elfmotat

When he's talking about information, he's speaking of entropy which is a measure of the system's hidden information (information which has been "course-grained" away). Total information, if you can keep track of it, is always conserved. Entropy is not conserved. The amount of "stuff" present doesn't need to change for the entropy of the "stuff" to increase. For example, take the picture below:

At the top, two types of gas molecules are present in a box but are separated by a barrier. At the bottom, the barrier has been removed and the gasses have been allowed to spread out and mix together. The bottom box's entropy is greater than the top box's, just from allowing the gasses to mix.

In geometric units (c=G=1), the area of the event horizon (of a non-rotating BH) is [math]A=16 \pi M^2[/math], and its entropy is [math]S = A/4 = 4 \pi M^2[/math]. If we were to assume a perfect collision between two black holes of mass [math]m_1[/math] and [math]m_2[/math], where no energy is lost, the new combined BH would have a mass [math]M=m_1 + m_2[/math]. Its entropy would therefore be [math] S = 4 \pi (m_1^2 + m_2^2 + 2 m_1 m_2)[/math], whereas the entropy of each BH before collision would be [math]S_1 = 4 \pi m_1^2[/math] and [math]S_2 = 4 \pi m_2^2[/math]. We therefore see that [math]S > S_1+S_2[/math]. The entropy generated from their combination is [math]S_{gen} = 8 \pi m_1 m_2[/math].

[ot]

Welcome back! Long time no post. Hope the self-schooling is still progressing - it was already pretty amazing.

[/ot]

Hi! Unfortunately I've been pretty busy working, working on my degree, and playing music to get much physics self-study done for a while. I'm looking to get back into it, so hopefully I'm not too rusty.

Your intuitions are good. Newtonian gravity can be derived from GR with the assumptions that: 1) gravity is weak, and 2) matter is non-relativistic. In particular you assume that the metric is nearly flat, different only by a small amount [math]|h|\ll 1[/math]:

[math]g_{\mu \nu} = \eta_{\mu \nu} + h_{\mu \nu}[/math]

You plug this into the Einstein Field Equations (making use of the fact that matter is non-relativistic so all but the 00-component of the Stress-Energy Tensor will be zero), and you're left with the differential equation:

[math]\nabla^2 h_{00} = -8 \pi G \frac{\rho_E}{c^2} = -8 \pi G \rho_M[/math]

where [math]\rho_E[/math] is energy density, which we can replace with mass density [math]\rho_M[/math] because matter is non-relativistic. Note the similarity to the Poisson Equation for Newtonian gravity:

[math]\nabla^2 \Phi = 4 \pi G \rho_M[/math]

for gravitational potential [math]\Phi[/math]. Indeed we can simply identify [math]h_{00} = -2 \Phi[/math] and they are equivalent. So using only the assumptions that gravity is weak and matter does not move fast, we obtain the fundamental equation of Newtonian gravity from GR. (The inverse-square law can be derived from Poisson's equation.)

AFAIK your suggestion to replace the denominator of the inverse-square law with the interval (proper distance perhaps?) does not really have any meaningful interpretation.

The issue here is that electron and wave are separate physical entities and as a result an electron has to be orbiting in the atom. The psi-function represent some physical field (standing wave) that interacts with the electron

Oh, so you're arguing for a particular interpretation of QM? This sounds a lot like the De Broglie-Bohm interpretation. Unfortunately that's probably not going to be very useful. There is no test you can do to distinguish which interpretation is 'correct.' They're called interpretations for a reason!

 

I mean, really, he doesn't have to acknowledge that time is "actually" doing anything, so long as he acknowledges that it behaves as if it's following the rules laid out in relativity.

I agree. My point was that "time 'actually' being effected" is a vague and ill-defined concept.

Also, what exactly is the difference between "two observers observing time differently," and "time 'actually' being effected"? What test should we contuct to determine if time has actually been effected if measuring differences with clocks is not sufficient? All 'clocks' are effected in the same way, including biological processes. If it were otherwise, we'd be able to measure time differences between different types of nearby comoving clocks, which is not what we observe. (Also, this would provide a way to measure 'absolute' velocity, violating the Principle of Relativity!) In what way does this not constitute time being effected?

I'm not sure how to convince your father that time and space are interwoven other than to point him to the math. The math interweaves them, and the math agrees with observation and experiment.

You should point out that:

1) Human brains evolved to intuitively understand slow moving (compared to c), macroscopic, gravitationally weak phenomena. It should not be surprising that we fail to intuitively understand fast moving, cosmic scale (or micro scale), gravitationally strong phenomena. Common sense is not useful in these regimes, and will lead you down the wrong path more often than not.

2) That time dilation's existence is not under debate. Relativity is one of the best tested fields in science. As an everyday example, GPS systems must account for time dilation due to both motion and gravitation. They would drift off-mark significantly without relativity.

Oh no, we have gone much past linear algebra, we are doing limits and derivatives, so i am learning the basics of calculus in my pre-calculus class, We have also gone over vectors so that should help. But in Carroll's notes it talks about rotating the axis, and taking their primes, that is some deep calculus i have not learnt yet, those things are going to be the things that trouble me.

Most people take a linear algebra course after taking multi-variable calculus. Regardless, much of Special Relativity can be learned with basic algebra and the Pythagorean Theorem. There are many good explanations of the 'light-clock' thought experiment floating around, which is a good starting point.

So, just to be clear, both mass and energy are properties of a system and inexorably linked.

Yet one is frame dependent and the other is not.

 

Is this because of what we choose to define as 'mass' ?

Yes. There are a number of definitions of 'mass,' each with different properties, some of which are very rarely used, and some which aren't very useful. Just to name a few, in SR there's rest mass, relativistic mass, transverse and longitudinal mass. In GR things get even more complicated when trying to come up with definitions of non-local mass. As a result there are the Komar, ADM, and Bondi definitions, among others.

https://en.wikipedia.org/wiki/Mass_in_special_relativity

https://en.wikipedia.org/wiki/Mass_in_general_relativity

Usually when people talk about 'mass,' what they are referring to is rest mass, and usually the context will make clear to what one is referring.

Note that multiple definitions of a quantity is not particularly unusual. For example, in SR there's the coordinate acceleration, which is defined as [math]a^i := \frac{d^2 x^i}{dt^2}[/math]. This vector is not invariant under Lorentz boosts (which is not surprising because it is explicitly coordinate-dependent). There's also the four-acceleration: [math]a^\mu := \frac{d^2 x^\mu}{d \tau^2}[/math]. This vector is Lorentz-invariant, in that its magnitude does not change under boosts and corresponds to proper acceleration (i.e. the acceleration it actually 'feels', or that an accelerometer would actually read). In GR the four-acceleration is redefined as: [math]a^\mu := \frac{d x^\nu}{d \tau} \nabla_\nu \frac{d x^\mu}{d \tau} = \frac{d^2 x^\mu}{d \tau^2} + \Gamma^\mu_{\lambda \sigma} \frac{d x^\lambda}{d \tau} \frac{d x^\sigma}{d \tau}[/math]. This vector is invariant under all diffeomorphisms in that its magnitude corresponds to proper acceleration.

Thanks!

It's an absolute or constant parameter in this scenario?

I'm not sure what you're asking. Mass remains constant under a change in reference frame, if that's what you mean.

Special or General Relativity? If you're already familiar with SR and want to move onto GR then I agree with ajb's recommendation. If you're new to it I recommend reading Spacetime Physics by Taylor and Wheeler. Carroll's full GR textbook is excellent as well.

Mass isn't determined by compression.

At least not in the manner you are implying. For example if a star collapses to a black hole. It's mass doesn't change. The only thing that changes is the radius.

He's positing that mass is some functional of the stress (tension/compression) of the aether field... which seems immediately false, unless there's some way to get discrete mass values for elementary particles in this manner.

 

Some thoughts to go along with this:

 

k starts out at 0 when there is no compression because mass is 0 and inceases from there

Having to act through distance and time may be related to how charge and gravity drop off at r^2

For the electron instead of hooke's law newtons law F=ma might apply because if it is a spherical standing wave it is undergoing constant acceleration.

You seem to be describing some sort of field whose properties determine mass. If you could formalize this it would help narrow down exactly what you're talking about, and whether or not the idea is self-consistent and consistent with observation.

Personally I find the qeust for grand unified theories boring.

If it it ends up showing there is only one agent at work in the whole universe then there is only one thing left for that agent to interact with - itself.

I much prefer the universe of a multiplicity of agents and a myriad of interactions.

I'm not sure how this is a problem. Any ToE is going to have broken symmetries, resulting in interacting components. For example electroweak symmetry -- at low energies the symmetry is broken resulting in EM and the weak force. Is the universe more 'boring' because we know they unify at some level?

See my previous post.

Okay:

 

We'll get to those eventually but don't you have a single thought or feeling (besides it being incomplete) on what I've said before.

 

This includes:

 

The wave explanation of the photoelectric effect

There is no wave-only explanation of the photoelectric effect (unless you count QED as being 'wave-only'). That's why it's a well-known effect! It forced physics to adopt a particle approach.

Mass as the measure of compression

What does this mean? Mass isn't a measure of compression in any model I'm aware of. Why do you think this should be the case? And compression of what? The 'medium' you keep referring to? Again, you haven't defined this well enough for us to comment.

The medium being infinite, continuous, and compressible

The first two assumptions seem reasonable for any 'medium' that's supposed to fill space, but I don't see why you're assuming it should be compressible. How does it get compressed? How does it evolve? What are the dynamics of this medium?

The finite speed of light as the reason behind why absolute consistency is never achieved

What is "absolute consistency" and how does a finite speed of light imply it?

Electrons are said to be spherical standing waves.

Not always! Not even most of the time!

Why waves have a finite speed is still troubling. I think infinite is just unreasonable but why it should be a certain value is concerning. Same with the size of the electron, etc. Planck's constant might have some sort of connection.

These are parameters that cannot be explained by any current theory. How does your model seek to explain them?

I was also thinking Planck's constant might be related to Hooke's law, but again really need comments!

That's interesting. Could you expand on this?

If you think I'm crazy or just flat out wrong so be it.

I think you're trying to come up with a physical 'theory' without really understanding what a physical theory is, and without having all the facts.

I give you permission not to comment.

How very generous.

 

Let me rephrase: It has to be something.

Why? The term "empty space" implies that there's space (i.e. not zero distance between all objects) and that it's empty. You can define distances in space without needing any matter, or any type of "medium" as you call it.

And yet I hear all the time that physics is incomplete. If your explanations can explain the medium (which this whole thread is supposed to be about) then list its properties so I can be on my way.

Your proposed "medium" is not well-defined, and it has no explanatory power, theoretical basis, or evidence for its existence. Physics is incomplete, for sure, but that doesn't mean making up nonsense is a good way to fill in the gaps.

How do they have those properties, or better put how can those properties be explained?

As of yet many of them cannot be. There are many tunable parameters in the Standard Model that cannot at present be explained by any deeper theory. (Because we don't have a deeper theory yet!)

Long way off before a mathematical model.

I'm curious how you're able to do any physics without math.

Part of the reason why I'm here. You could either help or offer criticism. But saying I can't do it or it can't be done because of this or that doesn't do much.

It's not entirely clear what you're trying to do because you haven't expressed or defined any of the concepts you're discussing to any satisfying degree. You also appear to hold a number of misconceptions. We're not clear on how to help, because frankly none of us know what you're talking about!

Given two unit quaternions, [math]p[/math] and [math]q[/math], you can always find another unit quaternion [math]r[/math] such that [math]rq=p[/math] which represents the amount you need to move [math]q[/math] to match [math]p[/math]. Solving for [math]r[/math] gives:

[math]r = pq^{-1} = p~ \textup{Conj}(q)[/math]

The angle between [math]p[/math] and [math]q[/math] is the angle of [math]r[/math], which is given by:

[math]\alpha =2 \textup{cos}^{-1}(\textup{Re}(r )) =2 \textup{cos}^{-1}(\textup{Re}(p~ \textup{Conj}(q)))[/math]

I must think that? Is that a prerequisite for thinking that our cultures have more of an effect on women's career choice than any kind of biological preference? Where did my right/wrong judgment happen, in your opinion?

I was under the impression that you saw the gap as a problem to be fixed. "Right" or "wrong" choices being those that do/don't close the gap.

You put forth the argument that I'm insulting the agency of women by claiming they're affected by attempts to dissuade them from certain career choices.

It implies they're too weak to think and decide for themselves. Maybe you're right, societal influences play a particularly massive factor. I just don't think we're that easily programmable, especially when it comes to important life decisions.

Do you have any evidence of systemic attempts to dissuade women from entering STEM?

If I were to make similar claims of unjust manipulation about people being affected by internet harassment, would you assume I'm trying to insult them?

That's a bad analogy. Getting bad feelings from being harassed is not the same as letting societal pressures control your life decisions. The former can't be helped, as it is not their choice to be harassed. The latter can be helped -- it is entirely within their control.

"They're big girls, they can take care of themselves, you're insulting them to think they could be swayed in their career choice by their society."

Swayed? Sure. So magnificently manipulated by the international community that huge cross-cultural gender gaps emerge and stabilize? Seems unlikely.

No, the advertising part was analogy, trying to equate the subtle, constant aspects of both advertising and societal pressures. Sorry I wasn't clear on that.

Okay. I'm still not convinced by this though. How would you even test the "subtle societal pressures plays large role in career choice" hypothesis?

Again, I've been unclear. This was not personal. It's your argument I was talking about, that it seems to need women to be biologically disposed to certain professions, or at least much more so than they're affected by their societies.

It is a fact that males and females are biologically predisposed to have at least somewhat different interests (see post #2). It is my opinion that this accounts for different career choices. It is my opinion that this probably plays a larger role in the STEM gender gap than culture, given that it is a stable cross-cultural phenomenon. My arguments are tailored to reflect those opinions.

It seemed to help minorities when we agreed not to treat them differently with respect to employment and housing. Many people now have a broader range of freedom to make life decisions because they can factor a mandatory lack of prejudice into the equation. I offer this as evidence that it might work with women in STEM.

What careers, in the developed world, are still restricted to men? What field could I get a job in as a man but not as a woman? We've had equal opportunity laws for decades. I see absolutely zero evidence for systematic discrimination of this kind.

But are you also saying that men should be compensated more on average because more men die on average while working? Is this the risk you're talking about, besides the obvious stuff like "skyscraper construction worker"?

No. For example, Alaskan crab fishermen should be paid more than a common carp fisherman. Hazard pay. That men are more likely to take these types of dangerous jobs is irrelevant to whether they should pay more.

Apparently you think that hiring managers and recruiters play no role in this process. Fascinating.

Do hiring managers also choose your college major for you? The same gap is reflected there.

Hey, there's our friend Mr.Strawman again. He really is becoming a regular around these parts. Perhaps we should reserve him a seat.

You disingenuously removed the next part, where I asked Phi to explain what is wrong with my reasoning. It's now considered a strawman to ask what is erroneous about an argument?

Suddenly, I have an assumed lack of respect for women's agency, because I think many societies don't treat women equally in the workplace? This argument reminds me of the "if you don't support the war, you must hate our soldiers" fallacy.

Women decide for themselves (at least in modern western countries) what careers they go into. Obviously you must think they choose wrong en masse, resulting in the STEM gap.

What, exactly, is incorrect about the above? Do you agree that women decide on their careers for themselves (usually, at least)? Do you disagree with those choices at a systemic level? Do you think you know better? Do you agree that that sounds a bit disrespectful?

You attempt to put down any kind of brainwashing as absurd. Personally, I consider the daily barrage of advertising many people get to be a form of brainwashing. In that context, women are very definitely being subjected to daily abuse. But you seem to be saying that because we're adults and can make our own decisions, that type of manipulation is perfectly OK, that's it's insulting to even suggest that it's an influence on women's career choices. I think many people ignore small, daily, accumulated brainwashings like this, in much the same way the frog doesn't jump out of the pot if the heat is increased slowly over time.

Do you have any studies (or anything else) which demonstrate a clear link between advertisements and career choice? This reminds me of the "video games will make you violent" argument that lasted for a decade or so before the assertion was conclusively put to rest. I don't think you're giving humans enough credit.

You need to stop looking at this as an all or nothing problem. It's not just culture that creates this gap, NOBODY has been saying that! It's much more likely that there are many factors to be considered.

I never said it was an all or nothing problem, nor did I ever imply it. I was careful to phrase my reply as a question -- as in "do/don't you agree with this(?)". If you go back and read my posts I was careful to say biology plays at least some role. I never said it was all biology, and I never said culture plays no role.

You seem to need women to be hard-wired against science biologically, with no influence from the culture they're born into.

I'll ask that you don't attempt to psychoanalyze what I 'need.' It puts me in the uncomfortable position of having to defend my own feelings, which you have now portrayed as possibly deranged.

Does it absolve men from trying to help if it's just a nature thing?

If the gap is the result of human beings making life decisions, what is there to help? Do you want to somehow socially engineer all careers so that the demographics are 50-50? Why? Wouldn't that just shift lots of men and women into fields they don't really want to be in? That's the opposite of helping.

In free societies where people are free to choose their own careers, gender gaps inevitably form. This is a demonstrable fact, and I don't find it to be a "bad" or "wrong" phenomenon. Just like I realize men will continue to die at ~20x the rate of women at work, commit suicide at ~5x the rate of women, and the prison population will probably always be ~90% male. Equal opportunity does not always result in equal outcome.

As an aside, this seems like a defense for why men should get better pay than women, because they take more risks and die at work more often.

That's pretty perpendicular to the point I was making (my aside was still driving the same point), but I would agree that people who take risks for their job should be compensated.

Off the top of my head, I'd say just replace "female crowd" with "women". If you were trying to discuss men in STEM, would you really call them "males"? And I know it's just an argument from incredulity, and fairly worthless because of that, but I can hardly believe you would ever refer to men in STEM as "the male crowd".

Well, I'd personally never refer to any group of people as "the X crowd." Not because it's disrespectful, but because that combination of words is not really in my vocabulary. I'd also personally not find it particularly offensive if thread's title was, for example, "why is the male crowd not attracted to nursing(?)".

I take it you didn't bother reading past the first sentence or paragraph? That was hardly the point intended when I shared that link. Consider exploring the next several sections if you're genuinely interested in better understanding my perspective.

You didn't link to those sections. You linked to the "biological explanations" section, for which there is only a short paragraph about spatial intelligence. What am I supposed to assume when you link to a specific section of a wiki page?

To further Phi's point, of course nature and nurture both always play various roles, but nearly everything in the literature on this specific issue points heavily toward the role of nurture / socially imposed obstacles / family and cultural expectations and feedback, and similar nonbiological explanations. That said, there's no need to continuously strawman and misrepresent others if for some reason you disagree and hold a different perspective.

I completely understand what you're saying. I'm definitely not trying to misrepresent anyone's position. If you can locate any instances where I have done so and not corrected myself, please point them out.

This entire forum reeks of it, that's my point, how thick are you people!?!

 

Honestly, I'd rather have the negative rep than consider myself part of your lot, disadvantaged by an uptight outlook on everything.

The problem is everybody else? Good luck convincing everybody else.

How is it a blanket declaration? I basically said I think the problem as presented here is more nurture than nature.

 

And you can stop crying, because your misleading vividness isn't really helping this discussion. You're resorting to some uncharacteristic fallacious logic, when you're normally very careful about that.

I suppose I could do without the colorful language, but I don't understand your objection. You think the gender gap in STEM is mostly cultural in origin. You assume (or at least implied) that cultural influence is driving women away from the careers they really​ want to be doing. I just find the lack of respect for womens' agency a bit irritating. These are adult women making adult decisions about the fields they want to go into. It almost sounds like you're saying they've been brainwashed by society into not majoring in engineering.

The notion that culture is creating the gap is hard to see. Shouldn't this mean that in gender-egalitarian societies the STEM demographics should float somewhere around 50-50? Because that would be demonstrably false. See, e.g., Norway, Sweden, and Denmark.

As an aside, it's also a bit funny that nobody ever mentions the workplace-death gender gap, which is about 20:1 male to female workplace deaths. Do you think this is culturally motivated? Do you think males are biologically predisposed to be willing to do more dangerous work? The latter is certainly demonstrable, with testosterone being positively correlated with risky behavior.

Seriously? You don't think referring to the "female crowd", as opposed to the men in STEM, isn't setting up sides?

Not really. No more than "male crowd" would be, at least. How would you rephrase the title to make it seem less divisive?

And really, when did you start resorting to strawmen so often? My stance is clearly "more nurture than nature", not "biology absolutely does not under any circumstances have any sort of..." Yeah. It's like a parody of strawmanning. Why?

I wasn't referring to your stance (which I thought was pretty plain from the wording and context -- but I guess not), I was referring to the general sentiment of the thread. The original source of disagreement was between myself and iNow, because he expressed incredulity at the notion that biology had much if anything to do with it. Obviously my wording was hyperbolic, so if that annoyed you I apologize.

I will retort by saying, I did not feel it was my responsibility to educate anyone on the 5 basic string shapes or the specifics of what a trion re is for the very same reason that I would not take the time to educate someone on what the value 1+1=2 actually means. Just because the words I used sounded "buzzy" due to lack of knowledge on the subject, does not at all make what I am saying a "buzz word salad", but I will respect your opinion.

 

I would rather someone refrain from responding at all rather than trashing my work because they have no clue as to what I'm talking about due to their narrow view of universal theory. What I was looking for was an intelligent thought provoking response by people of the same caliber of knowledge. Unfortunately, those seem to be far and few between.

This is why you get negative rep points. Because your posts reek of arrogance and condescension.

I've clarified it several times now for you, yet you appear to be incapable of accurately comprehending my position.

http://en.m.wikipedia.org/wiki/Women_in_STEM_fields#Biological_explanations

Your position is that males have on average better spatial intelligence? Okay. That seems corollary to my point. Your previous posts (save the one where you originally posted the wiki link) seemed to express incredulity at the notion of biological explanations.

Yet in the post immediately preceding this one you said you had. Which is it? Make up your mind.

I have been using the qualifier "in part" throughout. I used "could be" once, in reference to your thinking it is bizarre that biology "could be" a factor. That doesn't mean I'm saying it isn't a factor. It's a statement about your position, not mine.