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Einstein's Theory Improved?
skaet writes to tell us that A Chinese astronomer from the University of St Andrews claims to have fine-tuned Einstein's theory of gravity. Dr Hong Sheng Zhao has created a 'simple' theory which could "solve a dark mystery that has baffled astrophysicists for three-quarters of a century." This new law seeks to discover whether Einstein's theory was correct and if dark matter actually exists.
What a clear and well-written article. And what a pleasant, unassuming statement from Dr Zhao:
"A non-Newtonian gravity theory is now fully specified on all scales by a smooth continuous function. It is ready for fellow scientists to falsify. It is time to keep an open mind for new fields predicted in our formula while we continue our search for Dark Matter particles."
Even if the theory turns out not to stand up, words like this take us back to what makes science interesting and important. That "falsify" is worlds away from the publicity hounds and egomaniacs who so often represent science to the lay reader.
Las qué passoun
tournoun pas maï
Yes, most is actually transparent. There are many particles that don't interact with photons. They don't emit or absorb light, so therefore are impossible to detect with light and they can't block light either. A small percentage of dark matter is thought to be 'normal' matter that does reflect light, but the universe is big and not so bright. It's rare to get a chunk of rock or ball of gas reflecting much light in our direction. Astronomers have a hard time detecting planets many times larger than Jupiter
For the reasons why dark matter must exist; some reasons are straight forward, some are more round-about-observations. The easiest one is from galaxies rotating too fast. The fact that they stay together means something is holding them together. Since we don't observe anything like a giant rope or hand of God holding our sun in place, the only logical explanation is gravity. Since we can't see enough matter to make this much gravity, it must be dark.
The dark matter that's hypothesized because of the large scale curvature of the universe is not as straight forward, especially since it was recently found that the universe seems to be accelerating in it's expansion.
I'd also like to point out that gravity, electrons and other particles or forces are no less valid than photons as observational tools. We really don't have to 'see' something to know it's there.
Side-tracked into a religious flamewar withing 2 posts. That's got to be a first, even for slashdot.
Just because you're paranoid doesn't mean there isn't an invisible demon about to eat your face
Cole's law - delicious!
Vintage computer adverts: http://www.vintageadbrowser.com/computers-and-software-ads
As a side note, the "ancient language" remained very consistant for a very long time. There is very little difference between the hebrew spoken then versus now. Only when you get far enough in the past to aramaic (spelling??), you get an actual different language.
First off, I want to say a few words about dark matter. I think it's kind of irritating when people rant on about how dark matter is ad hoc fudging, etc. etc. Well, "fiddling around with the laws of gravity" isn't any better on that account. The fact of the matter is that all of theoretical physics is creating new models that fit our observations, and both dark matter and MOND fall into that category. The very existence of MOND as a theory shows that it is not easy to distinguish "matter that primarily interacts gravitationally" from "modifications to the laws of gravity". Historically, both "unseen matter" and "modifications to gravity" have been valid solutions to anomalous gravitational behavior (in the cases of Neptune's orbit and the perihelion precession of Mercury, respectively).
As it stands, dark matter models can pass many experimental tests, and they're still the way to bet. That being said, MOND is not a bad idea either. It's not as well supported by dark matter, and it has serious problems with galaxy clusters, but it can still account for a surprising amount of data (for a nonrelativistic theory!). The flaw of non-relativistic has been "corrected" by Bekenstein's TeVeS theory (the one that Zhao and Famaey's work is based on).
Unfortunately, TeVeS appears to be rather ad hoc (even compared to dark matter). Z&F's work does not appear to be much better in this regard. In addition, solar system observations appear to place serious constraints on such MOND-like theories, leading to anomalous non-inverse square forces in the outer solar system (and no, it doesn't seem to be of a form that can be attributed to the Pioneer anomaly, though the jury is still out).
The TeVeS/dark matter debate should be definitively resolved by the Planck mission, which will be capable of resolving the third acoustic peak in the the cosmic microwave background radiation power spectrum. TeVeS and dark matter make very different predictions for the structure of this peak. Of course, if TeVeS fails this test, maybe some other MOND-like theory could be put forward (if the entire class of theories hasn't already been ruled out by other means, such as solar system dynamics, by then).
A word about semetic languages like Hebrew, Arabic, and Amaharic: they have a rich infix morphology. What this means in practice is that various inflections of Hebrew words (an English example of inflection is the addition of -s to the end of a verb in the third person, for example, I say versus he says) involve swapping the vowels in a word (but the consonants stay the same).
Indeed, most verbs in Hebrew have a three consonant "root" (some have two). Depending on the tense, person, number, and gender of a verb (Hebrew verbs, unlike say, French verbs, agree with the subject's gender as well as number), the vowels in a Hebrew verb will change (and a prefix or suffix may be added as well).
All of this is just a roundabout way of saying that any word with say, a k-t-v root will have to do with, in this case, writing, whether it's katav or kotev or what have you.
This is why all semetic languages evolved writing systems where the vowels are generally not written: vowels simply don't have much semantic value in semetic languages. It may seem weird at first, but it's actually rather logical if you're exposed to it for a while.
Now, I'm not Jewish, so I don't know exactly, but I remember reading that the religious texts in fact were marked with the vowel diacritics -- that in fact, the vowel diacritics were invented for the sole purpose of reminding Rabbis how the texts should be read, as Hebrew was a dead language for a millenium or more.
Native speakers have little need for them, as it is clear from context what the vowels should be. Thnk abt t, vn n nglsh y cn ndrstnd lrght, and in English the presence or absence of vowels can actually change the root meaning of a word!
Anyone who is actually Hebrew-speaking and/or Jewish feel free to correct me. My Hebrew is very bad.