Cap'n Refsmmat

Yes. This four-dimensional length reflects the spatial and temporal distance between any two events; in other words, it's a distance through time and space. It "actually" means [math]s^2 = \Delta x^2 - c^2 \Delta t^2[/math]. I'm not in a position to explain ontologically because an ontology is not empirically observable, and hence outside my purview. Whoa. Earlier (post #133) you wanted to choose a reference frame where an object is stationary; now you say that no such frame exists. You say "if an object is moving at constant velocity" -- relative to what? Relative to object A it may be moving at 20 m/s and relative to object B it may be moving at 10 m/s. Your virtual marker be retro-jetted to be stationary according to whom? As you said, "velocity requires a specific reference, i.e., relative to what?", so I'm going to choose a specific reference that is the object which is moving. There. Relative to itself, it's not moving. It's stationary. By your argument, that's "the preferred frame for objective accuracy of measurement". So it's not moving. So an interval for the elapsed time for its motion is null, because it has no motion. How does that work? Your scenario does not make sense. I thought we were talking about how relativity works with frames of reference. Would you prefer to talk about some other theory that doesn't involve a four-dimensional spacetime? A dimension. No. A day is 86,400 seconds and a year 365.25 days.

There are properties independent of measurement and observation from different frames of reference. They are called "invariants," and they are very useful in relativity. Spacetime intervals are one example, but there are many others. In short: there are properties of reality which do not change no matter who you are or where you are. There are other properties that do. Unfortunately, these properties do not match your expectations. Have you conducted an unbiased scientific investigation into the reasons for the existence of the dictum?

Could you point out which part of the quote equates thermal energy with heat? Here's another quote you might find relevant: "Heat may be defined as energy in transit from a high temperature object to a lower temperature object. An object does not possess "heat"; the appropriate term for the microscopic energy in an object is internal energy." http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/heat.html#c1 Incidentally, swansont is in the same position, being a professional physicist who contributes to SFN because he cares about helping other people understand science. I'm disappointed with the tone of this discussion. swansont, whether he's wrong or right, has calmly and civilly explained the physics as he explains it, and you've responded with angry, bolded, all-caps rants. Please try to follow SFN rule 1 from now on.

Perhaps this concept is more promising: http://dsc.discovery.com/news/2007/11/29/engine-car-stop.html ...although the article is a bit crap in places. (The user could aim the microwave beam at the lug nuts? Really? What do you expect that to achieve? "Oh dear, my lug nuts are four degrees warmer!")

There's a couple fairly hard problems to overcome: Making the sensor tamper-proof, and making it only usable by the police. If you build such a device, and one of the police's special car-disabling devices is stolen, is there a way to prevent it from being used to stop cars willy-nilly? Is resolving car chases worth this public safety hazard?

Any physical movement relative to what? After all, if an object is moving at a constant velocity, we can switch to its perspective. In its perspective, it's stationary, and other objects are moving past it. (You've already considered that velocity is relative.) This would imply that from some perspectives, an interval of time elapsed, and from other perspectives, time did not elapse at all. How does that work? Why is the burden of proof on me? The following proposition is fundamentally different from yours: Length is one dimensional, a straight line from one point to another. A plane is area, with two dimensions. Space (volume) is three dimensional. Spacetime is four dimensional, and time is a dimension unrelated to movement from point to point. This is the view of relativity, and it must be true for numerous experimental results to make sense. If you wish to suggest otherwise, you need to formulate an alternative that can account for those experimental results.

This is, in fact, quite true. You just err when you assume three-dimensional length is an intrinsic property, rather than four-dimensional length. In special relativity, reality comes in four-dimensions. Properties such as the spacetime interval, which is four-dimensional, are invariant between any reference frame, and hence "intrinsic" enough for you. Three-dimensional length or shape is not. Is there a name for the philosophy "reality is real, but we all see different parts of it"?

This would not be a problem if you didn't rashly reject the notion of "spacetime", because in four dimensions, you simply change coordinates. No shape change required. No morphing.

In any given reference frame, the Earth never changes shape. Two people in two different reference frames can concurrently view the Earth as being different shapes, but the Earth never changes shape in a single observer's frame. This works if you consider a four-dimensional spacetime. Length contraction in four-dimensional spacetime is not a "morphing" of shape or a result of any change in shape by the object whatsoever. It's a result of different portions of the object being visible to different reference frames; we see a three-dimensional "slice" of the 4D object.

A constant c does not invalidate any claims of Earth science, and Earth science's many tests and observations are not relevant. As I posted some days ago: One might extend that with the predictions of each in a reference frame moving very fast relative to Earth: Earth science: Dunno, never looked at Earth while moving fast. Newtonian mechanics: Nearly spherical Earth. Relativity: Oblate spheroid Earth.

jeskill: Greg won't be replying here any longer, as his persistent bad behavior has led to his Politics access being revoked.

Because constant c is one of the most-tested predictions of physics. http://math.ucr.edu/home/baez/physics/Relativity/SR/experiments.html#round-trip_tests

That has nothing to do with the statistics I posted, nor does it contradict them, so your objection is still unsubstantiated. You've been warned enough.

Either you do not understand what "be civil" means or you wish to have your access to the Politics forum revoked. No. Your inductive reasoning is only valid if you can sufficiently exclude the other possibility: that monotonically growing species exist, but you have not detected them for whatever reason. Prove it. Why should I take your word for it when I have the word of scholars and experts in the field? http://www.nizkor.org/features/fallacies/ad-hominem.html http://www.nizkor.org/features/fallacies/guilt-by-association.html Rule 1.c

No, you didn't. You said: That's hardly an argument. You've since provided a number of "in my opinion" and "I doubt that I would have much trouble at all finding figures that contradict yours" statements without any actual figures, evidence, or reasoning. Hm. Interestingly, decreasing child mortality can decrease fertility rates. One can see that improving the economy of third-world countries, sending medical aid, and providing educational services can have strong a impact on fertility and population growth. http://www.eubios.info/EJ124/ej124i.htm

As swansont said, energy is a property and not a thing. This is like asking why you can't create pure tall. You can't have pure tall; you can just have very tall things.

I don't think any scientist is in the position to predict the social and societal consequences of a given piece of research. Scientific revolutions -- and individual products -- generally come from many pieces of research building new knowledge over years, rather than a single scientist saying "I'm going to solve this problem and incidentally cause overpopulation in sub-Saharan Africa."

Because mass is a property of things, not a thing. That's like saying energy turns into blue, instead of saying it turns into something that is blue.

Hm. That's a bug in my code, not your fault; it looks like the system that puts recent blog posts on the front page didn't notice that your posts were deleted. I've removed them manually. Feel free to re-post. In the future, you shouldn't need to delete posts if there's something wrong with them; you can edit them or set their status back to "draft" to make them invisible again while you edit.

To the best of my knowledge. If there's another one, I'm not in it.

"Mass particles" are by definition matter, since matter is any particle with mass and volume (in a simple definition).

Because the angle decides how far the photons travel through the thin film before being reflected on the other side, and hence how the reflected waves line up. Some waves reflect off the surface, and some travel through and reflect off the other side of the film. (See this diagram.) When they combine after reflection, those that traveled farther may be out of synch and destructively interfere; the amount of interference is dependent upon the additional distance the waves traveled.

A rainbow on a thin film is a result of thin-film interference: http://en.wikipedia.org/wiki/Thin-film_interference

Individually, yes, matter or energy can be destroyed, but taken together, they are conserved. The theory of relativity suggests that matter is just a form of energy.

In my experience, people take offense at measures like this, and they invariably become stubborn and unwilling to learn. Consider how they perceive it: "I posted my opinion, people disagreed, and now I've been forced into some special forum for nitwits because I took an unpopular position." Furthermore, how do you maintain continuity when posts are shunted into separate forums with regularity? Discussions would be disjointed and difficult to follow.