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#271




Neil DeGrasse Tyson headed down same loony road as Carl Sagan?
On Tue, 09 Oct 2018 07:46:14 0600, Chris L Peterson
wrote: On Tue, 09 Oct 2018 15:21:57 +0200, Paul Schlyter wrote: Why? That's a fallacy. GR is easy to understand. QM is easy to understand. That doesn't make either of them obvious. We can puzzle for a long time over a tricky problem that ends up having an extremely simple and easy to understand solution. Simple != obvious. Here you contradict yourself by saying: 1. QM and GR are both simple.. 2. Simple is obvious. 3. However, QM and GR are not necessarily obvious. Where did I say that simple is obvious? I said that simple does not imply obvious. OK, I misread your != as a = However, simple != obvious is also in error because it implies that anything which is obvious also must be complex. That is not the case. 
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#272




Neil DeGrasse Tyson headed down same loony road as Carl Sagan?
On Wednesday, October 10, 2018 at 12:29:38 AM UTC6, Paul Schlyter wrote:
Which frequency range is that? And is thar radio waves or infrared? Terahertz radiation. Those naked airport scanners. Higher frequency radio waves than microwaves. John Savard 
#273




Neil DeGrasse Tyson headed down same loony road as Carl Sagan?
On 10/10/2018 07:29, Paul Schlyter wrote:
On Tue, 9 Oct 2018 14:36:12 +0100, Martin Brown wrote: It is the awkward gap where photon energy is too low for optical devices and frequency too high for microwave techniques to work adequately. Which frequency range is that? And is thar radio waves or infrared? Its in the crossover between mm microwaves and far far infrared. Roughly 1THz /* 5 or so depending on who you talk to is the tricky bit. http://www.teraview.com/about/whati...hertzthz.html It is all the rage for nondestructive testing with nonionising radiation now that bright emitters are available (for a price). When I was a radio astronomer we could operate up to 31GHz limited by baseline surveying and surface roughness as well as the availability of LNB and down converters for the front end. VLA could go slightly higher at up to 50GHz. It is a fair bit higher now. Today there are some exotic devices capable of detecting signals almost up to 1THz. ALMA in the Atacama desert is capable of observing at frequencies from 31GHz up to 950GHz (although I expect it is pretty ropey at the highest end). It is a nominal terahertz instrument (just). There are a few precision single dishes about too. The surface has to be a very good parabolic mirror finish for the system to form good images. And coherent focal plane cameras to go with them with as many as 100 pixels (they are aiming for 1000)! https://www.nrao.edu/meetings/isstt/...2011179000.pdf  Regards, Martin Brown 
#274




Neil DeGrasse Tyson headed down same loony road as Carl Sagan?
On Wed, 10 Oct 2018 08:34:40 +0200, Paul Schlyter
wrote: I have not argued anywhere that it is simple to find any answers. You have a quite unusual definition of simple if you think e.g. tensor calculus is simple. Yes, the GR theory uses tensor calculus as an essential part. Well, in truth, tensor calculus IS simple. That is, it requires nothing more than following a set of rules. That's why problems are readily solved by computers. But that's irrelevant to my point. The laws of nature are simple. GR is simple. That doesn't require that everyone somehow has the ability to utilize the tools used to solve problems. In normal language use, simple implies easy to learn. That's a very limited use. 
#275




Neil DeGrasse Tyson headed down same loony road as Carl Sagan?
On Wed, 10 Oct 2018 08:38:41 +0200, Paul Schlyter
wrote: On Tue, 09 Oct 2018 07:46:14 0600, Chris L Peterson wrote: On Tue, 09 Oct 2018 15:21:57 +0200, Paul Schlyter wrote: Why? That's a fallacy. GR is easy to understand. QM is easy to understand. That doesn't make either of them obvious. We can puzzle for a long time over a tricky problem that ends up having an extremely simple and easy to understand solution. Simple != obvious. Here you contradict yourself by saying: 1. QM and GR are both simple.. 2. Simple is obvious. 3. However, QM and GR are not necessarily obvious. Where did I say that simple is obvious? I said that simple does not imply obvious. OK, I misread your != as a = However, simple != obvious is also in error because it implies that anything which is obvious also must be complex. That is not the case. I think my meaning was pretty clear, that "simple" and "obvious" are not synonyms. Sure, there are simple things which ARE obvious. But nothing requires that things which are simple are also obvious. The reason it has taken us thousands of years to figure out most of nature is precisely because all those simple rules are not obvious. 
#276




Neil DeGrasse Tyson headed down same loony road as Carl Sagan?
On 10/10/2018 14:19, Chris L Peterson wrote:
On Wed, 10 Oct 2018 08:34:40 +0200, Paul Schlyter wrote: I have not argued anywhere that it is simple to find any answers. You have a quite unusual definition of simple if you think e.g. tensor calculus is simple. Yes, the GR theory uses tensor calculus as an essential part. Well, in truth, tensor calculus IS simple. That is, it requires nothing more than following a set of rules. That's why problems are readily solved by computers. You have a *very* strange definition of simple. Most postgraduate mathematics students struggle to visualise the true meaning of covariant and contravariant derivative tensors in a curved metric space. Even Newtonian dynamics quickly becomes computational solutions only for the three body problem unless you have a very rare stable closed form. But that's irrelevant to my point. The laws of nature are simple. GR is simple. That doesn't require that everyone somehow has the ability to utilize the tools used to solve problems. The inverse square laws for gravity and electromagnetism are relatively simple but the dynamics of objects moving under them is not even for three self gravitating bodies. I am not so sure about the layer that sits underneath QCD  I never did like HEP though. I found the arbitrary use of renormalisation to get rid of unwanted infinities a little bit worrying  it worked OK provided that you knew what you were doing. In normal language use, simple implies easy to learn. That's a very limited use. You can describe GR in a simple way as matter curving straight lines in spacetime but to use it in anger requires very high level mathematics that is typically not taught at undergraduate level except at a handful of institutions. By any reasonable definition that makes it not simple.  Regards, Martin Brown 
#277




Neil DeGrasse Tyson headed down same loony road as Carl Sagan?
On Wed, 10 Oct 2018 16:26:47 +0100, Martin Brown
wrote: On 10/10/2018 14:19, Chris L Peterson wrote: On Wed, 10 Oct 2018 08:34:40 +0200, Paul Schlyter wrote: I have not argued anywhere that it is simple to find any answers. You have a quite unusual definition of simple if you think e.g. tensor calculus is simple. Yes, the GR theory uses tensor calculus as an essential part. Well, in truth, tensor calculus IS simple. That is, it requires nothing more than following a set of rules. That's why problems are readily solved by computers. You have a *very* strange definition of simple. Most postgraduate mathematics students struggle to visualise the true meaning of covariant and contravariant derivative tensors in a curved metric space. Even Newtonian dynamics quickly becomes computational solutions only for the three body problem unless you have a very rare stable closed form. I would describe as "simple" in the context I'm talking about here anything which has a computational solution. But that's irrelevant to my point. The laws of nature are simple. GR is simple. That doesn't require that everyone somehow has the ability to utilize the tools used to solve problems. The inverse square laws for gravity and electromagnetism are relatively simple but the dynamics of objects moving under them is not even for three self gravitating bodies. I didn't say that behavior is simple. I said that the rules are simple. Simple rules can certainly lead to complex behavior, which may be difficult or even impossible to predict. You can describe GR in a simple way as matter curving straight lines in spacetime but to use it in anger requires very high level mathematics that is typically not taught at undergraduate level except at a handful of institutions. By any reasonable definition that makes it not simple. I disagree. It is simple by virtue of the fact that it is subject to known rules that can be reliably and consistently applied to describe the behavior of nature. The nature of the math is irrelevant. 
#278




Neil DeGrasse Tyson headed down same loony road as Carl Sagan?
On Wed, 10 Oct 2018 10:06:57 0600, Chris L Peterson
wrote: I disagree. It is simple by virtue of the fact that it is subject to known rules that can be reliably and consistently applied to describe the behavior of nature. The nature of the math is irrelevant. So in your world, known rules which are complex does not exist? 
#279




Neil DeGrasse Tyson headed down same loony road as Carl Sagan?
On Wed, 10 Oct 2018 18:19:01 +0200, Paul Schlyter
wrote: On Wed, 10 Oct 2018 10:06:57 0600, Chris L Peterson wrote: I disagree. It is simple by virtue of the fact that it is subject to known rules that can be reliably and consistently applied to describe the behavior of nature. The nature of the math is irrelevant. So in your world, known rules which are complex does not exist? I don't know of any natural laws that I would characterize as complex, no. 
#280




Neil DeGrasse Tyson headed down same loony road as Carl Sagan?
The centrepiece of astrophysics is certainly the socalled 'inverse square law' which appeared to give legs to the idea that experimental sciences scale up to planetary dynamics. The fact that it wasn't a law in Kepler's proposal doesn't seem to deter the empiricists from making it that way but then again, this is the way academics have operated for centuries.
The statement from Kepler first appears daunting and is probably unhelpful as it distracts from the nuts and bolts of observations tied to variable orbital speeds where he was most effective  "The proportion existing between the periodic times of any two planets is exactly the sesquiplicate proportion of the mean distances of the orbits, or as generally given,the squares of the periodic times are proportional to the cubes of the mean distances." Kepler In a gentler light and a more expansive explanation, it is easy to see he is equalising observations in speeds and distance from the Sun rather than explaining orbital motions  "But it is absolutely certain and exact that the ratio which exists between the periodic times of any two planets is precisely the ratio of the 3/2th power of the mean distances, i.e., of the spheres themselves; provided, however, that the arithmetic mean between both diameters of the elliptic orbit be slightly less than the longer diameter. And so if any one take the period, say, of the Earth, which is one year, and the period of Saturn, which is thirty years, and extract the cube roots of this ratio and then square the ensuing ratio by squaring the cube roots, he will have as his numerical products the most just ratio of the distances of the Earth and Saturn from the sun. 1 For the cube root of 1 is 1, and the square of it is 1; and the cube root of 30 is greater than 3, and therefore the square of it is greater than 9. And Saturn, at its mean distance from the sun, is slightly higher than nine times the mean distance of the Earth from the sun." Kepler Sir Isaac tried to turn this trivial correlation on its head by trying to mesh it with the behavior of experimental sciences and objects at a human level. The followers of Newton haven't a clue nor want to know how he tried to reduce astronomy to the level of experimental sciences but it involves wrecking astronomical insights and methods including how the motions of the planets are resolved by a moving Earth. The under developed adults here don't have the confidence nor the competence to stack up Newton's notions with the approach of the first Sun centered astronomers so they lean on the old familiar 'takemywordforit' convictions they picked up at school from previous generations of followers. People should enjoy what Kepler tried to do before moving on to more meaningful material rather than disappearing down the rabbit hole of theorists. 
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