251. Large Hadron Collider readies for world's biggest experiment
Comment #243226 by Oystein Elgaroy on September 5, 2008 at 10:00 am
Q: Does mini-black hole means a there would be a mini-event horizon?
252. Large Hadron Collider readies for world's biggest experiment
Comment #243220 by Oystein Elgaroy on September 5, 2008 at 9:54 am
Comment #243201 by Dhamma
Could this have any impact at all on believers to question their faith?
Depending on what's found, of course.
253. Pakistan investigates 'honor killings' of 5 women
Comment #241407 by Oystein Elgaroy on September 2, 2008 at 7:33 am
Comment #241394 by decius
It's just out of respect for your present conditions that I don't unleash Oystein and set him on you.
254. Cosmic crash unmasks dark matter
Comment #241166 by Oystein Elgaroy on September 1, 2008 at 10:53 pm
Comment #241014 by Apathy personified
Does this come down to Einstein being wrong about the cosmological constant (when he said it didn't exist), or there being a small error in GR, that is only noticable on very large distances?
255. Cosmic crash unmasks dark matter
Comment #241163 by Oystein Elgaroy on September 1, 2008 at 10:45 pm
Comment #241045 by debacles
You are right, the dark matter interacts. Since it emits no detectable electromagnetic radiation (that's why it is dark) it must be some kind of neutral particle with no electromagnetic interactions. If it is a WIMP (Weakly Interacting Massive Particle) it couples to other particles with the strength of the weak nuclear force (the one responsible for e.g. beta decay of nuclei). "Massive" here means a few hundred times the mass of the proton. One can show that a particle with these properties will be produced in the early universe and end up giving a contribution to the mass density of the universe of just about the right magnitude to make up the dark matter.
The dark matter interacts through gravitation as well, of course, just like any other particle. Otherwise it would, as you rightly remark, have been pretty useless.
256. Cosmic crash unmasks dark matter
Comment #240990 by Oystein Elgaroy on September 1, 2008 at 11:38 am
Apathy,
The cosmological constant can, sadly, not be derived. There was for some time a hope that it could be derived in string theory, but what we seem to be left with is the string landscape and the anthropic principle.
We cannot discount a long-range fifth force if it couples weakly to matter on small scales (solar system and below). But then you would have a new fine-tuning problem: why should this scalar field couple so weakly to matter? The chameleon mechanism solves this problem by making the coupling depend on the local matter density.
257. Cosmic crash unmasks dark matter
Comment #240974 by Oystein Elgaroy on September 1, 2008 at 11:09 am
Comment #240971 by Naturalist1
I agree...that which, at the time Einstien called his greatest blunder may in fact have been his greatest genius insight...LHC may let us know.
258. Cosmic crash unmasks dark matter
Comment #240933 by Oystein Elgaroy on September 1, 2008 at 10:08 am
Sorry for the Joe Morreale-length of this post.
Comment #240865 by Ian Bamlett
Thanks! I consider it part of my job. It is the only way I can excuse all the time I spend on this site ![]()
Comment #240879 by Apathy personified
What are the leading theories on dark energy? I haven't actually heard or read about any (although that is probably more a reflection on my own ignorance)
259. Cosmic crash unmasks dark matter
Comment #240823 by Oystein Elgaroy on September 1, 2008 at 5:30 am
Comment #240820 by Ian Bamlett
There is no necessary connection between dark matter and extra dimensions. All we need is a new, weakly interacting particle. There are some more inventive models where the effects we ascribe to dark matter are caused by our universe interacting with another "dark universe" via a fifth dimension. They are fun, but my money is on the dark matter being one of the WIMPs found in supersymmetric extensions of the Standard Model.
What is really exciting about dark matter is that it is a clear signature of new physics. To explain the observations we must either introduce a new particle, or we must modify general relativity.
260. Cosmic crash unmasks dark matter
Comment #240790 by Oystein Elgaroy on September 1, 2008 at 3:43 am
Comment #240780 by decius
They can't, this is part of the assumption they are testing here. The observable matter in galaxy clusters is dominated by hot gas emitting X-rays, but most of the matter is expected to be dark matter. Picture the two galaxy clusters as two spherical blobs of matter. When the collide, the gas components will interact with each other and there will be a concentration of it in the collision region. The dark matter in the two blobs will just pass freely past each other. After quite some time what you will be left with is two intersection blobs of matter where the hot gas is concentrated in a small region of overlap whereas most of the dark matter will be found outside of this region. X-ray observations can tell you where the gas is, and observations of how the two clusters distort the images of background galaxies allow you to map out the gravitational field of the cluster and hence where most of the mass is. The fact that the observations agree with the simple picture above suggests that the dark matter indeed is some kind of weakly interaction particle.
261. Cosmic crash unmasks dark matter
Comment #240766 by Oystein Elgaroy on September 1, 2008 at 2:52 am
Regarding WIMPS vs MACHOS the odds are in favour of WIMPS. As mentioned in the article, MACHOS are built from ordinary baryonic matter. Models and observations of the synthesis of light elements in the early universe , and the temperature variations in the cosmic microwave background tell us that the contribution of baryons to the total energy density is only about four percent. At the same time both the microwave background and studies of how structure formed in the universe show that the total contribution from matter to the energy budget is about 25 percent. So most of the dark matter has to be non-baryonic, and the favourite candidate is one of the heavy, weakly interacting particles predicted to exist in extensions of the Standard Model of particle physics.
262. Atheists: The Last Political Outcasts
Comment #240355 by Oystein Elgaroy on August 31, 2008 at 11:39 am
Comment #240350 by Quine
You may already have read it, but "C.S. Lewis and the search for rational religion" by John Beversluis is a very good book-length refutation of Lewis.
263. A flea we missed?
Comment #239842 by Oystein Elgaroy on August 30, 2008 at 12:22 pm
David R,
I am still waiting for your comments on Acts 5.
are you saying that Penzias was unfamiliar with physics (perhaps he won the Nobel prize for gardening?!) or the Bible?
264. Ayaan Hirsi Ali & The Big Ideas Forum
Comment #239680 by Oystein Elgaroy on August 30, 2008 at 7:40 am
Comment #239677 by SilentMike
I am not sure. At least she seems to think that one should "teach the controversy".
265. Ayaan Hirsi Ali & The Big Ideas Forum
Comment #239675 by Oystein Elgaroy on August 30, 2008 at 7:13 am
Comment #239668 by Bonzai
Who is that? Sorry, haven't been following the American election dramas lately.
266. Genesis and the origin of the Origin of the species
Comment #239586 by Oystein Elgaroy on August 30, 2008 at 1:04 am
This argument figures nowhere in the Hebrew Bible.
267. Atheism could be science's contribution to religion
Comment #239425 by Oystein Elgaroy on August 29, 2008 at 2:37 pm
From personal experience I would say that the TF has very little influence within the scientific community. I would bet most of my colleagues have never even heard of it. And the Templeton prize has as far as I know never been awarded for the kind of work that is considered serious science. The battleground is really the public perception of the relationship between science and religion, and I am sure the TF has done some damage in that respect. I don't think it is a coincidence that many of the winners of the Templeton prize are well-known writers of popular science books like, e.g., Paul Davies and John Barrow.
268. Why Dawkins is right and his critics are wrong
Comment #235970 by Oystein Elgaroy on August 24, 2008 at 1:19 am
Comment #235907 by thewhitepearl
- Sound barriors/waves, the left over existence of what cosmology explains as the big bang, something about proof of how EVERYTHING in the universe is spoken into existence.
269. Black holes 'dodge middle ground'
Comment #235191 by Oystein Elgaroy on August 22, 2008 at 2:17 pm
Comment #235177 by ridelo
I forgot to mention that black holes usually spin. The star can gain energy by tapping the rotational energy of the black hole.
270. A flea we missed?
Comment #235180 by Oystein Elgaroy on August 22, 2008 at 2:02 pm
Comment #235173 by David A Robertson
Anyway time to go for another week....I suspect this thread has run its course - going by the degeneration of the last couple of pages but if there is anything interesting, in the words of Arnold 'I'll be back'.
Meanwhile I leave you with my most delightful moment on RD net for weeks - the Milliband thread and the pathetic attempts to square the following circle.
271. Black holes 'dodge middle ground'
Comment #235172 by Oystein Elgaroy on August 22, 2008 at 1:50 pm
The way I understand it, the only difference between a small and large one is that the big one has more matter to suck at its inception(is that a word?).
272. A flea we missed?
Comment #235170 by Oystein Elgaroy on August 22, 2008 at 1:45 pm
Comment #235158 by David A Robertson
The basic principles are that you read the Bible according to context, genre and literary type. There is poetry, history, apocalyptic, law and prophecy.
273. Black holes 'dodge middle ground'
Comment #235143 by Oystein Elgaroy on August 22, 2008 at 1:24 pm
Comment #235137 by debacles
All black holes are stable (except for Hawking radiation which is negligible except for microscopic black holes). They are basically saying that we don't understand the details of how star clusters form and evolve.
But black holes can start off large. Huge density perturbations in the young universe could collapse and form black holes with masses between a few hundred thousand and a few million solar masses.
274. Black holes 'dodge middle ground'
Comment #235130 by Oystein Elgaroy on August 22, 2008 at 1:03 pm
Comment #235104 by debacles
"Small" and "large" refer to the black hole's mass. But the radius (Scharwzschild radius) of a black hole is proportional to the mass, so it is also says something about geometrical size. The strength of the gravitational field is, of course, also related to the mass. However, should you be so unlucky as to fall into a black hole, a large one is much to prefer as it is the tidal forces that kill you in the end, and these are weaker around a large black hole. You die in the end no matter what, but at least you have time to have a look at the interior if the black hole is really huge. The supermassive black holes that lie in the center of most galaxies have grown larger over billions of years by swallowing nearby stars and gas.
Comment #235113 by NewEnglandBob
If a small black hole (or any kind of object) passes near a large black hole, but not near enough to be pulled in, it will be accelerated in the gravitational field and this may give them enough speed to escape from the cluster. The same effect is used on a less dramatic scale to give satellites that are sent to the outer part of the solar system an extra boost by letting them pass by, e.g., Jupiter.
Medium-sized black holes are expected to exist. That is why the results referred to in the article are puzzling.
275. Black holes 'dodge middle ground'
Comment #234953 by Oystein Elgaroy on August 22, 2008 at 9:53 am
The paper is available at
http://arxiv.org/abs/0805.2952
276. The rise of Miliband brings at last the prospect of an atheist prime minister
Comment #234740 by Oystein Elgaroy on August 22, 2008 at 1:03 am
Like everybody here I am getting tired of the "Stalin was an atheist" argument. Yes, he was an atheist, but he also believed in a marxist utopia waiting at the end of history and that any means were justified in order to help history along to that goal. This belief was not based on any evidence and I am tempted to classify it as religious.
277. A flea we missed?
Comment #234237 by Oystein Elgaroy on August 21, 2008 at 3:11 am
Comment #234229 by Quetzalcoatl
By this logic, it is good that Swinburne exists since it gives people something to laugh and point at.
278. A flea we missed?
Comment #234228 by Oystein Elgaroy on August 21, 2008 at 2:46 am
Comment #234201 by Quetzalcoatl
Funny how theology's attempts to explain away problems with God always end up raising fresh issues.
279. A flea we missed?
Comment #234178 by Oystein Elgaroy on August 21, 2008 at 12:02 am
Comment #233911 by NMcC
Any thoughts on an omniscient being who's spectacularly bad at predicting the results of His own actions?
280. A flea we missed?
Comment #233778 by Oystein Elgaroy on August 20, 2008 at 11:58 am
Comment #233774 by decius
I wanted to bring that episode up because it illustrates quite clearly that the moral princples inherent in the New Testament are just as questionable as those in the Old Testament.
281. A flea we missed?
Comment #233756 by Oystein Elgaroy on August 20, 2008 at 11:33 am
This thread certainly provides a lot of reading material. I would be very interested in a more detailed explanation of how DR thinks scripture should be interpreted. Are there any firm principles that can tell you what is to be taken literally?
Another, and slightly related, matter: Among Christians the early Jerusalem church is often considered an ideal for how society should be organized. One of the few insights, if accepted as historical, into how things work is found in Acts 5. Is the punishment meted out to Ananias and Sapphira proportioned to their crime? Is this a good example to modern Christians?
282. No credit for creationism
Comment #233454 by Oystein Elgaroy on August 20, 2008 at 12:29 am
Comment #233412 by Greyman
PS: Big Bang Theory also predicts things like: distant object will appear brighter than they would if space were not curved. This is not observed, causing cosmologists to rexamine the theory, and some to propose alternative models.
283. A flea we missed?
Comment #233084 by Oystein Elgaroy on August 19, 2008 at 5:30 am
Comment #233075 by Steve Zara
Judging by his earlier books like, e.g., "The Mind of God", Davies has some sympathy for mysticism, but he is not a theist.
284. A flea we missed?
Comment #232513 by Oystein Elgaroy on August 18, 2008 at 8:41 am
Comment #232510 by Steve Zara
I have read "The Goldilocks Enigma". It is a bit , shall we say, imaginative at times, but I was never under the impression that Davies was arguing for theism. If Robertson says so he a) hasn't read the book or b) hasn't understood a word of it or c) lies in the hope that his readers haven't read Davies' book.
285. A flea we missed?
Comment #232477 by Oystein Elgaroy on August 18, 2008 at 7:32 am
Comment #232472 by irate_atheist
This is closer to home. With a student I am working out the cosmological implications of Adams' paper.
He didn't bother to check whether stars could form at all in his universes, so that is what we are trying to work out.
286. A flea we missed?
Comment #232470 by Oystein Elgaroy on August 18, 2008 at 7:13 am
Comment #232462 by Vaal
EDIT: Haven't heard him bringing up Oystein's credentials yet.
287. Do subatomic particles have free will?
Comment #232002 by Oystein Elgaroy on August 17, 2008 at 12:07 pm
Steve, Sargeist,
I stand corrected.
288. Do subatomic particles have free will?
Comment #231980 by Oystein Elgaroy on August 17, 2008 at 11:40 am
Really, I find this interesting as it was my (admittedly naive) perception that locality was still a "requirement" in the minds of most physicists.
289. Do subatomic particles have free will?
Comment #231972 by Oystein Elgaroy on August 17, 2008 at 11:31 am
Comment #231964 by Sargeist
Thanks for digging out the papers!
290. Petrol pump pilgrims keep faith
Comment #231895 by Oystein Elgaroy on August 17, 2008 at 9:29 am
If I were the owner of a gas station I think I would be willing to drop the price by 5 percent to get rid of a bunch of nutcases who might very well scare other customers away.
291. A flea we missed?
Comment #231863 by Oystein Elgaroy on August 17, 2008 at 8:16 am
Comment #231857 by Vaal
Here is a quote from Rocky Kolb's "Blind watchers of the sky":
"As an astronomer king Tycho had a court of sorts, and Jepp was his buffoon. Jepp was a person who stood up and looked Tycho squarely in the knees - a dwarf whom Tycho treated more as a pet than as a person. During dinners at Uraniborg, Jepp would sit under the table at the feet of the astronomer king begging for food, and occasionally Tycho would toss a scrap of food under the table for his buffoon."
292. A flea we missed?
Comment #231850 by Oystein Elgaroy on August 17, 2008 at 7:35 am
Comment #231847 by Apathy personified
Newton was such a character, definately on the 'crazy side' of genius though.
293. A flea we missed?
Comment #231839 by Oystein Elgaroy on August 17, 2008 at 7:19 am
Comment #231833 by Apathy personified
Didn't Newton have to keep hold on the principia because he was in an isolated village during the plague?
294. A flea we missed?
Comment #231825 by Oystein Elgaroy on August 17, 2008 at 6:49 am
Comment #231816 by Corylus
The way some people take note of Newton's genius and christianity (but keep very quiet concerning his other interests) you would be forgiven for thinking that his works on astrology had been found under his bed along with a half-eaten sandwich and a copy of Spanking Nuns Monthly.
295. A flea we missed?
Comment #231822 by Oystein Elgaroy on August 17, 2008 at 6:42 am
Comment #231811 by Cartomancer
Actually, by the time he was in his thirties (he'd published the Principia when he was my age, as if I needed to feel any more inadequate than I already do!)
296. A flea we missed?
Comment #231567 by Oystein Elgaroy on August 16, 2008 at 2:51 pm
Comment #231554 by decius
Finally king Harald shows some good sense. I have never been a fan of the monarchy, but now I will have to think again.
297. A flea we missed?
Comment #231551 by Oystein Elgaroy on August 16, 2008 at 2:25 pm
Comment #231540 by mordacious1
That is a wonderful title. You should write that book.
298. A flea we missed?
Comment #231531 by Oystein Elgaroy on August 16, 2008 at 1:51 pm
Does anyone know why it is that Richard and Sam each have lots of flea books, but Christopher Hitchens doesn't?
299. Enemies of Reason: Available now on DVD!
Comment #230995 by Oystein Elgaroy on August 15, 2008 at 2:06 pm
Durant -
There are no logical arguments that Professor Bigot has offered for atheism
300. We need to stop being such cowards about Islam
Comment #230138 by Oystein Elgaroy on August 14, 2008 at 10:42 am
Comment #230116 by PJG
Christians I have met say that the meaning of that passage from Matthew is that Jesus was the fulfillment of the law in the OT, and that they are therefore no longer bound by it.