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AoA, a worthwhile read

He was a MIT professor, prolific inventor, artist and by all acounts an incredibly nice person.

He's also responsible for one of my favorite quotes:

Work like hell
Tell everyone everything you know
Close a dread with a handshake
Have fun

Is glass liquid or solid? says:
There is no clear answer to the question "Is glass solid or liquid?"...
...glass is a supercooled liquid... is also a popualar belief...
more of this also here another page

I personal think of it as a supercooled liquid. Just think about how glass is blown into its shape.

Obviously the Spanish Inquisition got to them first. Incidentally, the link says the Catholic Church finally agreed the Earth wasn't at the centre of the solar system in 1983!

The Bogdanov Affair

Although this, like the Sokal hoax does have a lot of fun at the expense of literary critics, it is hardly a problem merely in postmodernist circles. Evidently in modern physics one can fairly easily do the same thing -- the
Bogdanov twins evidently published several physics papers that are complete nonsense in the respected journal Classical and Quantum Gravity

What actually happens is this: the "diver" passes through the event horizon and is torn apart by the singularity in a finite proper time. An outside observer sees the black hole evaporate in a (very long) finite time, and he sees the diver pass through the horizon at the instant the hole shrinks to zero: but this just has to do with what the light does. The diver himself is long gone.

See the "What About Hawking Radiation?" section of this FAQ.

You are quite correct; I don't think any educated person would disagree with your assertion that environmentalism is not a science.
From WordNet (r) 2.0 :

environmentalism
n 1: the philosophical doctrine that environment is more
important than heredity in determining intellectual
growth [ant: hereditarianism]
2: the activity of protecting the environemnt from pollution or
destruction

The inductive approaches to physics, biology, and chemistry are sciences. These form the basis of all scientific research concerning the environment of our planet.

To learn more about the scientific method you will want to read this article about Francis Bacon and his advocacy of an inductive method (which is now generally called "the scientific method"), and a more detailed article describing the scientific method in some detail.

I'd have given 2 cuckoos to tachyons, only 1 cuckoo to time travel

In special relativity, faster than light travel (FTL) implies time travel quite directly.

So to treat the two subjects as being significantly different means to be working in a theory other than relativity.

Special Relativity (SR) is nice and simple but fairly limited in scope, but agrees extremely well with experiments within that scope.

Its extension to cover gravity, General Relativity (GR) is extremely elegant, and also agrees well with experimental observations, but is not integrated with the rest of the infrastructure of fundamental physics (quantum physics, quantum electrodynamics, the Standard Model...)

So general relativity may eventually become obsolete, even though currently it's currently a great theory, and whatever replaces it may modify special relativity too. So this isn't some kind of absolute statement.

Still, in the absence of a theory that is trying to supplant relativity, FTL implies time travel. Presumably the author of the book knows this, despite listing FTL and time travel as two different subjects.

For more info see these two sections of the relativity FAQ: relativity: time travel and relativity: FTL , hosted by and partly written by John Baez, a quantum gravity researcher with impeccable physics background (I've done some online study under him; he's also a fantastic teacher).

I'd have given 2 cuckoos to tachyons, only 1 cuckoo to time travel

In special relativity, faster than light travel (FTL) implies time travel quite directly.

So to treat the two subjects as being significantly different means to be working in a theory other than relativity.

Special Relativity (SR) is nice and simple but fairly limited in scope, but agrees extremely well with experiments within that scope.

Its extension to cover gravity, General Relativity (GR) is extremely elegant, and also agrees well with experimental observations, but is not integrated with the rest of the infrastructure of fundamental physics (quantum physics, quantum electrodynamics, the Standard Model...)

So general relativity may eventually become obsolete, even though currently it's currently a great theory, and whatever replaces it may modify special relativity too. So this isn't some kind of absolute statement.

Still, in the absence of a theory that is trying to supplant relativity, FTL implies time travel. Presumably the author of the book knows this, despite listing FTL and time travel as two different subjects.

For more info see these two sections of the relativity FAQ: relativity: time travel and relativity: FTL , hosted by and partly written by John Baez, a quantum gravity researcher with impeccable physics background (I've done some online study under him; he's also a fantastic teacher).

Seems as true as ever in this case. This puts the Fundamentalist Christians, the Libertarians and the Techno-Liberal-Anti-Ashcrofters squarely on the same side.

Heh. I hadn't thought of it in that way. Once you look at it, though, it makes perfect sense. It works like Ockham's Razor for the non-scientist.

To paraphrase:

If most groups with diametrically opposing views agree, then their view is most likely correct.

I like it!

This is something I've been thinking of doing for a while - all you need is a minimal OS install on the laptop (enough to provide a graphical display and networking) and an app that'll do a continuous slideshow of the images in a given directory (either local or remote)

I've been using this screensaver on my Desktop PC (Windows, I'm ashamed to admit), which is a clone of the screensaver in OSX (does nice zooms and fades between your photos)

Then you just dismantle the laptop, fold it up so the keyboard can be hidden away (or removed entirely, if the machine can cope) and re-mount it in a nice frame

Lies, all lies!

So, my speculation about aerospace ties were correct.

http://pah.cert.ucr.edu/~bob/shameful.shtml

This example is just one small section from one page. The person who created it was a web-novice, but a computer expert. Even he couldn't get Front Page to produce decent HTML (I don't think anyone can).

This is an urban legend. Glass is not a molten superfluid, supercooled liquid, etc. It is an amorphous solid. Old windows do not flow. Soda is used to reduce the melting point of sand in making new glass; it works the same way as putting salt on ice does. Adding old glass reduces the melting point the same way puting frozen saltwater on ice would, but that doesn't buy you anything--you can just as well uses some of the glass you just made, and you won't have to haul it for miles.

-- MarkusQ

For problems with the hexadenions, see the bottom of Week 59 (Toby Bartels's post).

UCR makes us paranoid about cheating. When they catch someone cheating, the person gets an F in the course and the choice of going to a seminar, or getting suspended for a quarter. If the person chooses to fight it, I believe he/she will be suspended for a year if the person can't prove that there wasn't cheating.
To catch cheating, they use MOSS, and an anonymous cheating report form

If you cheat twice, you're likely to get suspended for a year or get expelled.

The policy on academic dishonesty

UCR makes us paranoid about cheating. When they catch someone cheating, the person gets an F in the course and the choice of going to a seminar, or getting suspended for a quarter. If the person chooses to fight it, I believe he/she will be suspended for a year if the person can't prove that there wasn't cheating.
To catch cheating, they use MOSS, and an anonymous cheating report form

If you cheat twice, you're likely to get suspended for a year or get expelled.

The policy on academic dishonesty

UCR makes us paranoid about cheating. When they catch someone cheating, the person gets an F in the course and the choice of going to a seminar, or getting suspended for a quarter. If the person chooses to fight it, I believe he/she will be suspended for a year if the person can't prove that there wasn't cheating.
To catch cheating, they use MOSS, and an anonymous cheating report form

If you cheat twice, you're likely to get suspended for a year or get expelled.

The policy on academic dishonesty

In fact, some physicists have even considered the possibility that space is a Poincare homology 3-sphere! Can light go all the way around in this case? I don't know. If so, we might see bright quasars in a pretty dodecahedral pattern.

Amusingly, Plato hinted at something resembling this in his "Timaeus":

6) Plato, Timaeus, translated by B. Jowett, in The Collected Dialogues, Princeton U. Press, Princeton, 1969 (see line 55c).

This dialog is one the first attempts at doing mathematical physics. In it, the Socrates character guesses that the four elements earth, air, water and fire are made of atoms shaped like four of the five Platonic solids: cubes, octahedra, icosahedra and tetrahedra, respectively. Why? Well, fire obviously feels hot because of those pointy little tetrahedra poking you! Water is liquid because of those round little icosahedra rolling around. Earth is solid because of those little cubes packing together so neatly. And air... well, ahem... we'll get back to you on that one.

But what about the dodecahedron? On this topic, Plato makes only the following cryptic remark: "There was yet a fifth combination which God used in the delineation of the universe with figures of animals."

Huh??? I think this is a feeble attempt to connect the 12 sides of the dodecahedron to the 12 signs of the zodiac. After all, lots of the signs of the zodiac are animals. The word "zodiac" comes from the Greek phrase "zodiakos kuklos", or "circle of carved figures" - where "zodiakos" or "carved figure" is really the diminutive of "zoion", meaning "animal". There may even be a connection between the dodecahedron and the "quintessence": the fifth element, of which the heavenly bodies were supposedly made. I know, this is all pretty weird, but there seems to be some tantalizingly murky connection between the dodecahedron and the heavens in Greek cosmology.... so it would be cool if space turned out to be a Poincare homology 3-sphere. But of course, there's no reason to believe it is.

As I recall from my physics masters with major option in astrophysics, Olbers' paradox is used to discredit an infinite universe. You can check that from this explanation. Fair enough, in an infinite universe, the dust won't matter. In a finite universe with a finite age, it most certainly will, because it will take time to heat up enough to emit light. We could easily at a stage where the dust has not heated up to its equilibrium temperature yet, and is still absorbing more energy than it is emitting.

You need to check your physics. (and I should check mine, but unfortunately my physics knowledge doesn't come into my current work very much, especially not my astrophysics).

Daniel

If I read you correctly, you'd want to assume that electromagnetism can be built on a single vector potential and then conclude (from the theory that you get this way) that magnetic monopoles don't exist. Sorry, but this is utter nonsense. If you had taken a basic course on electromagnetism, you'd know that the ability to describe electromagnetism with a single vector potential depends on the fact that the divergence of the magnetic field vanishes and it - just like I said in my previous post - only vanishes if magnetic monopoles don't exist.

In other words, assuming that one vector potential is enough is equivalent to assuming that magnetic monopoles don't exist. Your argument really says nothing else than "if you assume that magnetic monopoles don't exist, then magnetic monopoles don't exist".

Quantum field theory is very successful experimentally (as successful as epicycles would be with the use of an unlimited hierarchy), but it is notably unsuccessful philosophically; there is no unity of substance in the theory.

Oh dear. Please check your cracpot index before further explicating your personal philosophy.

Short informative read:
http://math.ucr.edu/home/baez/physics/Relativity/S peedOfLight/measure_c.html

SNK trumped the 16 bit competition by releasing their 24 bit NeoGeo powerhouse.

NEC releases it's 16 bit system to compete with the 16 bit Sega Genesis.

Sega's last stand, the Dreamcast is a 128 bit super system that will change the world.

No thanks people. I'll just stick to my PC which includes the powerful 80 bit 8087.

Not sure but was wondering wouldn't this be a kind of exception to Heizenberg since absolute zero is the state of no movement then it would seem you would lose the uncertainty in location because that wasn't changing.

Actually as much as you might think this... it's not! In fact, even situations where you surely would think the uncertainty principle doesn't apply, it turns out it does!

In an "empty space", you would think energy was zero. However, the uncertainty principle applies to all conjugate quantum variables (position/momentum, energy/time, etc)... So in any amount of space, if you measure the energy in it over a certain amount of time, you always have some uncertainty. Thus "empty space" must be seething with a roughly uniform amount of random energy.

The Casimir Effect is a manifestation of this which as been experimentally verified. Weird, eh?

As another poster mentioned, the Bose Einstein condensates form precisely due to this Heizenburg "expansion" due to cooling, and so Absolute Zero really isn't reachable. Sorry.

Cheers,
Justin

Here's a tip: If you drive me to read your material, you are NOT likely to garner a favorable/constructive review.

I'd be willing to read what you've done, but if you trick me into hitting your page, the best you can hope to get is my leaving without crapflooding your guest book. Someone looking for a book review finding your site would be a good thing, probably for all involved, but this is not a desirable reason to Google bomb. This guy wanted the phrase "ruby orange" to point to his page, based on a photo of the kid (named Ruby) having just had her foot dipped in orange paint. For something as simple as a baby photos page, it would probably be cheaper/easier to register a domain name, or even to have a couple hundred cards printed up with a URL. How about creating an emailing list and telling people where to sign up?

I've got a few pages on the web, and several of them are loaded with photos of my son, who will be a year old in three weeks. I haven't plastered his web site all over creation using a method that's just likely to draw tons of strangers in to view them. I tell people I see when I know they'd be interested, and I email or call people that I don't see. As many creeps are on the 'net, I sometimes consider putting passwords on the pages. If I had a daughter like this guy, I'd be nervous to even POST photos at all.

And what about the people who

• are in the market to buy some ruby blood oranges?
  
  
• or maybe ruby red grapefruit?
  
  
• would like a new, better recipe for a ruby orange cream torte?
  
  
• are trying to find Ruby and Orange throw pillows
  
  
• to match their lovely Ruby and Orange table covers?
  
  
• or even their quasi-antique ruby orange candy dish?
  
  
• can't remember where they bought that tasty fruit basket (was it Pepperige Farms? Knott's Berry Farm? Old McDonald's Farm?) last year?
  
  
• there will even be more people researching Kentucky women named Orange having daughters whom they name Ruby than people looking for this man's one child.
  
  

Thinking of "curves" in space-time is an interesting analogy for gravity, but still doesn't address the mechanism - sure, the planet may be on a "45 degree" incline in spacetime, but what forces it down... and not up?

That is the wrong question. Curvature is an intrinsic property of any spacetime; unless you are standing on something, there is no notion of down, up, or 45 degree incline. These notions arise only when using simplified "rubber-sheet" analogies to describe the effect of mass on the geometry nearby.

You would nearly have to posit the existence of some constant stream of gravitons coming at 'right angles' to three-dimensional space in order to actually push things 'down the well'.

This is meaningless. General relativity is a purely geometric theory, and says absolutely nothing about gravitons. It would be nice if people trying to poke holes in relativity (e.g. van Flandern) took the time to understand what it actually predicts.

Incidentally, do any of these alternative theories predict the proper precession of Mercury's orbit, or the timing adjustment for clocks on the GPS satellites? General relativity does. This page might be useful to people who haven't seen these sorts of debates before.

Better?

Yes of course it has to be made more accurate, and that's just what this professor at UCR's, Department of Electrical Engineering is working on. To quote what he says about it:

Global Positioning Systems: Accurate vehicle control requires reliable, accurate, high rate vehicle state information. We have developed and demonstrated a differential GPS/INS system to provide full six degree of freedom vehicle state information. Using GPS carrier phase and/or magnetometer measurements, we currently attain 2.5 cm. std. horizontal position accuracy. The INS provides the estimates at a higher rate (>150Hz) than the GPS itself is capable of providing. In addition, the INS maintains the vehicle state during brief periods of loss of GPS signal.

He also has some mpeg demo's available and also some reports (if you are really interested) on his home page (linked above).

Yes of course it has to be made more accurate, and that's just what this professor at UCR's, Department of Electrical Engineering is working on. To quote what he says about it:

Global Positioning Systems: Accurate vehicle control requires reliable, accurate, high rate vehicle state information. We have developed and demonstrated a differential GPS/INS system to provide full six degree of freedom vehicle state information. Using GPS carrier phase and/or magnetometer measurements, we currently attain 2.5 cm. std. horizontal position accuracy. The INS provides the estimates at a higher rate (>150Hz) than the GPS itself is capable of providing. In addition, the INS maintains the vehicle state during brief periods of loss of GPS signal.

He also has some mpeg demo's available and also some reports (if you are really interested) on his home page (linked above).

Yes of course it has to be made more accurate, and that's just what this professor at UCR's, Department of Electrical Engineering is working on. To quote what he says about it:

Global Positioning Systems: Accurate vehicle control requires reliable, accurate, high rate vehicle state information. We have developed and demonstrated a differential GPS/INS system to provide full six degree of freedom vehicle state information. Using GPS carrier phase and/or magnetometer measurements, we currently attain 2.5 cm. std. horizontal position accuracy. The INS provides the estimates at a higher rate (>150Hz) than the GPS itself is capable of providing. In addition, the INS maintains the vehicle state during brief periods of loss of GPS signal.

He also has some mpeg demo's available and also some reports (if you are really interested) on his home page (linked above).

Yes of course it has to be made more accurate, and that's just what this professor at UCR's, Department of Electrical Engineering is working on. To quote what he says about it:

Global Positioning Systems: Accurate vehicle control requires reliable, accurate, high rate vehicle state information. We have developed and demonstrated a differential GPS/INS system to provide full six degree of freedom vehicle state information. Using GPS carrier phase and/or magnetometer measurements, we currently attain 2.5 cm. std. horizontal position accuracy. The INS provides the estimates at a higher rate (>150Hz) than the GPS itself is capable of providing. In addition, the INS maintains the vehicle state during brief periods of loss of GPS signal.

He also has some mpeg demo's available and also some reports (if you are really interested) on his home page (linked above).

Contrary to popular belief, there isn't any law of physics that says that matter compressed past a certain density must form a black hole. And no, our universe isn't really analogous to a black hole. Try this FAQ.

Science used to "know" the world was flat. They used to "know" that the sun revolved around the earth, and that the human heart worked just like a furnace.

Just as with any other post on /. on groundbreaking physics there should be a reference to John Baez' index for rating potentially revolutionary contributions to physics. I wonder how much points this guy is going to score.

why evolutionists think they have a right to disregard creation theory just because they fail to understand it

Evolutionism is based on facts while creationism is based on faith. Ockham's razor please ? Whether people know creation theory or not is not even relevent here ; your methodology blows godly goats compared to science's, even if science has indeed some bias. Comparing the bias of evolutionism and creationism bias is like comparing that of Hubble and Sputnik.

Actually, as the URL you gave seems to imply, Alan Sokal is a physicist, but his article was published in Social Text. The other one you're probably thinking of was the Bogdanov brothers; unlike Alan Sokal, their paper was (apparently) not intentionally gibberish.

some places things do roll uphill

Main point: he goes into the frame of reference of the light sail, notes that light_energy_in == light_energy_out, therefore no energy is transferred to the sail, and therefore there must not be any force on the sail.

But Energy is the dot-product of force . distance (likewise, power is force . velocity). 'No energy is transferred' is a different statement than 'there is no force' in the frame of reference of the sail (distance moved = 0, velocity = 0)

Radiation pressure has been successfully used by spacecraft for attitutde control and station-keeping.

Crookes radiometer does not turn due to radiation pressure.

He also has troubles with the concept of thermal equilibrium and inelastic collisions.

Is this really a thermodynamics issue?

What about this:
Casimir effect

Actualy 'true' radiometers have been built, but you have to use a pure vaccum, and cover the materal in a glass coating to prevent offgassing. It does work. see here

Actualy, in a perfict vaccume they spin the other (correct) way, assuming that the non-black side is a mirror.

I didn't see any reference to this article which nicely explains how Crooke's Radiometer works, with references. Note in particular the reference to an experiment showing that when the vacuum is perfect and friction is minimized, the vanes move away from the reflective side.

light-mill or radiometer do not rotate due to "radiation pressure" as I was once taught and is even the explanation provided in the Encyclopaedia Britanica today. Check out link above for an interesting description.

It's just a matter of different definitions. What was once called "rest mass" is now called "mass" -- it is invariant. (Actually, the concept of invariant mass is slightly more general than rest mass; it encompasses photons, which have zero (invariant) mass; their rest mass on the other hand is undefined, because they are never at rest.) The "mass" that changes with velocity is now called "relativistic mass-energy".

See this FAQ.

If there is dissipation there is loss of mass. Otherwise what is disipating ?

If all matter was compresed into a small area then it stands to reason there was an event horizon.

We don't have experimental proof yet, but we have overwhelming reason to believe antimatter fall down just like matter. You can work it out based on hysical constants and conservation of energy in a matter/antimatter annihilation. It is explained in this physics FAQ.

If antimatter is repelled by gravity then you either have a violation of conservation of energy, or physics constants are not constant.

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Memory Timing Explained.

GamersEd.com

Let us not forget snap, crackle, and pop.