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"Science is not a democracy. Facts, definitions and terms are not up for a vote."

The authority of a scientific view is derived from the strength of the scientific consensus that supports the view, every individual scientist has a duty to rally support for a different view if they belive the current consensus is flawed. That level of democracy in any human endevour is rare and is why the scientific community is sometimes called the republic of science.

"It is NOT how science works!"

Definitions for the scientific method, pick one or give me yours.

Maybe yes, and maybe no, depending on your point of view

Healthy skepicism is good, blind acceptance of and obedience to, rules, not.

Original NASA article
http://www.nasa.gov/vision/universe/starsgalaxies/ dark_matter_proven.html
John Baez (physicist who have a lot of fun staff on his homepage) more coherent explanation
http://math.ucr.edu/home/baez/week238.html

Good work! I've put up some more links to Markevitch's work here, and a simplified explanation of this colliding galaxy business:

This Week's Finds, Week238

I'm not an expert on this, so some of the details could be wrong. I'll fix them if corrected (please send email).

...The formula can also be applied to velocities in opposite directions by simply changing signs of velocity values or by rearranging the formula and solving for v. In other words, If B is moving with velocity u relative to C and A is moving with velocity w relative to C then the velocity of A relative to B is given by,

v = (w - u)/(1 - wu/(c^2))

Wouldn't this result in a real-universe equivalent of Zeno's paradox - i.e., wouldn't the collapsing mass always be moving closer to becoming a black hole but never arriving at that point due to the increasing time dilation?
It's a matter of perspective. An outside observer will never see a black hole fully form (although there will be a finite time at which the last photon from the collapsing star will be observed). However, an infalling observer will pass through the event horizon and hit the singularity within in finite proper time (measured by their own clock). See this FAQ.

Much of our current understanding of the cosmos is based directly on the correctness of the Theory of Relativity, but this finding (if confirmed) would appear to falsify at least some of relativity's conclusions.
No, MECOs supposedly are constructed within the framework of relativity. See this paper.

(I will chime in to agree with the skepticism of other posters; MECOs seem like a very contrived way to avoid the implications of black holes. Furthermore, general theorems in GR indicate that black holes form under very generic conditions, while no corresponding arguments exist showing how a MECO could plausibly form.

(This assumes that the MECO model isn't just plain wrong, which is possible, especially considering the publication record on this theory or lack thereof; I haven't studied the work closely enough to see if there are errors.)

Does this tenative finding square with string theory?
The cynic in me would say that any finding consistent with quantum mechanics and relativity squares with string theory...

Yes, I also think it's quite fun to program in assembly (if only debugging it was fun and easy too...). And as Randall Hyde says, the impact on project time of choosing assembly as a language isn't as big as people think; most of the time is usually spent in designing anyway. As you say, the biggest problem is portability today... That's probably the biggest reason why programs made completely in assembly are more and more rare nowadays.

Perhaps you'd find another work of Dr. Baez's useful: The Crackpot Index.

I'm not sure anything I say here will help, but it's worth a try. Being in academia, I've never seen any evidence that anyone is trying to suppress free energy research. Mostly, it's ignored, because it doesn't seem useful or reasonable. Academics, like other people, don't like to waste their time. People claiming "free energy" that I've seen simply don't seem to be able to speak or understand the language of physics and often demonstrate they do not understand existing physical theories, so that leads to even less interest. Academics do argue against ideas they believe to be incorrect, but in this sense they are no more suppressing free energy research than they are suppressing the research of collegues, because people often say they don't think another researcher's idea will work. The only difference is that there is extremely wide agreement that free energy research is nonsense. Academics generally have no interest in suppressing any ideas, and they generally do nothing to suppress these ideas other than expressing their opinion that the ideas are incorrect and giving reasons why that is so. Moreover, many wild ideas are floated in academia, often including ones that go against beliefs widely held in the scientific community (e.g. alternatives to quantum theory or general relativity), so it's not like it's an environment where everyone must speak in unison. The idea that free energy research is being surpressed is generally just a cover for not being able to defend those ideas or offer any convincing proof that they are correct.

Here is a this very nice discussion of the zero-point energy by mathematical physicist John Baez. You're right, the idea is hardly new, but some of the experimental evidence about the cosmological constant is relatively new.

I think it's fair to say that almost no physicists believe you can extract useful work from the vacuum energy. Most of the people claiming you can are con men trying to swindle people into buying "free energy devices" that supposedly tap the zero-point energy (it's the modern day incarnation of perpetual motion machines). While you may be able to setup a situation where the vacuum does work (i.e. with the Casamir force), I think it is simply less than or equal to the energy it took to put the apparatus together. Essentially, it's equivalent to sitting in a room with uniform atmospheric pressure and trying to use that atmospheric pressure to do work. You can certainly use a vessle with low or high pressure to do work, but you're never going to get out more energy than it took to create that high (or low) pressure. While one can think about this in terms of thermodynamics, that's really litte more than making concrete the common-sense proposition that you can't get something for nothing. Thus far, nature has not given us any good reason to abandon that idea.

Sometimes people do talk about things like pair creation from the vacuum and the energy-time uncertainty relation, but they are speaking about virtual particles rather than actual particles. The bottom line here is that when you make a measurement, what you will find is actual particles and energy will be conserved, even according to quantum field theory.

As others have noted, the idea of the energy of empty space being nonzero isn't an new idea. The quantum zero-point vacuum energy is nonzero. However, our predictions of its value are ridiculously large, which led some to speculate that either we should redefine the zero point of energy to equal the zero-point energy so that the energy of space exactly equals zero. It's also possible that our ways of doing the accounting are naive (e.g., ignoring quantum gravity), or that some kind of cancellation is going on (e.g. bosons cancelling out fermions in supersymmetry).

This is related to what may be the biggest open question in cosmology, the cosmological constant problem. The energy of space is intimately related to the "cosmological constant". We now know from the accelerating expansion of the universe that there appears to be a nonzero cosmological constant, implying a nonzero vacuum energy. Its experimentally measured value is many orders of magnitude smaller than a naive calculation of zero-point energy based on the Planck scale, however. Another possibility is that the cosmological constant is actually zero, and the accelerating expansion is actually due to the energy/pressure content of some kind of dynamical "dark energy" field (as opposed to the static cosmological-constant form of dark energy).

More on vacuum energy and the cosmological constant, plus a tutorial.

P.S. Contrary to some science fiction applications (cough-StargateAtlantis-cough) and crank physics (cough-Puthoff-cough), you can't extract free energy as work from the zero-point energy. The zero-point energy is by definition the lowest energy state that a system can have; to extract usable energy, you'd have to decrease the energy of the rest of the system below that minimum value, which is by definition impossible.

As others have noted, the idea of the energy of empty space being nonzero isn't an new idea. The quantum zero-point vacuum energy is nonzero. However, our predictions of its value are ridiculously large, which led some to speculate that either we should redefine the zero point of energy to equal the zero-point energy so that the energy of space exactly equals zero. It's also possible that our ways of doing the accounting are naive (e.g., ignoring quantum gravity), or that some kind of cancellation is going on (e.g. bosons cancelling out fermions in supersymmetry).

This is related to what may be the biggest open question in cosmology, the cosmological constant problem. The energy of space is intimately related to the "cosmological constant". We now know from the accelerating expansion of the universe that there appears to be a nonzero cosmological constant, implying a nonzero vacuum energy. Its experimentally measured value is many orders of magnitude smaller than a naive calculation of zero-point energy based on the Planck scale, however. Another possibility is that the cosmological constant is actually zero, and the accelerating expansion is actually due to the energy/pressure content of some kind of dynamical "dark energy" field (as opposed to the static cosmological-constant form of dark energy).

More on vacuum energy and the cosmological constant, plus a tutorial.

P.S. Contrary to some science fiction applications (cough-StargateAtlantis-cough) and crank physics (cough-Puthoff-cough), you can't extract free energy as work from the zero-point energy. The zero-point energy is by definition the lowest energy state that a system can have; to extract usable energy, you'd have to decrease the energy of the rest of the system below that minimum value, which is by definition impossible.

Forgive me for not being up on the details of this, but why do division algebras stop at 8? Does 16 not work?

See Toby Bartels's argument at the bottom of Week 59 of John Baez's TWF series.

Incidentally, the parent poster's argument is wrong. You can construct consistent field theories in N dimensions. Indeed, the division algebras have relevance to why string theory does work in 10 dimensions. (See, for instance, this paper and this comment.

Rate yourself, please. Report your score in another post on this thread. http://math.ucr.edu/home/baez/crackpot.html PS: IAAP

Glass doesn't flow either (except in geologic time scales) http://math.ucr.edu/home/baez/physics/General/Glas s/glass.html http://www.straightdope.com/classics/a1_120.html

Hawking's suggestion has the virtue that we actually have the technology necessary to pursue it. I think there is an even more interesting strategy for human survival that requires a few fundamental breakthroughs (which may not actually be possible) but the result would be more dramatic. It's been known since the sixties that a ramscoop fusion engine has the potential to provide constant 1g accelerated space travel. That is, the acceleration would be the amount needed to provide the equivalent of Earth's gravitational field. Analyzing this motion with the appropriate special relativity framework we get remarkable, almost unbelievable, consequences. You can find the analysis in Misner, Thorne and Wheeler's big blue bible Gravitation in chapter six. Because of time dilation and lorentz contraction such a ship could travel to any point in the visible universe with the shipboard time elapsed being less than the number of years a person could expect to live including the return trip.

The amount of time that would correspondingly elapse on Earth during such a round trip is an example of the twin paradox on steroids. There is a list of cases at this web address. The provocative extreme cases involve billions of years. So even though evolution and geological events would have moved far past the era of man we could send teams to the future which could have the potential to renew our species no matter what events might occur. So you could leave in the 21st century and you (not some distant descendant) could return to Earth hundreds, thousands, millions, or even billions of years in the future. Damn, that theory of relativity implies some unbelievable possibilities due to the geometry of how the universe is put together.

No, I didn't know that.

... Good job, because if we were around we would instantly disintegrate into massless particles of light.

Not sure where this actual quote came from, but it may be incorrect. Light (photons) could ideed have mass, as I believe it does.

http://math.ucr.edu/home/baez/physics/Relativity/S R/light_mass.html

There at least 22 other net-documented places that this occurs. Rolling Uphill Illusion . The 'local' location to my residence is Gravity Hill, PA . These locations are well documented and explained in detail. Furthermore the fifth picture from the top shows where the street has been tagged as well as the starting point.

That's not geekery, that's comedic nonsense.

Undecimber is a real month often used in the Lunar Calendar. You'll find it in many time keeping APIs such as java.util.Calendar and the International Components for Unicode. Anyone who's done even a cursory study of alternate calendars should know that.

*huff* More geekery, indeed!

Replying in one place regarding several responses.

First, the speed of gravity was measured decades ago, inferred by the rate at which the orbits of two neutron stars in a binary pair decayed. The rate of decay agreed exactly with what general relativity predicts due to energy loss via gravitational radiation traveling at the speed of light. The 1993 Nobel Prize was awarded for this work. See this FAQ.

Some poster mentioned Magueijo's work; it is, to put it politely, not well accepted. In point of fact, there is little evidence that the speed of light has changed (although there are some controversial studies), and very little evidence that the speed of light differs from the speed of gravity.

Someone else noted Kopeikin's Jupiter paper, but noted that it was immediately attacked. Well, that's true, and if you read the followup papers, you will see that it is now agreed by pretty much everbody but Kopeikin and co. that what they actually measured was the speed of light. And one of the linked articles noted that while this measurement found 1.06c for the speed of gravity, the error bars were +/- 0.2c, so it means nothing; no measurement of the speed of gravity (or light, or anything else) will give exactly c, what matters is whether the error bars exclude c. Anyway, the "measurement" of the speed of gravity discussed by New Scientist really wasn't a measurement of the speed of gravity.

There has as yet been no direct measurement of the speed of light (although the binary star experiment is regarded as a conclusive indirect experiment); that will have to wait until gravitational waves are detected directly by LIGO or a similar experiment.

It is also worth noting that quantum field theory predicts that gravity and light have to travel at the same speed since they're both mediated by massless particles (photons and gravitons); the same goes for extensions beyond QFT such as string theory. Actually, it's true even classically in any field theory compatible with special relativity.

P.S. In case anyone wants to bring up Tom van Flandern and metaresearch.com, he's a famous Usenet crank; see the above FAQ as well as Steve Carlip's paper on the gr-qc arXiv.org for an explanation.

http://www.cs.ucr.edu/~tkarag/papers/BLINC.pdf
http://guh.nu/projects/ta/safeweb/safeweb.html
http://www.ir.bbn.com/~krash/unpubs/TM1321.pdf
http://www.icir.org/vern/papers/stepping/

I found a link about the timing of the mission.
From the article:

About every 175 years, the outer planets, Jupiter, Saturn, Uranus, and Neptune, are aligned geometrically in such a way as to minimize the trip time and energy required to tour all four. In 1965, Gary Flandro, who was at JPL at the time, pointed out that the next such opportunity would occur in 1976, 1977, and 1978 and designed some Grand Tour gravity-assist trajectories that included an Earth-Jupiter-Saturn-Uranus-Neptune mission.

"I saw seminars on Gutzwiller's work connecting the quantum mechanics of chaotic systems with the Riemann zeta function years ago."

Actually I thought that was THE link between quantum mechanics and Rimann's zeta function.
The folklore I've heard is that Dyson was introduced to Montgomery and asked him what he was doing.
Montgomery then starting explaining his work on the zeta function mentioning some particular equation he had come across at which point Dyson recognized it as an entity appearing in the theory of chaotic qm systems.
anyway, I guess that is also basically what it says in the article only using slightly different words.

In case anyone is VERY interested in this, Snaith's thesis is online at : http://www.maths.ex.ac.uk/~mwatkins/zeta/snaith-th esis.ps.
I also think Baez once mentioned it in his column although I can't find the issue.

PS: I found this account of the tale : http://www.maths.ex.ac.uk/~mwatkins/zeta/dyson.htm .

nonzero rest mass for photons, neutrinos and other things previously considered massless are being explored in theory and experiment. Relativistic energy also is a gravitational charge source.

Non-zero rest mass for neutrinos is a near certainty. Non-zero rest mass for the photon is not considered a serious possiblity. I do not know the gravitational effects of moving a moving mass compared to one at relative rest. If gravity inceased with speed then a fast enough moving object would inevitably collapse to a black hole as it approached the speed of light, no matter the mass.

You got your twin paradox messed up:

http://math.ucr.edu/home/baez/physics/Relativity/S R/TwinParadox/twin_paradox.html

I think we are talking about the same thing.
In the quoted explanation, it stated that in a hard vacuum, it works as described. You yourself and this site: http://math.ucr.edu/home/baez/physics/General/Ligh tMill/light-mill.html explains that.
In a partial vacuum, (evacuated to a pressure of 10-3 to 10-4 (to the minus 3 and 4 respectively) atmospheres), it also works, due to a reaction of the remaining gasses at the edges of the black vane, overpowering the light reaction when in a vacuum.
It's the same physical experiment yet a single variation causes 2 opposite results in rotation.
Interestingly enough, if the lightsail ship would be composed of reflective and absorbative surfaces, it may slow/stop and possibly reverse if it strikes 'dirty' vacuum.

This is the original document without howstuffworks framesets. They don't even show you the original URL until you break out of their frames, those assholes.

Unless you use something smaller than atoms...

Obtaining alcohol from corn/cane sugar (never understood why Americans love getting their sugar from corn, blech!) costs far more in energy to run the harvesting/transport/refining equipment than you get out of the alcohol in the end.

Are you certain about corn?

And cane sugar? Are you saying that Brazil is secretly importing magical free oil or something?

"If something doesn't work first time, invent something imaginary"

This is not the first time in which an existing theory has had a part added (a fudge factor if you will...) to explain an anomalous phenomenon.
Such example include,
1. God
2. The aether
3. The cosmological constant

Each of these ideas have been used at some point to ensure that an existing theory (or foundationless preconceptions) coincide nicely with observation. In each case, they have been refuted at some point in the future.
The idea of modifying the rate of gravitational fall off with distance is not a new idea - back in the 1800s, Airy (If I remember correctly) discovered that if instead of gravity obeying an inverse square relationship, it obeyed an inverse relationship to a different power, the predicted orbit of mercury would fit the observed data. If this was proposed however, there would have been a lesser incentive to look for the more accurate theory that General Relativity provides.
I can't help but think that very rarely does true progress come from simple modifications to existing theory. When theory does not match observation, it is often a new idea entirely that is needed to resolve the problem. A modification to an otherwise elegant idea usually obscures the truth.

If this new theory really does provide highly accurate results, we should ask why and look for the underlying cause of gravity falling off faster than expected, rather be complacent with the introduction of a new constant.

Again, no. Nothing is ever observed to be travelling faster than light. Time dilation causes combined velocities to approach ever closer to c but it can still never be exceeded.

To wit: If you and I are both travelling at 0.75c directly towards each other, I would not perceive you to be travelling 1.5c in relation to me nor vice versa. Specfically, we would perceive each other to be doing ... 0.96c due to our respective time dilations.

Equation for combined velocities (speeds are % of c): (vA + vB) / (1 + vA * vB)

[Source]

Notice that the numerator of that equation is plain old Newton but the denominator adds in the Lorentz transformations gamma factor.

He's talking about this:

http://math.ucr.edu/home/baez/physics/Relativity/S peedOfLight/Superluminal/superluminal.html

And he's right, in that yes, sometimes things CAN appear to be moving faster than light at first calculation. I don't think it would work exactly as he described with an object coming straight at you, however.

Bruce

Time Dilation doesn't actually help much here. You have to accelerate to high speed and deccelerate at the end of the journey. Human beans can handle high accelerations for brief times with few ill affects, but we're talking months here. I suppose if you remain strapped into a squishy chair without having to move around too much then two or three g's might be more reasonable, but I'm pretty sure noone's done the studies.

Anyhoo, I typed "relativistic acceleration" into google, and two clicks later I was here.

It's a little disappointing. A traveller would only get up to 95% of the speed of light before it was time to start deccelerating. For longer trips, however, the effect would be greater.

Not according to the modern usage of the term `mass' in relativity.

> One thing I have often wondered is if an object moves fast enough, could its relativistic mass become so large that it
> would look like a black hole relative to a laboratory frame?

No.

Actually it turns out that by accelerating at a constant rate of 1 g, you could (in principle) cross the known universe in an average human lifetime (as measured in the traveler's frame of reference). This is the result of the relativistic dilation of time. Of course there are practical problems with this, not the least of which is the fact that if you ever return to earth after such a trip, billions of years will have passed here. And it takes a lot of energy to maintain that acceleration for such an extended time.

But if you could overcome the other difficulties of near-light-speed travel (and of interstellar travel in general), then less ambitious trips, such as to stars in our own galaxy, would become possible if we can in fact build a ship with these capabilities. Those other difficulties are significant so maybe we still can't go anywhere, but your comment falls short of explaining why not.

The Relativistic Rocket

http://math.ucr.edu/home/baez/crackpot.html

        1 point for every statement that is widely agreed on to be false.

        2 points for every statement that is clearly vacuous.

        3 points for every statement that is logically inconsistent.

      10 points for each favorable comparison of yourself to Einstein, or claim that special or general relativity are fundamentally misguided (without good evidence).

      10 points for claiming that your work is on the cutting edge of a "paradigm shift".

      30 points for suggesting that a famous figure secretly disbelieved in a theory which he or she publicly supported. (E.g., that Feynman was a closet opponent of special relativity, as deduced by reading between the lines in his freshman physics textbooks.)

      30 points for suggesting that Einstein, in his later years, was groping his way towards the ideas you now advocate.

      40 points for claiming that the "scientific establishment" is engaged in a "conspiracy" to prevent your work from gaining its well-deserved fame, or suchlike.

      40 points for claiming that when your theory is finally appreciated, present-day science will be seen for the sham it truly is. (30 more points for fantasizing about show trials in which scientists who mocked your theories will be forced to recant.)

Louis Savain has been trolling the Usenet sci.physics.* groups for almost a decade now. He personally inspired at least one entry in the infamous Crackpot Index (entry 17). He's known particularly for his profane personal attacks on scientists, which many other crackpots manage to abstain from. You can check out his record on Google Groups, under his own name and others such as "Traveler".

...of the Powerpoint presentation, you can pretty much forget the rest of it. Using the John Baez Crackpot Index, this guy scores pretty highly. His first thought experiment on "transverse red shift" is simply wrong, wrong, wrong.

Certainly the reference to how people "not too long ago" believing the Earth to be flat, therefore means that Einstein is wrong trips my bullshit meter.

Oh, and its Yet Another Paper that attempt to "explain the Pioneer Anomaly" in terms of the author's favorite theory. I'm starting to roll my eyes every time the Pioneer Anomaly comes up, because every time I see it, the actual anomaly is not correctly described, before launching into the most tortuous explanation of bizarre logic ever seen outside of Usenet.

Here's all you need:

Flat Assembler

A list of Free assemblers

MASM32

more on MASM

Webster: The Site to Learn Assembly

Have fun...

Here's all you need:

Flat Assembler

A list of Free assemblers

MASM32

more on MASM

Webster: The Site to Learn Assembly

Have fun...

GR correctly predicts the precession of the orbit of Mercury, which was known at the time. The lack of aether, which on its own is pretty firm evidence SR, was demonstrated in many experiments before and after SR.

The Earth would continue to orbit until the sun visibly disappeared.

I just don't think there exists such a thing as a layman explanation of our understanding of gravity.

I was always frustrated by the absence of a simple answer to 'How does gravity work?'

Why is it always attractive and never repulsive?

It is technically complicated to explain how attractive forces work in quantum field theory by particle exchange. Part of the answer is that quantum particles have phases associated with them, and you sum over all possible ways for a particles to get there via different paths with different phases. Suffice to say, they don't act like little billiard balls running into each other.

Or do you mean "how does it work? how does an object here get pulled towards an object there? what is the connection between them?". In which case you're asking a metaphysical question and I suggest consulting a rabbi, priest or shaman.

Funny you should ask this. Sagan said it in Cosmos, I just read that portion last night. From a quick Google search:
http://math.ucr.edu/home/baez/physics/ParticleAndN uclear/photon_mass.html
http://imagine.gsfc.nasa.gov/docs/ask_astro/answer s/960731.html
http://www.physlink.com/Education/AskExperts/ae180 .cfm
http://www.usatoday.com/weather/resources/basics/w onderquest/photonmass.htm
http://www.ibiblio.org/lunar/school/library/massph ot.html

Most texts I've read state simply that photons have no mass. Those that disucss the topic in depth usually indicate that most phycisists believe that photons do not have mass. Just because someone didn't have the same schooling/texts as you does NOT make them ignorant.

Oh, and for what it's worth, GWB was educated by Yale and Harvard. Too bad he didn't have the benefit of a quality education like one might receive in Texas.

• http://www.space.com/scienceastronomy/generalsci ence/constant_changing_010815.html
• http://math.ucr.edu/home/baez/physics/Relativity/S peedOfLight/speed_of_light.html
• http://www.newscientist.com/article.ns?id=dn6092

Feynman says your an asshole.

http://math.ucr.edu/home/baez/physics/Relativity/S R/mass.html