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Tuesday, 6th November, 2012, 04:37 PM #181
The Great Druid (Lvl 17)
In that you think it presents a biased view favoring Dark Matter?
I have no doubt that any college professor is going to promote his favorite theory over others, as college profs are prone to be quite verbose when going over their primary field of expertise.
So yes, it is possible that some professors are going to hammer on Dark Matter = real, especially if that's what they own published works favor.
But I'd also be wary against saying science professors are close minded and teach close mindedness to their students. While they can be guilty of some myopic hypocrisy, as a general rule, the sciences are known to produce people with more open mindedness than any other demographic of humans on the planet.
that's hyperbole on my part, but there ain't any other degrees that teach a methodology for testing your own ideas (the scientific method).
I have no doubt you can find video lectures that prove your point. Just as Umbran could fiind video lectures that are more open minded. I think a better test would be to audit a bunch of physics courses at top univerities. that's where the top new physicists are being made, and that's where they are or are not getting brainwashed.
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Tuesday, 6th November, 2012, 05:14 PM #182
Defender (Lvl 8)
Quoting away, sometimes out of order....
First, about detection of dark matter:
Let me explain this for our other readers before I respond, since it's clear you've read a lot about dark matter. I should also mention that the wikipedia page on it isn't very good in that it relies on just a few authors (including at least one who is a noted MOND proponent) and doesn't really get at the consensus. The issue is that simulations of the formation of galaxies using plain vanilla dark matter (and other standard assumptions) suggest that dark matter becomes extremely concentrated at the center of galaxies. This is called a cusp. However, observations of some galaxies suggest that there is no cusp, rather that the density tops out at some maximum value. This is the origin of the "cuspy halo problem."
Here's the issue with the problem. First, it's tricky to do observations of dark matter halos (since, you know, dark matter is invisible), and, while people agree that there is no evidence yet of cusps, most observers don't think the observations are good enough to say there is evidence against cusps yet. At least not in all types of galaxies -- small galaxies called dwarfs are typically accepted not to have cusps. But the observational situation for big galaxies, like ours, is far from clear, and there could, in fact, be strong cusps still. On the other side of the coin is that the idea of cuspiness comes from simulations which take millions of CPU hours but do not yet include all the physics. In particular, it's only recently that simulations have started to go beyond just the gravity of dark matter and to add normal matter, which does things like make stars, cool down, etc. This can have different effects on dark matter, which might end up making the dark matter more or less cuspy, depending on exactly what happens. It hasn't been worked out well enough yet.
Tuesday, 6th November, 2012, 05:53 PM #183
Spellbinder (Lvl 16)
My daughter and I have discussed this on many occasions. It's not a matter of merely learning the ideas and theories, especially in theoretical areas, it's a matter of learning where these ideas come from and also on how to evaluate these ideas (i.e. learn how to think). I try to influence her strongly to not only keep an open mind on what she is taught, but find out the reasons behind what she is being taught (who discovered it, how it came about, what competing theories existed, etc.). Being open minded is a bit of a nebulous concept at best, but one that I feel is essential to scientists (considering that she is currently planning to become one).
I see lines of strongly opinionated scientists from many different branches of science on both sides of the global warming topic. If the evidence for mankind's influence on it is even somewhat substantial, how come so many scientists from unrelated branches are declaring a side? There either should only be one side that most of them line up on, or these scientists should say that we don't yet have enough data.
Instead, strong opinions, to the point that they are made public, are formed.
I could conjecture that mathematicians might have more open mindedness than any other demographic of humans on the planet. Course, I would probably be wrong.
The first sign of a broken rule is when someone suggests that the way to stop it is by readying an action.
Wednesday, 7th November, 2012, 02:53 AM #184
A problem in the original discussion space (time travel) is that we really are asking the wrong question first: Not, is time travel possible, but, what would it look like it was possible? That is, at a fine, measurable, level, what would we see if time travel were actually happening?
Why this is important is because folks are talking about the possibility of time travel without figuring out the basic consequences.
As an example, there is an interesting device in Baxter's Time Ships. I don't remember what they called it in the book, so I'll just call it Plattnerite Pool. What you have is a pool table fitted with time machines in the pockets. A ball dropped into a pocket travels back in time a few seconds or perhaps a minute, then is spat out of a different pocket.
If time travel of a form allowing travel to one's own past is possible, then Plattnerite Pool is possible, at least from a particle interaction point of view, if not as an actual pool table.
If such a device were available, and one had a chance to play with it for a while, the question arises as to what would be the stable behavior of the table? A globally consistent behavior must arise as a fixed point from the physics and one's interaction with the device. What possible behavior is there?
As an example: A ball is placed on the table near one corner. Waiting for a minute or so, a ball appears on the far side of the table, rolls forward to display the first ball, then slowing to take the first ball's place. The first ball rolls into a pocket and disappears with a flash.
Upon examination, the second ball is seen to be identical, in all ways, to the first ball, except having two very slight smudges where the ball structk itself.
This example would perhaps be impossible: There is a causal loop with no initial cause.
As a second example, one decides to do the simplest experiment, and push a ball into a pocket. One approaches the table, watches satisfyingly as a ball appears out of one of the pockets at the predicted time, then deposits the ball (in hand) into a pocket.
As a third example, one is clever and decides to mix up the experiment. Pocket A goes to Pocket C while Pocket B goes to pocket D. One decides to drop a ball into pocket A if the ball is seen to appear in pocket D, and to drop a ball into pocket B if the ball is seen to appear in pocket C. What happens? Does a ball ever appear?
Wednesday, 7th November, 2012, 03:38 AM #185
Wednesday, 7th November, 2012, 03:47 AM #186
Hydra (Lvl 25)
It is imaginable that we live in a universe where time travel is not strictly prohibited, but that it can be used in such ways that actually destroy the cosmos.
Wednesday, 7th November, 2012, 04:22 AM #187
Enchanter (Lvl 12)
Wednesday, 7th November, 2012, 04:27 AM #188
Thaumaturgist (Lvl 9)
Wednesday, 7th November, 2012, 04:32 AM #189
Enchanter (Lvl 12)
Watching a prerecorded lecture online is to sitting in a real classroom, with a real instructor, as watching online porn is to actually having sex. If that's good enough for you, then so be it, but it's not even close to the same.Actually, Stanford has several grad school level lectures online. There are also free classes online from a few top universities. A guy I work with sometimes takes these and I have been considering the idea.
Wednesday, 7th November, 2012, 02:56 PM #190
The Great Druid (Lvl 17)
They just weren't getting it, and merely parrot or calculate their way through the material, without really grasping it.
NPR had an article with a physics prof from standford or one of those big schools where he talked about the problem. One of the things he realized was that the way a 20 year physics veteran explains a concept he has undertstood forever to a student is not the same as how a fellow student who just "figured it out" will do so.
So, he changed up his teaching to present a concept, have the students work out a problem, and then have the students talk and self-correct as the kids who figured it out correctly transmit way of thinking to the rest of the students.
In any case, I'm still wary that a video of a lecture shows the whole picture on interaction with a professor or even fellow students.
There are always scientists who stick to their theory, and belittle other theories. Archaeology has the same problem, when some scientist has proof that the presuumed chain of evolution happened differently due to his new fossil.
But, the sciences as a whole, tend to produce people who do tend to change their mind.
As opposed to people who think the world is only 6000 years old. Those people will die holding that belief their entire lives. Since humans as a general rule, tend to NOT be able to change their beliefs, scientists are downright openminded as a subset of the human demographic.
You can also probably test this by reviewing the public record on each scientist and see if they later change their position on something the rest of the science community disproved. I suspect, you will find that most scientists do shift their position as new information is discovered, though they may cling to certain areas more tenaciously than others.