterWeight has pointed out above, understanding this stuff really does require significant effort.

If your brain doesn't hurt, you aren't thinking hard enough.

Get Popper. Read it. Make notes in the margins. Feel free to disagree in those margins, but detail your disagreement.

You'll be a better person for it.

#89 Otto Piechowski

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Posted 02 April 2013 - 01:31 PM

Jim and Hank(Henry?)'s comments are appreciated. Your suggestions to me are humbling. As always, the same applies to Dave's comments. Though I might not act on the fine ideas you suggest, they are none the less appreciated by me. They are humbling in the good senses that they give me an inkling of the things each of you understand and which I do not, and in terms of my neediness if I would ever choose to get some scientific/mathematical appreciation of what you know.

For now, my interest lies on the question of how well subatomic and cosmic realities, as revealed through relativity theory and quantum physics; how well can these be accurately described in human (non-mathematical) speech. I would really like to hear/read your opinion in response to that question.

Hank (Henry?) suggested I avail myself of the astronomy courses over at the University of Kentucky. Though not the actual scientific classes, on a regular basis the physics/astronomy department in conjunction with the Blue Grass Astronomy Club provides session on current issues in astrophysics. Most of the people attending have little or no background in tensor algebra, vector calculus, relativity, or quantum physics, etc. The cosmic and subatomic realities being described are described in human (non-mathematical) speech suited for such an audience.

To what degree can human (non-mathematical) speech accurately display the most important and current facts about sub-atomic and cosmic realities? I would appreciate hearing your response to this question.

Thank you.

Otto

#90 llanitedave

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Posted 02 April 2013 - 01:34 PM

To what degree can human (non-mathematical) speech accurately display the most important and current facts about sub-atomic and cosmic realities? I would appreciate hearing your response to this question.


Do you want a numeric measurement of the degree of accuracy? ;)

#91 Otto Piechowski

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Posted 02 April 2013 - 03:29 PM

That was both funny and insightful. How imprecise ordinary speech is!

When I had learned about the idea of quantum indeterminacy, I asked around for an example of what was meant by that. A student told me a high school science teacher had told him that quantum indeterminacy was like being told that there was a black balloon inflated-with-a-lighter-than-air-gas hovering somewhere in a room. The room was totally dark; no illumination at all. One's assigned task was to walk into the room and determine the location of the balloon by touch alone.

The problem, of course, was that the moment one touched the balloon, that this act of "observation" changed the location of the balloon in the room. Thus, this metaphor gave a real-world example of quantum indeterminacy; how the act of observing a parameter changes that parameter.


A few weeks later I was talking with an high school physics teacher over lunch about quantum physics. This physics teacher had had mathematics based courses in quantum physics. I asked her opinion of the black balloon metaphor. She immediately and definitely said that experiences from the real world of ordinary human sense perceptions could never be used as metaphors to provide an accurate description of quantum phenomena.

Was she, the physics teacher, correct?


If she is correct, does her statement apply to relativistic phenomena as well. For example, I remember learning that relativistic time dilation could be described in terms of two people standing under a clock. At the exact moment of noon, one moves away from the clock at the speed of light. Fifteen minutes later, both are asked the time on the clock. The person standing under the clock says it is 12:15 PM. The person moving away from the clock is asked the same, and looks back at the clock through a telescope and says, "It says noon." The reason it says noon is because the most current light-iinformation of the clock available to him is the light which left at the same speed he did, fifteen minutes ago at noon exactly. So, if real world metaphors cannot be trusted when dealing with quantum phenomena; can they be trusted when used to describe relativistic phenomena?

Otto

#92 Joad

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Posted 02 April 2013 - 03:32 PM

It depends upon your frame of reference.

#93 Mister T

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Posted 02 April 2013 - 03:39 PM

I got this one Dave!

Otto: 42% :graduate:

#94 Otto Piechowski

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Posted 02 April 2013 - 05:39 PM

When I had learned about the idea of quantum indeterminacy, I asked around for an example of what was meant by that. A student told me a high school science teacher had told him that quantum indeterminacy was like being told that there was a black balloon inflated-with-a-lighter-than-air-gas hovering somewhere in a room. The room was totally dark; no illumination at all. One's assigned task was to walk into the room and determine the location of the balloon by touch alone.

The problem, of course, was that the moment one touched the balloon, that this act of "observation" changed the location of the balloon in the room. Thus, this metaphor gave a real-world example of quantum indeterminacy; how the act of observing a parameter changes that parameter.


A few weeks later I was talking with an high school physics teacher over lunch about quantum physics. This physics teacher had had mathematics based courses in quantum physics. I asked her opinion of the black balloon metaphor. She immediately and definitely said that experiences from the real world of ordinary human sense perceptions could never be used as metaphors to provide an accurate description of quantum phenomena.

Was she, the physics teacher, correct?

#95 EJN

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Posted 02 April 2013 - 06:10 PM

Was she, the physics teacher, correct?

Yes

If she is correct, does her statement apply to relativistic phenomena as well.

No

#96 llanitedave

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Posted 02 April 2013 - 06:15 PM

She was correct. Your balloon demonstration may have been conceptually useful, and it seems kind of cool to me, but it wasn't "accurate" in any predictively useful sense. It's like the baking soda volcano often used in elementary school demonstrations. It may help with a general vague sense of what a volcano does, but its not really something you can use.

Quantum mechanics doesn't really mean much unless you are using it quantitatively. You simply can't do anything with it.

#97 Otto Piechowski

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Posted 02 April 2013 - 06:17 PM

Dave,....that baking soda volcano metaphor makes really clear to me the inadequacies of which the teacher was speaking!!!

EJN, I am fascinated by your "no" to the relativity one. In light of Dave's comment which followed yours, the clock-metaphor is not like the baking-soda-volcano, but actually getting at what relativity is?

Dave...can you say a bit more about what you meant by "you can't do anything with it"? (Perhaps, was the full idea "you can't do anything with it if you don't use it quantitatively"?)

#98 EJN

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Posted 02 April 2013 - 06:26 PM

EJN, I am fascinated by your "no" to the relativity one. In light of Dave's comment which followed yours, the clock-metaphor is not like the baking-soda-volcano, but actually getting at what relativity is?


The only problem with the clock metaphor is that you couldn't actually
travel at the speed of light, but you could (in theory) travel at 99.999999%
of the speed of light, and the clock would read 12:00:00.001
(decimal places not accurate, but you get the picture). Of course
the acceleration involved to actually do that would squash you like
a bug.

#99 Otto Piechowski

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Posted 02 April 2013 - 06:35 PM

Thank you.






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