YouTube - We Still Don’t Know How Bicycles Work

On 1/29/2021 12:27 PM, Tom Kunich wrote:
On Thursday, January 28, 2021 at 6:03:13 PM UTC-8, AMuzi wrote:
On 1/28/2021 5:54 PM, Frank Krygowski wrote:
On 1/28/2021 4:50 PM, Radey Shouman wrote:
Tom Kunich writes:

On Thursday, January 28, 2021 at 9:08:18 AM UTC-8, AMuzi
wrote:
On 1/28/2021 6:00 AM, Rolf Mantel wrote:
Am 27.01.2021 um 19:19 schrieb Tom Kunich:
On Wednesday, January 27, 2021 at 1:34:38 AM UTC-8, Rolf
Mantel
wrote:
Am 25.01.2021 um 22:44 schrieb Tom Kunich:
On Monday, January 25, 2021 at 10:57:32 AM UTC-8, Frank
Krygowski wrote:

But a warning: Those guys use math.
Why don't you tell us about that math that can measure
the circumference of a oval?
Math does not "measure" but "calculate". Before you can
start
using math, you need a precise description what you mean
by "oval"
(and as soon as you give a precise definition, someboda
can find a
formula for its circumference).

The simplest version of an oval (also called "stadium"
according
to wikipedia) is a circle cut through in the middle
where
the
halves are connected by straight lines, so it is defined
by r =
"Radius of each semi-circle" a = "distance between the
two centers
of the semi-circles"

https://en.wikipedia.org/wiki/Stadium_(geometry)

For this oval, the formula is quite simply 2( pi * r
+ a)

Please do not argue the meanings of words when you know
what is
meant. And do not take a single special case that can be
measured
accurately and pretend that it is fitting for all cases.
Tell us the
perimeter of the orbit of Pluto and then we can see your
accuracies?

Do you understand what is Mathematics and what is not
Mathematics?

The "Orbit of Pluto" is not Mathematics, it's
Astronomy, and
it is not an oval by any definition (Wikipedia claims it's
chaotic due to the 2:3 resonance with Neptune; the
Mathematician and Astronomer Pointcare proved in the
1890's
that the Newtonian interaction of three celestrial bodies
usually leads to "chaos", defining for the first time what
chaos is mathematically).

Only when an Astronomer says "Pluto's orbit can be
approximated by an ellipse with long axis 49 AU and short
axis 30 AU for my purposes", the mathematician can start
calculating the perimeter of that ellipse as a meaningful
approximation for the Astronomer.

Rolf





Basically yes but it's not an ellipse. (a figure with two
foci:
https://www.assignmentpoint.com/wp-c.../Ellipse-1.jpg

)

A planet's orbit can be observed and described. It could
probably be measured but probably not calculated given all
of human knowledge to here as the inputs are myriad (not
only Neptune!) and dynamic.

Argue this with NASA if you like "All orbits are
elliptical, which
means they are an ellipse, similar to an oval. For the
planets, the
orbits are almost circular. The orbits of comets have a
different
shape.

Even if third bodies are ignored entirely, all orbits are not
elliptical. Some are hyperbolic. This happens with
comets that are
traveling relative to the sun at higher than escape
velocity -- they
enter the solar system and then leave, never to return.

I think "orbit" by definition excludes an object with escape
velocity. To orbit means to do it more than once.

But I agree that an object passing by then escaping would
have a hyperbolic trajectory.

They're not exclusive, periodic comets f'instance.

Comets in Earth orbit are always scary because their orbits cannot be calculated with any true accuracy. Every time they pass it could be a collision course. It was the cause of at least one extinction event.

If only the dinosaurs had done better calculations! ;-)

--
- Frank Krygowski

Am 29.01.2021 um 18:20 schrieb Frank Krygowski:
On 1/29/2021 12:01 AM, Radey Shouman wrote:
Frank Krygowski writes:

On 1/28/2021 4:50 PM, Radey Shouman wrote:
Tom Kunich writes:

On Thursday, January 28, 2021 at 9:08:18 AM UTC-8, AMuzi wrote:
On 1/28/2021 6:00 AM, Rolf Mantel wrote:
Am 27.01.2021 um 19:19 schrieb Tom Kunich:
On Wednesday, January 27, 2021 at 1:34:38 AM UTC-8, Rolf
Mantel
wrote:
Am 25.01.2021 um 22:44 schrieb Tom Kunich:
On Monday, January 25, 2021 at 10:57:32 AM UTC-8, Frank
Krygowski wrote:

But a warning: Those guys use math.
Why don't you tell us about that math that can measure
the circumference of a oval?
Math does not "measure" but "calculate". Before you can
start
using math, you need a precise description what you mean
by "oval"
(and as soon as you give a precise definition, someboda
can find a
formula for its circumference).

The simplest version of an oval (also called "stadium"
according
to wikipedia) is a circle cut through in the middle where
the
halves are connected by straight lines, so it is defined
by r =
"Radius of each semi-circle" a = "distance between the
two centers
of the semi-circles"

https://en.wikipedia.org/wiki/Stadium_(geometry)

For this oval, the formula is quite simply 2( pi * r + a)

Please do not argue the meanings of words when you know
what is
meant. And do not take a single special case that can be
measured
accurately and pretend that it is fitting for all cases.
Tell us the
perimeter of the orbit of Pluto and then we can see your
accuracies?

Do you understand what is Mathematics and what is not
Mathematics?

The "Orbit of Pluto" is not Mathematics, it's Astronomy, and
it is not an oval by any definition (Wikipedia claims it's
chaotic due to the 2:3 resonance with Neptune; the
Mathematician and Astronomer Pointcare proved in the 1890's
that the Newtonian interaction of three celestrial bodies
usually leads to "chaos", defining for the first time what
chaos is mathematically).

Only when an Astronomer says "Pluto's orbit can be
approximated by an ellipse with long axis 49 AU and short
axis 30 AU for my purposes", the mathematician can start
calculating the perimeter of that ellipse as a meaningful
approximation for the Astronomer.

Rolf





Basically yes but it's not an ellipse. (a figure with two
foci:
https://www.assignmentpoint.com/wp-c.../Ellipse-1.jpg

)

A planet's orbit can be observed and described. It could
probably be measured but probably not calculated given all
of human knowledge to here as the inputs are myriad (not
only Neptune!) and dynamic.

Argue this with NASA if you like "All orbits are elliptical, which
means they are an ellipse, similar to an oval. For the planets, the
orbits are almost circular. The orbits of comets have a different
shape.

Even if third bodies are ignored entirely, all orbits are not
elliptical.Â* Some are hyperbolic.Â* This happens with comets that are
traveling relative to the sun at higher than escape velocity -- they
enter the solar system and then leave, never to return.

I think "orbit" by definition excludes an object with escape
velocity. To orbit means to do it more than once.

I see many uses of the term "hyperbolic orbit", eg

https://history.nasa.gov/conghand/traject.htm

I'm sure there are plenty of casual uses of the term "orbit," even (as
you showed) by NASA. But ISTM the definition of "orbit" from a reputable
source makes reference to the path being repeated.

For example,
https://www.nasa.gov/audience/forstu...-orbit-58.html

Math talks about orbits quite generically

https://en.wikipedia.org/wiki/Orbit_(dynamics)

For repeated orbits, we use the term "periodic orbit".

Frank Krygowski writes:

On 1/29/2021 12:01 AM, Radey Shouman wrote:
Frank Krygowski writes:

On 1/28/2021 4:50 PM, Radey Shouman wrote:
Tom Kunich writes:

On Thursday, January 28, 2021 at 9:08:18 AM UTC-8, AMuzi wrote:
On 1/28/2021 6:00 AM, Rolf Mantel wrote:
Am 27.01.2021 um 19:19 schrieb Tom Kunich:
On Wednesday, January 27, 2021 at 1:34:38 AM UTC-8, Rolf
Mantel
wrote:
Am 25.01.2021 um 22:44 schrieb Tom Kunich:
On Monday, January 25, 2021 at 10:57:32 AM UTC-8, Frank
Krygowski wrote:

But a warning: Those guys use math.
Why don't you tell us about that math that can measure
the circumference of a oval?
Math does not "measure" but "calculate". Before you can
start
using math, you need a precise description what you mean
by "oval"
(and as soon as you give a precise definition, someboda
can find a
formula for its circumference).

The simplest version of an oval (also called "stadium"
according
to wikipedia) is a circle cut through in the middle where
the
halves are connected by straight lines, so it is defined
by r =
"Radius of each semi-circle" a = "distance between the
two centers
of the semi-circles"

https://en.wikipedia.org/wiki/Stadium_(geometry)

For this oval, the formula is quite simply 2( pi * r + a)

Please do not argue the meanings of words when you know
what is
meant. And do not take a single special case that can be
measured
accurately and pretend that it is fitting for all cases.
Tell us the
perimeter of the orbit of Pluto and then we can see your
accuracies?

Do you understand what is Mathematics and what is not
Mathematics?

The "Orbit of Pluto" is not Mathematics, it's Astronomy, and
it is not an oval by any definition (Wikipedia claims it's
chaotic due to the 2:3 resonance with Neptune; the
Mathematician and Astronomer Pointcare proved in the 1890's
that the Newtonian interaction of three celestrial bodies
usually leads to "chaos", defining for the first time what
chaos is mathematically).

Only when an Astronomer says "Pluto's orbit can be
approximated by an ellipse with long axis 49 AU and short
axis 30 AU for my purposes", the mathematician can start
calculating the perimeter of that ellipse as a meaningful
approximation for the Astronomer.

Rolf





Basically yes but it's not an ellipse. (a figure with two
foci:
https://www.assignmentpoint.com/wp-c.../Ellipse-1.jpg
)

A planet's orbit can be observed and described. It could
probably be measured but probably not calculated given all
of human knowledge to here as the inputs are myriad (not
only Neptune!) and dynamic.

Argue this with NASA if you like "All orbits are elliptical, which
means they are an ellipse, similar to an oval. For the planets, the
orbits are almost circular. The orbits of comets have a different
shape.

Even if third bodies are ignored entirely, all orbits are not
elliptical. Some are hyperbolic. This happens with comets that are
traveling relative to the sun at higher than escape velocity -- they
enter the solar system and then leave, never to return.

I think "orbit" by definition excludes an object with escape
velocity. To orbit means to do it more than once.

I see many uses of the term "hyperbolic orbit", eg

https://history.nasa.gov/conghand/traject.htm

I'm sure there are plenty of casual uses of the term "orbit," even (as
you showed) by NASA. But ISTM the definition of "orbit" from a
reputable source makes reference to the path being repeated.

For example,
https://www.nasa.gov/audience/forstu...-orbit-58.html

I think perhaps they are simplifying for the sake of those in grades 5
to 8. Real orbits, even if elliptic, are generally not exactly
periodic. The elliptic case is a useful idealization based on a
universe containing exactly two point masses.

On Friday, January 29, 2021 at 9:32:17 AM UTC-8, Frank Krygowski wrote:
On 1/29/2021 2:03 AM, Jeff Liebermann wrote:

Please don't tell me that I can't precisely track a planet or orbiting
satellite because it's quite commonly done:
https://www.nlsa.com
More satellite tracking softwa
https://www.google.com/search?q=satellite+tracking+software
I'm not disagreeing with the above. But vaguely related:

For a few years I've been working on a Reflecting Ceiling Sundial.
Something similar to this
https://diallist.files.wordpress.com...-600-x-450.jpg
in which a horizontal bit of mirror bounces a moving dot of sunlight
onto the ceiling. (The curves are analemmas - you can look that up.)

I began by marking the position of the "sundot" on the ceiling at
various times of day. But this is one of the cloudiest areas of the
country, and I've got a huge elm tree overhanging my house, so it's
often difficult to get the data point I want. For a while, I thought I'd
be better off simply computing the coordinates of the sundot, starting
with the precise position of the sun at any date and time.

It turns out it's surprisingly difficult to get a truly precise result
for position of the sun and it's "sundot"! I eventually abandoned the
calculation and went back to simply marking hundreds of points on the
ceiling.
The real problem is that Jeff continues to spout pure bull**** without even bothering to look anything up. We CANNOT calculate orbital motion save with quite course accuracy. The complexity of the orbital motions have been known for thousands of years and no one ever said that we have absolute accuracy over so much as one single solar body.
https://pwg.gsfc.nasa.gov/stargaze/Smotion.htm
Can we calculate to a point where we can get close? Of course. But we can only get close and every solar trip has to be able to modify course. Without a significant atmosphere to modify a landing, the Mars trips landed at unknown places until after they landed and could be pin pointed on the surface of Mars. As I said before, we have had exploratory trips to the moons of Saturn that could not pass close enough for observation because they would use up too much fuel. So when you're talking about solar scales of calculations of an ellipse, those relatively small errors in common math problems add WAY up.

We don't even have an exact position of our own International Space Station and have to continually track it with SATNAV.

There is NO SUCH THING as an exact science. I have spent my entire life making the closest approximation as possible and that is why I was successful.

On Friday, January 29, 2021 at 11:07:15 AM UTC-8, Radey Shouman wrote:
Frank Krygowski writes:

On 1/29/2021 12:01 AM, Radey Shouman wrote:
Frank Krygowski writes:

On 1/28/2021 4:50 PM, Radey Shouman wrote:
Tom Kunich writes:

On Thursday, January 28, 2021 at 9:08:18 AM UTC-8, AMuzi wrote:
On 1/28/2021 6:00 AM, Rolf Mantel wrote:
Am 27.01.2021 um 19:19 schrieb Tom Kunich:
On Wednesday, January 27, 2021 at 1:34:38 AM UTC-8, Rolf
Mantel
wrote:
Am 25.01.2021 um 22:44 schrieb Tom Kunich:
On Monday, January 25, 2021 at 10:57:32 AM UTC-8, Frank
Krygowski wrote:

But a warning: Those guys use math.
Why don't you tell us about that math that can measure
the circumference of a oval?
Math does not "measure" but "calculate". Before you can
start
using math, you need a precise description what you mean
by "oval"
(and as soon as you give a precise definition, someboda
can find a
formula for its circumference).

The simplest version of an oval (also called "stadium"
according
to wikipedia) is a circle cut through in the middle where
the
halves are connected by straight lines, so it is defined
by r =
"Radius of each semi-circle" a = "distance between the
two centers
of the semi-circles"

https://en.wikipedia.org/wiki/Stadium_(geometry)

For this oval, the formula is quite simply 2( pi * r + a)

Please do not argue the meanings of words when you know
what is
meant. And do not take a single special case that can be
measured
accurately and pretend that it is fitting for all cases.
Tell us the
perimeter of the orbit of Pluto and then we can see your
accuracies?

Do you understand what is Mathematics and what is not
Mathematics?

The "Orbit of Pluto" is not Mathematics, it's Astronomy, and
it is not an oval by any definition (Wikipedia claims it's
chaotic due to the 2:3 resonance with Neptune; the
Mathematician and Astronomer Pointcare proved in the 1890's
that the Newtonian interaction of three celestrial bodies
usually leads to "chaos", defining for the first time what
chaos is mathematically).

Only when an Astronomer says "Pluto's orbit can be
approximated by an ellipse with long axis 49 AU and short
axis 30 AU for my purposes", the mathematician can start
calculating the perimeter of that ellipse as a meaningful
approximation for the Astronomer.

Rolf





Basically yes but it's not an ellipse. (a figure with two
foci:
https://www.assignmentpoint.com/wp-c.../Ellipse-1.jpg
)

A planet's orbit can be observed and described. It could
probably be measured but probably not calculated given all
of human knowledge to here as the inputs are myriad (not
only Neptune!) and dynamic.

Argue this with NASA if you like "All orbits are elliptical, which
means they are an ellipse, similar to an oval. For the planets, the
orbits are almost circular. The orbits of comets have a different
shape.

Even if third bodies are ignored entirely, all orbits are not
elliptical. Some are hyperbolic. This happens with comets that are
traveling relative to the sun at higher than escape velocity -- they
enter the solar system and then leave, never to return.

I think "orbit" by definition excludes an object with escape
velocity. To orbit means to do it more than once.

I see many uses of the term "hyperbolic orbit", eg

https://history.nasa.gov/conghand/traject.htm

I'm sure there are plenty of casual uses of the term "orbit," even (as
you showed) by NASA. But ISTM the definition of "orbit" from a
reputable source makes reference to the path being repeated.

For example,
https://www.nasa.gov/audience/forstu...-orbit-58.html
I think perhaps they are simplifying for the sake of those in grades 5
to 8. Real orbits, even if elliptic, are generally not exactly
periodic. The elliptic case is a useful idealization based on a
universe containing exactly two point masses.
The rather massive difference between a mathematical problem and the real world.

Tom Kunich writes:

On Friday, January 29, 2021 at 11:07:15 AM UTC-8, Radey Shouman wrote:
Frank Krygowski writes:

On 1/29/2021 12:01 AM, Radey Shouman wrote:
Frank Krygowski writes:

On 1/28/2021 4:50 PM, Radey Shouman wrote:
Tom Kunich writes:

On Thursday, January 28, 2021 at 9:08:18 AM UTC-8, AMuzi wrote:
On 1/28/2021 6:00 AM, Rolf Mantel wrote:
Am 27.01.2021 um 19:19 schrieb Tom Kunich:
On Wednesday, January 27, 2021 at 1:34:38 AM UTC-8, Rolf
Mantel
wrote:
Am 25.01.2021 um 22:44 schrieb Tom Kunich:
On Monday, January 25, 2021 at 10:57:32 AM UTC-8, Frank
Krygowski wrote:

But a warning: Those guys use math.
Why don't you tell us about that math that can measure
the circumference of a oval?
Math does not "measure" but "calculate". Before you can
start
using math, you need a precise description what you mean
by "oval"
(and as soon as you give a precise definition, someboda
can find a
formula for its circumference).

The simplest version of an oval (also called "stadium"
according
to wikipedia) is a circle cut through in the middle where
the
halves are connected by straight lines, so it is defined
by r =
"Radius of each semi-circle" a = "distance between the
two centers
of the semi-circles"

https://en.wikipedia.org/wiki/Stadium_(geometry)

For this oval, the formula is quite simply 2( pi * r + a)

Please do not argue the meanings of words when you know
what is
meant. And do not take a single special case that can be
measured
accurately and pretend that it is fitting for all cases.
Tell us the
perimeter of the orbit of Pluto and then we can see your
accuracies?

Do you understand what is Mathematics and what is not
Mathematics?

The "Orbit of Pluto" is not Mathematics, it's Astronomy, and
it is not an oval by any definition (Wikipedia claims it's
chaotic due to the 2:3 resonance with Neptune; the
Mathematician and Astronomer Pointcare proved in the 1890's
that the Newtonian interaction of three celestrial bodies
usually leads to "chaos", defining for the first time what
chaos is mathematically).

Only when an Astronomer says "Pluto's orbit can be
approximated by an ellipse with long axis 49 AU and short
axis 30 AU for my purposes", the mathematician can start
calculating the perimeter of that ellipse as a meaningful
approximation for the Astronomer.

Rolf





Basically yes but it's not an ellipse. (a figure with two
foci:
https://www.assignmentpoint.com/wp-c.../Ellipse-1.jpg
)

A planet's orbit can be observed and described. It could
probably be measured but probably not calculated given all
of human knowledge to here as the inputs are myriad (not
only Neptune!) and dynamic.

Argue this with NASA if you like "All orbits are elliptical, which
means they are an ellipse, similar to an oval. For the planets, the
orbits are almost circular. The orbits of comets have a different
shape.

Even if third bodies are ignored entirely, all orbits are not
elliptical. Some are hyperbolic. This happens with comets that are
traveling relative to the sun at higher than escape velocity -- they
enter the solar system and then leave, never to return.

I think "orbit" by definition excludes an object with escape
velocity. To orbit means to do it more than once.

I see many uses of the term "hyperbolic orbit", eg

https://history.nasa.gov/conghand/traject.htm

I'm sure there are plenty of casual uses of the term "orbit," even (as
you showed) by NASA. But ISTM the definition of "orbit" from a
reputable source makes reference to the path being repeated.

For example,
https://www.nasa.gov/audience/forstu...-orbit-58.html
I think perhaps they are simplifying for the sake of those in grades 5
to 8. Real orbits, even if elliptic, are generally not exactly
periodic. The elliptic case is a useful idealization based on a
universe containing exactly two point masses.
The rather massive difference between a mathematical problem and the real world.

Really the differences may be too small to measure, at least in orbital
mechanics.

On Fri, 29 Jan 2021 09:27:25 -0800, Tom Kunich scribed:

On Thursday, January 28, 2021 at 6:03:13 PM UTC-8, AMuzi wrote:

They're not exclusive, periodic comets f'instance.

Comets in Earth orbit are always scary because their orbits cannot be
calculated with any true accuracy. Every time they pass it could be a
collision course. It was the cause of at least one extinction event.

NO, it was a major factor in the end of the age of reptiles in that it
hastened already changing conditions on earth. I believe, of the five
major life extinction events, two had planetary body impact as as major
factor. Of course this may all be modern propaganda by acolytes of the
fungal overlords who claim to be the repeated source of 'life' on earth.