These thoughts are mine, but not all of them are original. When the thoughts are not original, I'll try to link to their sources.
Understanding Space, Time, and Gravity (14 April 2010)
Subtitle: Aether and gravito-electromagnetism (GEM)
The following comments should be most useful to you if you already have familiarity with special and general relativity.
How can we deepen our understanding of space, time, and gravity? Let's start with a quote from Einstein himself:
"The principle of relativity is a principle that narrows the possibilities; it is not a model, just as the second law of thermodynamics is not a model." --Albert Einstein**(This statement was made by Einstein in 1911 at a scientific meeting in Zurich. In 1911 Einstein was still using "principle of relativity" to mean theory of relativity.)
Why Special Relativity Should Not Be a Template for a Fundamental Reformulation of Quantum Mechanics
Now, if you want the kind of intuition that can only be provided by a model, you can go with a Lorentzian ether theory*, which can be made to be experimentally indistinguishable from Einstein's relativity (special and general). At least, I'm sure it can be made indistinguishable, I've never seen a definitive proof that it can't be made indistinguishable, and I've been told by a respectable mathematical physicist (John Baez) "I suspect it's probably easy to make up 'Lorentzian ether theories' that are experimentally indistinguishable from special relativity." Then it could be said there are only metaphysical/philosophical/aesthetic or pedagogical differences between these two perspectives. There are probably domains in which each perspective is preferable to the other, but I feel that the ether perspective makes more physical sense. Just because it's impossible to find the ether rest-frame doesn't mean you should throw it away! Occam's razor cuts differently given different values -- for pedagogy, I value intuition and speed of comprehension over "truth". Physics is a "tool", it's not the "truth". Whether an "ether" truly exists or not is of no consequence to me; what matters is the power of the ether tool to help me describe nature. (You might also ask is space-time a physical object that is actually curved, as so many people seem to imply or assume... and how objectively "true" is that? or is that just a mathematical analogy? and what is the physical interpretation of the metric? If you use curved space-time as your model or to guide your intuition, I'd say that's even less metaphysically justified than an ether model.)
*(The Lorentian ether theory I have in mind, at its most fundamental level, views the universe as excitations in quantum fields or a lattice of quantum oscillators, where there is a frame of reference at rest with respect to the lattice. However, the properties of the oscillators and their interactions make it impossible to find this rest frame. So an "ether" is a quantum field viewed as a physical entity and the luminiferous ether is the photon field.)
For a pretty good explanation of Lorentzian ether theory/ies, wikipedia-it: Lorentz Ether Theory
To see support for the ether-perspective given by John Bell (of Bell's Theorem), you can find it in a google-books preview. (That's where I read it, in Chapter 9 below.) Here are the sources:
John S. Bell, "How to Teach Special Relativity", Progress in Scientific Culture 1 (1976)
John S. Bell on The Foundations of Quantum Mechanics
Chapter 9. How to Teach Special Relativity
John S. Bell. Speakable and Unspeakable in Quantum Mechanics. Cambridge University Press, Cambridge, 1987
(You can also find relativity-perspective explanations of the spaceship paradox, but they all seem too complicated and far removed from the simple ether-physics.)
Now, for gravito-electromagnetism (GEM). Just as a 1/r^2 Coulomb force generates magnetism when the finite speed of the mediating photon is taken into account, a 1/r^2 Newtonian gravitational force generates "gravito-magnetism" when the finite speed of the mediating "graviton" is taken into account. So magnetism* is fundamentally an electric-force effect (this is even more obvious in the ether perspective), and gravity must have some analogous "magnetic" effects! Einstein showed that gravity should be non-linear, so we know that the graviton should self-interact. (General relativity also implies that the graviton should be spin 2.) Taking that self-interaction (and spin-2) into account should bring us all the way to the equivalent of general relativity. Presumably, in most of the universe (barring black holes, supernovae, et cetera), all you really need to know about gravitation is GEM to have an accurate description. (I could be wrong, though... we should see if GEM explains the previously "missing" precession of the perihelion of Mercury.) So even without an ether, one can speak of a classical spin-2 graviton field (in flat space-time) that generates gravitation. This gives a (more) physical model than talking merely about metrics and so forth.
You should read the Feynman Lectures on Gravitation (or just the foreword/preface and introduction) to see this particle perspective discussed at length. (Brian Hatfield, who wrote the introduction, is the same person who wrote Quantum Field Theory of Point Particles and Strings, the book that helped provide a key insight that went into Chris's and my research in QFT. For that, see the paper WTF is QFT? [pdf] in my Writings)
I wrote a very detailed (but unfortunately not-pedagogical) paper that showed how you can work backwards from the full Einstein gravitational field equations to get the gravitational analogue of electro-magnetism. See page 11 of the GEM paper and compare equations 8&9 with equations 10&11): Gravito-Electromagnetism [pdf] in my Writings
I think since the ether perspective makes more sense, it will be more useful in developing a quantum theory of gravity (and an intuitive perspective of any quantum field theory). However, it seems that the obstacle to this view is the EPR paradox and Bell's Theorem, since they seem to rule out "local" theories and ether uses local interactions only.
P.S. When I'm feeling artful, I use "aether", and when I'm feeling practical and concise, I use "ether".
Order of Nature, with respect to time-derivatives
In physics, usually we deal with measurable quantities that we can describe using functions of some other measurable variable (or some "parameter", such as time). We are often concerned with derivatives of these functions, usually first or second order derivatives, but rarely third or higher orders. There are some engineering applications that consider higher order derivatives, but fundamental physics seems to be devoid of anything beyond a second order derivative.
There may be higher order effects that we have not detected or modeled yet that will only appear given a large value of higher order derivative of, say, position with respect to time. A significant value of a higher order derivative may imply tremdous strain or pressure on macroscopic physical objects, which cannot handle such strain; thus a macroscopic physical object would more likely be broken or deformed than actually move with higher order acceleration. Smaller, more fundamental objects may provide a means to detect these higher order effects, but they might only become observable in very extreme situations, such as at very high temperature and pressure. But then, in such a situation, it is impossible to keep track of a large collection of super-heated particles, so the effects may show themselves in the statistics of the particles. However, such a situation may end up causing much particle creation and annihilation at the same time, making it very hard to distinguish the cause of each observed effect. (On the other hand, it may also be possible to construct controlled experiments with few particles that expose these effects.)
Most Important Issue and Ron Paul (October 20, 2007)
As I see it, the most important issue for the U.S., besides global warming, is the movement of our federal government towards tyranny (less-checked and secretive executive power, loss of liberty and privacy, adoption of preemptive military action, etc.), along with the long-time presence of secret-government activities and military operations.
The solution is to get rid of (or dramatically reduce) the offending parts of the government and secret-government, restore constitutional rule of law, limit the government to strictly constitutionally-based responsibilities, and increase government transparency.
Ron Paul is the only (major) candidate for the U.S. presidency who takes this stance, so I am supporting him. (I support no other Republican candidate and I am not withdrawing support for the Democratic candidates.)
Voting Methods (2006)
We should use various voting methods in our every day lives (e.g., when deciding among friends at which restaurant to eat). People need to become comfortable with different voting systems so they will accept a new voting system on a large (national) scale. (See May the Best Man Lose.)
Reasonable Politics (2006)
I would like to influence politics to be more scientific somehow. More fundamentally, I would like politics to be more philosophical as well. Expressed political stances should be accompanied by stated philosophical assumptions, and it should be clarified when differences of opinion stem from differences of basic assumptions or different lines of reasoning applied to the same assumptions, and so on. This should be common practice and people who refuse to do so should be seen as suspect and likely to muddy the waters. (As such, I should probably also state my own philosophical assumptions that support my opinions on this issue.) As for being more scientific, it should be more difficult to get away with misrepresentation, and claims should have to be verified by several independent sources before being recognized as valid. Some steps are being made in this direction, for instance, with FactCheck.org. Somehow, it should become commonplace for people to get news and analysis from several different sources.
These aims seem nearly impossible to achieve when you consider: the amount of time and effort it takes for an individual to become educated and well-informed (by several sources), the superficiality of current political debate and dialogue, how so much of politics is based upon misrepresentation of facts, the amount of influence one charismatic or devious person may have on a large segment of society, or how blind religious convictions can obstruct reasoned debate and compromise, et cetera.
"Discipline makes things easier / organize your life" -Dead Prez
"Abstraction makes things easier / organize your mind" - my corollary
A quote due to Dyson which simultaneously captures the excitement and drudgery of scientific research is "Anger is creative; depression is useless." (from ScienceWorld)
I've found that my room in my apartment is an excellent optics laboratory. Here's what I've noticed:
- Shadow distortion: Let's say you have a single bright source of light, such as the sun, casting light upon a smooth wall that is perpendicular to the incoming light rays. Let's say you have two objects placed at different distances from the wall and that they cast separate shadows onto the wall. When objects are moved such that the separate shadows approach, meet, and become one shadow, the shadow of the object that is closer to the wall distorts and stretches (or "leaks") towards and into the shadow of the object that is further away from the wall.
- Nimbi: Shadows of certain objects, such as my hands, are surrounded by a small region of light (a "numbus," if you will) that is brighter than the regions receiving direct, unobstructed light. I think this is simply due to the reflection of light off of the surface of the objects in question.
- Projection: If I hold my forearms up, side by side, so that there is a small slit between them through which light can pass, and if I allow bright sunlight that has passed through the gridded window screen to pass through this slit and onto the wall, then I can see the pattern of the screen projected on the wall. Actually, only the horizontal portion of the pattern is clearly visible (the dimension perpendicular to the slit), so the projected pattern looks like the vertical light and dark strips that you would see in the single-slit experiment. (At first I thought I was creating a single-slit diffration pattern with my arms, but this can't be, since the light from the sun is incoherent and made up of many frequencies. However, as the light is coming from the setting sun, the light may be more polarized than usual or have other properties of which I am unaware.) Furthermore, the image was magnified and reversed. This situation reminds me of the pinhole camera.
I'll post pictures of these phenomena as soon as someone volunteers to help me take the pictures. I think they may all be related.