Clearing Up Commonly Misunderstood Subjects/Terms in Science

[Gordon Freynman]

Inspired by a similar topic on another forum, common misconceptions I regularly see on this forum, and some posts in that recent debacle of a thread in the EMM, this is an attempt to clear up some of the commonly misunderstood or difficult to understand subjects, terms, and concepts in science and hopefully give readers a better understanding of the only subject actually worth studying the best method of understanding (and taking advantage of) nature. If you know of something that you feel needs to be explained and think you can explain it effectively, make a thread about it and I will index it here if it's good enough. If you have something that you want explained or think someone should explain, then post the suggestion in this thread and I'll add it to a list of requests.

Now, for anyone who wants to post an explanation here's a few guidelines to make sure explanations have a good level of clarity in them:

• Make it clear as to what subject you're posting about, a simple title would be fine
• Explain how/why the subject you're posting about is commonly misinterpreted, or why there is difficulty in understanding it
• Try to keep it as non technical as possible (i.e. layman's language). If you have to use something technical make sure it is well explained as well. It also helps to give your post decent formatting i.e. breaking up walls of text with smaller paragraphs, using proper spelling (get a spellchecker!), bolding or underlining important points, adding a summary to the end, etc.
• Give examples when possible. Examples are extremely important when learning about science as they help make difficult or confusing concepts more "down to earth" so to speak.

Index:

• An explanation of Relativity by Tankbuster
• The Big Bang: a brief guide by Gary88
• Wave/Particle Duality by chris_uk_83
• What does a "Theory" mean in Science? by Comrade Wiggum
• Conservation of Energy and the Big Bang by Vagn
• Common Misconceptions about the Big Bang by Comrade Wiggum
• Superfluids by chris_uk_83
• A Guide to Cell Structure by Acco
• Tyrannosaurus Rex: A Paleobiological Analysis by Nikos
• Allosaurus fragilis: A Paleobiological Analysis by Nikos
• Giganotosaurus carolinii: A Paleobiological Analysis by Nikos
• Spinosaurus aegyptiacus: A Paleobiological Analysis by Nikos
• Utahraptor ostrommaysi: A Paleobiological Analysis by Nikos
• The Heisenberg Uncertainty Principle by Comrade Wiggum

Don't let these sway you from making your own posts on the same subjects however (I know it wont stop me ). If you think you have something useful to add, go for it!

Requests:

• None as of yet

Other great science articles:

• LV's Biology thread by Belisarius
• "Bura-hara" by Acco
• The Global Warming by Freddie
• Western Diamondback Rattler by Nicholas Rush
• Mini science article: iron and iron processing by Da Goofy

[Gordon Freynman]

Allllllllllllllllllllllllllllllllllllllllllrighty then, the first thing I want to get started off with is...

What does a "Theory" mean in Science?

What I hope to do here is explain exactly what a theory means to science and how it relates with facts, evidence, and hypothesises (in science as well).

I often see the word "theory" implied as being a guess, i.e. "it's only a theory" "all they have is a bunch of theories," but this is a complete misapplication of the term, and most of blame for this would have to go to the popular media which frequently extrapolates it to situations where it shouldn't be used. What a theory is in scientific terms is a collection of concepts that are used to explain observed phenomena in nature. In order for a theory to be valid it must be testable, falsifiable, and make predictions about potential future observations. In physics the definition of a theory is slightly different, in that the explanation of observed phenomena is usually in the form of a mathematical framework. However it still has to have all the basic requirements of theory to actually be called a theory.

The difference between a fact and a theory (in science) is that a fact is something that is known to be true to by objective and verifiable observation, and a theory is the explanation used for facts, (so is a hypothesis but more on that a little later). For example, it is an observable fact that objects with mass have a tendency to attract one another, and the amount of attraction between objects increases as the mass increases and decreases as distance between the objects increases. The most accurate theory to date used to describe this fact is of course Einstein's Theory of General Relativity.

The difference between a hypothesis and a theory, is that a hypothesis is simply a theory which has yet to be tested. A hypothesis is developed to explain an observational phenomena, and through various sorts of experiments the hypothesis is either shown to be valid or not. If it is shown to be valid, then it is one step closer to becoming a theory (usually a hypothesis will need further development and testing to become a fully fledged theory).

I think that does it for a short and concise explanation of a scientific theory. Questions and suggestions for improvement are always welcome!

[Vagn]

Conservation of Energy and the Big Bang:-

First of all we must understand that the big bang is not an 'explosion' as such, the name was actually given by a critic of the theory, the big band is actually a theory that describes the expansion of the singularity for t > 0, i.e after the expansion first began 13.75 billion years ago. Before this general relativity falls apart, so we can not use it to determine what was occurring.

From the First Law of Thermodynamics (1st law of ThD), we know that in a closed system, we know that energy can not be made or destroyed, which leads to the question, how can something come from nothing?

Strictly speaking the answer is we don't know, as it is the default scientific position, however there are several hypotheses as to how it occurred:

It has been suggested that there are forms of 'negative' or 'anti-energy' which was created in equal amounts after the big bang, this would mean the total energy of the Universe is zero. One possibility is that gravitational potential energy, is the corresponding 'negative energy' and therefore whenever any energy is produced a gravitational field is also produced therefore hypothetically energy and thereby mass could be made without violating the 1st law of ThD.

There is also another situation in Quantum Mechanics where energy can be 'made'. In Quantum Electrodynamics, vacuums have energy coincidentally called vacuum energy and are filled with 'virtual particles' which are produced and annihilated constantly. These virtual particles consist of 'borrowed energy' from the vacuum itself, however they annihilate so quickly that the energy is regained by the vacuum rapidly.

We also do not know whether the universe is in fact a closed system, as recently a group of galaxies has been detected travelling faster in one direction than they should be, this was called the dark flow. We do not yet know what is causing the dark flow, and it may possibly be an experimental error, due to improber calibration of the instruments, however we are unsure.



I think that concludes this post for now.

Edit:- Perhaps there should be a scientific glossary in the first post?
Edit2:- Dark Flow added

[Gordon Freynman]

Common Misconceptions about the Big Bang

The Big Bang Theory is probably the most misinterpreted scientific theory in the general public. Here I will detail a couple of the most common misconceptions about the BBT and add more later as I think of or encounter them.

1) "The Big Bang was the creation event of the universe"

This is plainly false, although I can easily see someone making this interpretation off a poorly written article. The BBT can only be traced back to a time referred to as "time zero" or TZ for short, where our current best supported physical theories no longer work. Whether or not the universe was created at TZ or it existed before then is completely unknown at this point, but either way the BBT does not give an explanation as to how the universe came to be the way it was at TZ. Supplemented with Inflation theory, the BBT only explains what happened to the universe from TZ onwards.

2) "The Big Bang was an explosion"

Using the term "explosion" to describe the Big Bang isn't really appropriate. Doing so implies that A) the universe expanded from central point B) matter exploded into a preexisting space-time and C) the expansion of the universe was uneven.

All of the above are wrong. The Big Bang (including Inflation) was a metric expansion of space, which means space expanded equally in all directions everywhere. That is the key point to realize when saying that the Big Bang wasn't an explosion.

[Gordon Freynman]

Edit:- Perhaps there should be a scientific glossary in the first post?

That's a pretty good idea. I'll get to work on that as soon as...well whenever I get around to it I guess.

[Sphere]

As an engineer the use of the following terms gets under my skin for purely narcissistic/egotistic reasons. As such this is purely a rant, and if anyone actually learns something it will be by pure accident, and I apologize in advance.

Stress/Pressure
These are both words for the same idea; force over area. E.g. if you put a 1 newton weight on a wooden block 1meter square, the stress on the block is 1Pa. Stress generally pertains to solids while pressure is usually attributed to fluids, however there is no real distinction between them as they have the same units and can be used interchangeably. What gets to me is when people use units of force to describe stress/pressure. There cannot be 100lb of stress in anything, its a nonsensical thing to say. One can integrate stress over an area to get a force, but not before then.

Strain
Strain is not a force or a stress, but rather a measurement of distortion. Its often used in the vernacular as a substitute for stress, but its technical meaning is strictly a measurement of distortion as a percentage of original size. E.g. if a 10cm metal bar is stretched to 11cm its strain is 10% or 0.10. Stress and strain are related to each other mathematically through things like Youngs modulus, shear modulus and viscosity, but they are not the same thing in any way.

Force
Force is fairly straight forward and most people understand it adequately. However, it is irksome when force is used in conjunction with units of stress/pressure. You cannot have 100 psi of force just as you cannot have 1 square meter of volume. to get a force from a stress/pressure you have to multiply/integrate by the area over which that stress/pressure is acting.

[DisgruntledGoat]

What gets to me is when people use units of force to describe stress/pressure. There cannot be 100lb of stress in anything, its a nonsensical thing to say. One can integrate stress over an area to get a force, but not before then.

Generally when people say 20,000 pounds for pressure or stress they are using a short hand to psi (pounds per square inch). In fact, its the most common term used in industry. Say to anyone in industry "the steam is at 150 pounds" and they will instantly know that you are referring to 150 psi. This of course is only used in conversation and never appears in writing. Although I have a hard time imagining it being used in papers etc.

[Elfdude]

The big bang & Inflation.

Many people like to pretend that the inflation theory of the big bang is hypothetical unfortunately for them while the CMB (Cosmic Microwave Background Radiation) or CMBR provides spectacular evidence for the big bang the most important part is that it provides evidence for inflation theory.

Basically, the standard cosmological model of the universe runs into an issue when t, or time, equals 1 second.

The issue here is the that the big bang is described as an explosion. An explosion however is very chaotic and results in rather uneven pockets of energy and heat. Rather than confirming that there's these imbalances the CMB shows that the universe is largely homogeneous in temperature. This means that the universe must've expanded much more evenly. Between t>=0 and t<=1s the universe exploded. This explosion was hot and uneven. However inflation theory states that at around 1 second after the big bang the universe seemed to have 'stopped'. Instead of continuing to explode the universe suddenly stopped, then suddenly expanded to many magnitudes in size. This expansion or inflation occurred evenly in all directions.

The primary support of inflation theory is the CMB. Because the universe is homogeneous in it's distribution inflation must've occurred. Inflation also solves another problem with the big bang theory or the magnetic monopole problem. Essentially with super energetic hot energy in the big bang universe magnetic monopoles should've formed at dizzying rates and should infest the universe today. However we have failed to detect this high density of magnetic monopoles. Inflation theory provides a convenient fix to the problem that if the universe inflated in the early history the hot energies which would produce monopoles would be pushed far apart before they could form

Perhaps the most compelling evidence of inflation theory though is the so-called dark flow. Essentially all of the universe seems to be heading towards one point despite expanding so fast. Where is this place the universe is heading? Well, that's the interesting thing. It seems to be heading outside of our universe into another one.

Dark flow is still theoretical and is going through the review process but it's quite compelling and if it's true it could prove to be the greatest discovery of cosmological science ever. Proof of the multiverse. Proof of inflation theory. Proof of alternate universes.

[Marie Louise von Preussen]

Actually, if we ever considered how many gaps are still in astronomical theory, and most importantly how most of our astronomic insights are taken, no it's not granted.

In fact, astronomic hypotheses seem to be the most fragile part of Science, ever. It takes less than a year for us to be drowned in a gigantic wave of hypothetical babble, and it takes the same time before the latest Scientific American article clears the ground for more.

This is reinforced by the sheer vagueness of your own descriptions: "proof"? "Absolute" Space, then, is a self-contained dimensional measure within an even more "Absolute" Space, moving into another shell of "Absolute" Space due to an undetermined quantity "pushing" it.

That seems more, like a grotesque parody that tries to set things into motion just for the sake of it.

[Gordon Freynman]

Actually, if we ever considered how many gaps are still in astronomical theory, and most importantly how most of our astronomic insights are taken, no it's not granted.

In fact, astronomic hypotheses seem to be the most fragile part of Science, ever. It takes less than a year for us to be drowned in a gigantic wave of hypothetical babble, and it takes the same time before the latest Scientific American article clears the ground for more.

This is reinforced by the sheer vagueness of your own descriptions: "proof"? "Absolute" Space, then, is a self-contained dimensional measure within an even more "Absolute" Space, moving into another shell of "Absolute" Space due to an undetermined quantity "pushing" it.

That seems more, like a grotesque parody that tries to set things into motion just for the sake of it.

Not even sure what you are going on about, but it really doesn't belong in this thread what ever it is.

[Marie Louise von Preussen]

Not even sure what you are going on about, but it really doesn't belong in this thread what ever it is.

Care to define what's so wrong for you?

[Tankbuster]

Great idea, Wiggum!
I will definitely be reviewing and expanding my guide to relativity one of these days (with pictures ), but I'm so damn busy right now that I can barely manage anything more than two-sentence posts without feeling guilty.

Care to define what's so wrong for you?

Probably your pedantic objections to the linguistic place-holders we use in science while we wait for better data, and your suggestion that we should rely instead on... oh, that's right, you don't have anything else because science is - despite its flaws - the only effective and consistently reliable process for determining the nature of reality.

That and the thinly veiled anti-intellectual attitude.
Just a guess, of course.

[Gordon Freynman]

Probably your pedantic objections to the linguistic place-holders we use in science while we wait for better data, and your suggestion that we should rely instead on... oh, that's right, you don't have anything else because science is - despite its flaws - the only effective and consistently reliable process for determining the nature of reality.

That and the thinly veiled anti-intellectual attitude.
Just a guess, of course.

A surprisingly accurate guess.

I'm going to request that all posts not directly related to the original intent of this thread be ignored. This isn't the place to make pseudo-intellectual quips on how science is conducted.

[Marie Louise von Preussen]

It is interesting, because I analized this without regard to whether it is "true" or not. That is a job, I think, for extensive studying which has not been convened here. It is just a way of expressing how many fields of theory, particularly in physics, do have an uncanny resemblance with all too familiar shapes and concepts.

I wonder how you should think that language is an imperfect way of expressing a framework, when, lo and behold, all our formulations are done in language .

The rest of the reactions can be basically summed upon this: 'I love my podex, and I shall not get down from it!' Lol

[Elfdude]

Perhaps we can push for a subforum so that each of these concepts can have their own thread devoted to it with a appendix for threads that are good, contested or bad. Anathaneum would be more for news and popular science, a erroneo forum if you will would be more for explaining basic scientific concepts.

[Gordon Freynman]

Perhaps we can push for a subforum so that each of these concepts can have their own thread devoted to it with a appendix for threads that are good, contested or bad. Anathaneum would be more for news and popular science, a erroneo forum if you will would be more for explaining basic scientific concepts.

I initially thought it would be a little too much to push for a subforum at first, but after thinking it over I decided that this is probably the best thing to do. I PM'd Simetrical with the idea, so we'll have to see what he has to say about it.

[Gordon Freynman]

So, Simetrical told me we would need about twenty or so threads (separate topics) for a subforum to be considered, so we have a lot of work to do.

So I'm thinking we need to split the posts in this thread and make them each into their own thread, and then this thread will remain an index to all the explanations as well as a place where suggestions for new topics be made (also indexed).

[Gaidin]

The first problem with this thread is the vast majority of the people that refuse to listen to this kind of stuff don't come to the Athenaeum anyway. Should've put this as a stickied thread in Ethos.

[Gordon Freynman]

I've made my posts into separate threads, and I suggest elfdude, Sphere, and Vagn do the same because pending the approval of Simetrical this thread will be stickied an all current replies deleted and this thread will be for posting requests and suggestions only.

The first problem with this thread is the vast majority of the people that refuse to listen to this kind of stuff don't come to the Athenaeum anyway. Should've put this as a stickied thread in Ethos.

You can always just link the appropriate thread to the user using the index in the OP which saves time in having to constantly re-explain things to different people (and in some cases the same people ). That was part of the purpose I originally intended this to be anyway.