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Neil DeGrasse Tyson headed down same loony road as Carl Sagan?



 
 
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  #271  
Old October 10th 18, 07:38 AM posted to sci.astro.amateur
Paul Schlyter[_3_]
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Default 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  
Old October 10th 18, 08:16 AM posted to sci.astro.amateur
Quadibloc
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Default Neil DeGrasse Tyson headed down same loony road as Carl Sagan?

On Wednesday, October 10, 2018 at 12:29:38 AM UTC-6, 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  
Old October 10th 18, 08:56 AM posted to sci.astro.amateur
Martin Brown[_3_]
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Default 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/what-i...hertz-thz.html

It is all the rage for non-destructive testing with non-ionising
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  
Old October 10th 18, 02:19 PM posted to sci.astro.amateur
Chris L Peterson
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Default 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  
Old October 10th 18, 02:21 PM posted to sci.astro.amateur
Chris L Peterson
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Default 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  
Old October 10th 18, 04:26 PM posted to sci.astro.amateur
Martin Brown[_3_]
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Default 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  
Old October 10th 18, 05:06 PM posted to sci.astro.amateur
Chris L Peterson
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Posts: 9,850
Default 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  
Old October 10th 18, 05:19 PM posted to sci.astro.amateur
Paul Schlyter[_3_]
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Posts: 1,211
Default 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  
Old October 10th 18, 06:02 PM posted to sci.astro.amateur
Chris L Peterson
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Posts: 9,850
Default 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  
Old October 11th 18, 10:18 AM posted to sci.astro.amateur
Gerald Kelleher
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Default Neil DeGrasse Tyson headed down same loony road as Carl Sagan?

The centrepiece of astrophysics is certainly the so-called '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 'take-my-word-for-it' 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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