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Messages - BillO

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401
Poliastro says that the image represents numerical methods for the Restricted Three Body Problem. Are you to assert that you know better than an astrodynamics software developer?
No, I certainly would not do that.  However, I can't see the whole thing here.  I have no idea of the work he is talking about and what the goals were.  Do you have a link handy to the original work?

402
Regarding the Pop-Science Magazine Solar System Sim written in Applesoft BASIC
Pop-Science?  Maybe, but I never had a subscription to them.  Just the ones I mentioned.

Quote
I took a look at this one. It appears to merely be creating 2-body orbits around a static sun. It does not appear to be a three-body or n-body problem simulator.
Bang, there it goes.  Either you are being intentionally intellectually dishonest or you don't know how to read this code.  Maybe get someone else to have a look at it if you have trouble with simple linearized math.  Look at the subroutine beginning at 440 and returning at 590.  You can see how every object entered into the system is taken into account and the force between each is calculated using Newton's law of Universal gravity.  Every single one.  I get the feeling that you think none of your FE followers will be able or inclined to read the code or do the simple math so that you can say whatever you wish.

Quote
I placed the code from the last page into an online Applesoft BASIC Emulator here: http://www.calormen.com/jsbasic/

Using the settings Bill gave, I made two Earths, rotating in opposite directions, in the same orbit.
Why?  Why did you not do the 4 body situation?

Quote
Here were the results:
Okay, so that's exactly what I would expect.    How long did you let it run?.  I wrote no collision routine, so bodies will just pass right through each other when in precisely the same orbit. They are basically dimensionless.  This situation may not create an instability for quite a while, if ever.  If you want to do that put one 'earth' on a slightly different orbit - for instance use the average distance and the average speed.  That way the small offset of gravitation will create an instability.  It should begin to visibly blow up in about 4 or 5 orbits.

Try this:
Code: [Select]
Sun-Earth1-Earth2 (3 Objects)

Sun
M1 = 1.9885E30
X1 = 0
Y1 = 0
VX1 = 0
VY1 = 0

Earth 1
M2 = 5.9724E24
X2 = 1.5210E11
Y2 = 0
VX2 = 0
VY2 = 29290

Earth 2
M3 = 5.9724E24
X3 = -1.496E11
Y3 = 0
VX3 = 0
VY3 = 29780

Scale = 2E11
Time Step = 50000

403
Flat Earth Investigations / Re: Water on Mars
« on: July 26, 2018, 02:57:04 PM »
Perhaps these organizations should be more interested in correcting the current course of our own world instead of fixating on other lifeless rocks just to satiate their curiosity.
There is something to be said for that for sure.

However, if humans did not try to satiate their curiosity we'd still be in the stone age.  So there is something to be said for that too. 

404
All it uses is Newton's law of universal gravitation.  When I saw this thread I remembered it but was sure it had been lost forever, however yesterday I found a few old floppy disks and sure enough my program was there and readable.  Now, this is a dreadfully simple program with no fancy GR or corrections for coarse step-wise calculation approximations, and is further limited by the dismal Applesoft floating point precision yet it will faithfully run a simulation of the Sun, Mercury, Venus and Earth for the equivalent of hundreds of years - without the orbits getting chaotic and looking like knots...
So, it is totally useless and crapola, uh..?
This is really not worth replying to ... but  I never said it was going to be anything but a demonstration that purely numerical methods can produce stable systems of multiple bodies.  It does.  q.e.d.

needless and mindless words snipped for brevity becasue this does not even have a moving sun included and actually demonstrates ZERO use of Newton's formulas.
Ahhh, that's odd as there at least 2 of them in there.  My guess is you don't have much in the way of math or computer skills.  A bit of blustering then?  Would you care to demonstrate how the sun's motion would be significant to the orbital dynamics of the solar system?


Yep, absolute and verifiable blustering...

405
Incorrect

These are numerical solutions. The Runge-Kutta method is demonstrated in the second image. The Rung-Kutta method is a numerical method.

https://en.wikipedia.org/wiki/Runge%E2%80%93Kutta_methods

Quote
In numerical analysis, the Runge–Kutta methods are a family of implicit and explicit iterative methods, which include the well-known routine called the Euler Method, used in temporal discretization for the approximate solutions of ordinary differential equations

https://www.intmath.com/differential-equations/12-runge-kutta-rk4-des.php

Quote
Runge-Kutta is a common method for solving differential equations numerically. It's used by computer algebra systems.
Yeah, I know the Runge-Kutta methods and what they are for - you apparently don't.

Going back to the:http://www.scholarpedia.org/article/Three_body_problem#Equations  the entire preamble is using mathematical analysis to derive the Hamiltonians which they then use to create a system of differential equations which then need to be integrated - in their case by computer.

You do know what is meant by mathematical analysis, don't you?  Calculus is one of the main processes of mathematical analysis.  If a solution is arrived by trough doing calculus (especial integration) it is an analytic solution, whether or not that integration was done by a machine or not.  Your references are attempting to compute an analytic solution.  Whether or not they use Runge-Kutta methids or not to do the integration.

Quote
I seriously doubt that your magazine-provided solar system sim does what you think it does. I will have a look when I get a chance.
Well, this should be interesting and a test of you intellectual honesty.

Yes the magazine provided the algorithm, but it is simple to understand and I really don't need you to 'splain it to me.  For each object defined: use Newton's law of universal gravitation to determine the net force on it due to each of the other other bodies.  Use Newtons 2nd law of motion to calculate the change in velocity.  Move the object one step.  Repeat.


406

http://www.scholarpedia.org/article/Three_body_problem

https://wiki.tfes.org/Celestial_Mechanics_Cannot_Predict_The_Solar_System#The_Best_of_the_Best

Do these look like Heliocentric Orbits to you?
Neither of these are attempts at numerical solutions/simulations.  They are both the result of trying to find an analytic solution and run the solution on a computer to test it.  The two approaches use computers but are entirely different.  There is no analytic solution (yet), but numerical solutions exist and are deadly accurate.  You've been told this by many people in this thread.  You're mixing things up because you don't understand what your dealing with.

My butt simple numerical solution is there for you or anyone else to try.  I'll give you all the help you need to get it going and to understand it.

407
You solved all of the the n-body problems? Amazing. Why not release your wonder to the world?
Typical FE'er exaggeration.  Where exactly did I say I solved all of the n-body problems?

Here is the Applesoft Basic code
Code: [Select]
20  INPUT "ENTER NUMBER OF OBJECTS";N
 30  DIM M(10),A(10,2),S(10,2),V(10,2),LP(10),LQ(10)
 50 G = 6.67E - 11
 60  FOR I = 1 TO N
 70  PRINT : PRINT "FOR OBJECT ";I;", ENTER:"
 90  INPUT "MASS : ";M(I)
 110  INPUT "X    : ";S(I,1)
 130  INPUT "Y    : ";S(I,2)
 150  INPUT "VX   : ";V(I,1)
 170  INPUT "VY   : ";V(I,2)
 180  NEXT I
 190  PRINT
 200  INPUT "SCALE FACTOR FOR X ";SX
 210 SY = SX * .85
 220  INPUT "TIME STEP DURATION ";DT
 240  HGR : POKE  - 16302,0
 250  GOSUB 440
 260  FOR I = 1 TO N
 270 V(I,1) = V(I,1) - .5 * A(I,1) * DT
 280 V(I,2) = V(I,2) - .5 * A(I,2) * DT
 290  NEXT I
 300  FOR I = 1 TO N
 310 CX = .5 * A(I,1) * DT
 320 CY = .5 * A(I,2) * DT
 330 VX = V(I,1) + CX
 340 VY = V(I,2) + CY
 350 S(I,1) = (CX + VX) * DT + S(I,1)
 360 S(I,2) = (CY + VY) * DT + S(I,2)
 370 V(I,1) = VX + CX
 380 V(I,2) = VY + CY
 390  NEXT I
 410  GOSUB 600
 420  GOSUB 440
 430  GOTO 300
 440  FOR I = 1 TO N
 450 A(I,1) = 0:A(I,2) = 0
 470  NEXT I
 480  FOR I = 1 TO N - 1
 490  FOR J = I + 1 TO N
 500 RD = ((S(I,1) - S(J,1)) ^ 2 + (S(I,2) - S(J,2)) ^ 2) ^ 1.5
 510 A1 = G * M(J) * ((S(J,1) - S(I,1)) / RD)
 520 A2 = G * M(J) * (S(J,2) - S(I,2)) / RD
 530 A(I,1) = A(I,1) + A1
 540 A(I,2) = A(I,2) + A2
 550 A(J,1) = A(J,1) - A1 * M(I) / M(J)
 560 A(J,2) = A(J,2) - A2 * M(I) / M(J)
 570  NEXT J
 580  NEXT I
 590  RETURN
 600  FOR I = 1 TO N
 610  IF  ABS (S(I,1)) > SX THEN 690
 620  IF  ABS (S(I,2)) > SY THEN 690
 630 P = 139 +  INT (.5 + 140 * S(I,1) / SX)
 640 Q = 95 +  INT (.5 + 96 * S(I,2) / SY)
 650  HCOLOR= 3: HPLOT P,Q
 660  IF P = LP(I) AND Q = LQ(I) THEN 690
 670  HCOLOR= 0: HPLOT LP(I),LQ(I)
 680 LP(I) = P:LQ(I) = Q
 690  NEXT I
 700  RETURN

Enter masses in kilograms (kg)
Distances in meters (m)
Velocities in meters per second (m/s)


The scale factor should be somewhat greater than the  radius of the largest orbit.
The time step duration is a balance between accuracy and speed the lower the number the more accurate, but the slower the simulation will run.  See the examples and play around with it.

When you enter a body, you need to enter the correct speed that goes with the distance you choose.  I usually enter perihelion and the minimum orbital speed.  Don't try to enter the average distance and average speed as those measurements usually do not align.  For simplicity sake I always line up the bodies along the center axis (Y=0)

Here are two simulations.  The first is the Earth and moon 2 body system, the 2nd is the Sun, Mercury, Venus and Earth 4 body system.
Code: [Select]
Earth-Moon (2 Objects)

Earth
M1 = 5.9723E24
X1 = 0
Y1 = 0
VX1 = 0
VY1 = -10

Moon
M2 = 7.346E22
X2 = 4.055E8
Y2 = 0
VX1 = 0
VY2 = 970

Scale = 1E9
Time Step = 50000


Sun-Mercury-Venus-Earth (4 Objects)

Sun
M1 = 1.9885E30
X1 = 0
Y1 = 0
VX1 = 0
VY1 = 0

Mercury
M2 = 3.3011E23
X2 = 6.983E10
Y2 = 0
VX = 0
VY = 38860

Venus
M3 = 4.8675E24
X3 = -1.0894E11
Y3 = 0
VX3 = 0
VY3 = -34790

Earth
M4 = 5.9724E24
X3 = 1.5210E11
Y3 = 0
VX3 = 0
VY3 = 29290

Scale = 2E11
Time Step = 50000

I've run the 4 body example for 10 hours.  That's 2110 years of time simulated.  I'm going to set it to run overnight.

AS I said, the will run unaltered on a real Apple II with Applesotf Basic, o ron the AppleWIN emulator.   However, feel free to port to something else if you wish.

408
Tom is so utterly worng on this, and it can easily be proven.

Back in 1980 when I had just wrapped up community college and got my fist job I rewarded myself with an Apple II+.  One of the fist things I did on that machine was write a celestial mechanics simulation based on an article in Popular Electronics, Byte or Scientific American (back when it was a decent magazine).  All it uses is Newton's law of universal gravitation.  When I saw this thread I remembered it but was sure it had been lost forever, however yesterday I found a few old floppy disks and sure enough my program was there and readable.  Now, this is a dreadfully simple program with no fancy GR or corrections for coarse step-wise calculation approximations, and is further limited by the dismal Applesoft floating point precision yet it will faithfully run a simulation of the Sun, Mercury, Venus and Earth for the equivalent of hundreds of years - without the orbits getting chaotic and looking like knots.  It can handle more than 4 bodies too, but that is stressing it's abilities.  Tom would have us believe that folks with access to the worlds fastest and most precise computers - people with PhDs and in astrophysics and years of experience with numerical methods can't get it to work.  I have no idea where Tom digs this BS up from.

I've been running the program on both real hardware (I have an old Apple //e) and on the AppleWin emulator under Windoze 10 for hours now and no issues whatsoever.  The instance running on the emulator simulates about 211 years per hour (~17 seconds for earth's orbit).  If anyone is interested I will post the code and a couple of samples as well as an explanation on how to run it.  It's pretty simple.  Perhaps someone could port it to C or Python to run natively on a PC so that we can even get more speed and precision.

Just let me know.

409
Flat Earth Theory / Re: Detailed flight times and distances
« on: July 24, 2018, 11:35:25 PM »
No, that's fine.  Thx.

410
Flat Earth Theory / Re: Query: Age and formation of the Flat Earth
« on: July 24, 2018, 11:32:40 PM »
Mot more than you would expect.  That first image is the entire frame from the NAC. the 2d is a unmagnified crop from the same camera.

Below is a 5x magnification of just the object.  Not really all that great.

411
Flat Earth Theory / Re: Detailed flight times and distances
« on: July 24, 2018, 06:31:50 PM »
If you want to know the distance between 2 points on the 2D map you have to zoom in some. The way you are doing it is incorrect.
I tried to look this method up and could find nothing.  Would you be able to provide a link or possibly demonstrate?

412
Flat Earth Theory / Re: Query: Age and formation of the Flat Earth
« on: July 24, 2018, 06:30:03 PM »
None of the current theory on how bodies form in space will allow for a flat body. 

Depending on what you believe about the creation of celestial bodies this is incorrect.

-God can create a flat disk in space in less than one nanosecond.
-God can create a flat disk in space in billions of years.
I'm atheist.

Quote
-I see the flat disk rings of Saturn. isn't there some theory about that?
Other planets have rings too, but none of them are single objects.  They are made up of billions of tiny objects.

Here is a Cassini photo of a larger object forming slowly in Saturn's rings.  You can see how the material first accretes to a disc, then begins to collapse into the nearly spherical body of the object.


Another angle:

413
Flat Earth Investigations / Re: The Lunar Module
« on: July 24, 2018, 06:18:28 PM »
No matter what we may believe about the shape of the earth, we can all agree that NASA's SLS program is fake.
We know that it costs $400 million to develop a rocket (that can launch and land).  What has NASA done with the other 11.5 BILLION?
Probably wasted it.  They are a government organization after all.  Do you seriously expected them to be efficient?

Also, you seem to be ignoring the mission capabilities they are designing the SLS for.  They go well beyond the interesting but much more limited SpaceX  Falcon 9.

414
Flat Earth Investigations / Re: The Lunar Module
« on: July 24, 2018, 05:59:26 PM »
You really don't expect this lunar hoax to be believed when NASA itself admits it's impossible. I;m not sure what you hope to gain from idiots who have been indoctrinated to a spinning globe? Aren't they all broke now anyway?



It doesn't surprise me you’d drag something like this up.  NASA admit no such thing.  The twit that created the video takes a lot out of context and is not telling you all the facts.  Lying by omission – over and over again.

Here are some pertinent facts he left out.

The trajectory of the moon missions avoided the inner belt completely and just barely skimmed the outer layers of the outer belts.  The radiation in the outer belts is mostly only high energy electrons which would be mostly shielded for by the outer hull (thin aluminum is all that is required).  All that said, they were through the outer belts in about an hour.
Total radiation dose experienced by the astronauts on the lunar flights, most of it experienced in the space between earth and the moon, was under 1.2 rads.  Less than half one quarter of the dose deemed to be the onset of harm.

For many of the planned and potential Orion missions, they do not have the luxury of a voiding the Van Allen belts due to the required flight profiles.  So they do need to beef up the shielding.

The remaining Saturn 5 launch vehicle components were destroyed.  So, yeah, until the Orion equipment is built we no longer have the ability to launch humans beyond a few hundreds of miles.

While the temperature does rise on average in the atmosphere as you ascend through the thermosphere the air is so rarefied that there is practically no heat energy there.  The density of molecules is so low in the thermosphere that the mean free path of a molecule (the average distance it must travel before colliding with another molecule) is about 1 km. Will aluminum melt there?  Not a chance in hell.  Since there is so little energy to be transferred to the metal, it will be radiated away before it has a chance to even warm up.

Watching, and believing, the utter nonsense in videos like this is going to damage your brain.  Like you FE’ers always say, do your own research and avoid getting your knowledge from the sewer that is YouTube.

415
Flat Earth Theory / Re: Query: Age and formation of the Flat Earth
« on: July 24, 2018, 04:16:36 PM »
I have searched this site and cannot find anything about how and when the Flat Earth was formed.

Is there any accepted estimate on when it formed and how that formation occurred?

Two people are looking at a shape. One person says it's a relatively flat 2d circle and another person says it's a more round 3d sphere shape.

Then you come along and ask how old the shape is and how it was created.  Well these are very loaded questions and the answers would range from

Age: less than 10,000 years. How it was formed: God.
to
Age: Billions of years. How it was formed: Unknown but the big bang theory seems promising.

This variation about the origins and age of the universe are independent of theory about the shape of the earth.
None of the current theory on how bodies form in space will allow for a flat body.  So that part of my question was seeking, though inquiry, what new and wonderful theory the FEs had devised to account for what caused it.  The other, on the age, was to determine how fast this enormous flat body they thought up might be now traveling WRT it's birthplace.  I was then going to do a follow-up question on what their zetetic  efforts had come up with regarding the cause of the acceleration itself.  It is apparent, however, that hundreds of years of flat-earth thinking on these matters has not even begun to scratch the surface on some of these questions.  Maybe they tried and failed, maybe they did not like the implications such thought processes offered.  Maybe they are just not inquisitive enough to even try.  Who knows?  No one is talking.

They know the earth is flat, they just don't have a clue how that happened.

416
The speed of light is variable: it varies with the density of various layers of aether/ether.
Okay, your belief in an aether/ether puts your entire discourse into deep doubt.

There is no evidence for an aether.  There is no test for an aether.  There is no way to observe and aether.

If it walks like nothing, quacks like nothing and smells like nothing - it's nothing.

Next thing is you'll be believing in a flat earth.  ::)

417
Flat Earth Investigations / Re: Dome or CGI?
« on: July 23, 2018, 06:05:47 PM »
First, the effect of bending light is pretty small.  Light has to pass pretty close to some enormously massive object to see the kind of light bending you are depicting.

Second, the universe is a pretty empty place all in all.  With the average distance between stars in our neck of the woods being something like 8 light years there are ample gaps for light to make it through unbent.  The average distance between neutron stars and black holes, those things that will bend light significantly, is measured in the many 100s if not 1000s  of light years.

418
Flat Earth Theory / Re: Is Google maps accurate?
« on: July 23, 2018, 01:19:57 PM »
The distances in the video are based on the Latitude/Longitude coordinate system, which is a spherical coordinate system. Of course you will get a sphere.
Brilliant.

Then provide us with a coordinate system that will lead us to conclude it's a flat earth, and that still does not mangle the distances between known places on that flat earth, please.

419
Flat Earth Theory / Re: Query: Age and formation of the Flat Earth
« on: July 22, 2018, 10:28:10 PM »
Why are you expecting a complete model of nature?
I come from a scientific background.  I seek to explain things.  I am inquisitive and seek knowledge and understanding for the pure joy of it.

The effort to provide a complete model of nature beyond all else was the main issue which plauged  the history of science. Read Zetetic and Theoretic Defined and Compared.
The end of the very fist sentence at that page you linked to gives you the answer.  "THE term Zetetic is derived from the Greek verb Zeteo; which means to search, or examine; to proceed only by inquiry; to take nothing for granted, but to trace phenomena to their immediate and demonstrable causes. "

However, FE followers claim to be zetetic, but they do not seem very good at it.  So much about the concept of a flat earth leaves so many phenomena without finding the cause.  Would you like a list?
  • What causes the sun to light up and provide heat?
  • What causes the sun to speed around at over 1000 miles an hour?
  • What causes the sun to stay circling the plain beneath, rather than just flying off in a straight line?
  • What causes the sun to change course over a year
  • What causes the sun to stay at its altitude
  • If the flat earth hypotheses has any validity, what causes it to incorrectly predict the sun's observed angle at sunrise and sunset?

They are only a few of the things concerning just the sun that your zetetic searching has yet to demonstrate a cause for, immediate or otherwise.

You do realize that scientists do not use the meaning of 'Theory' as defined at that page, don't you?  The definition there better describes what scientists call an hypothesis.  Scientists do not call a thing a 'theory' unless it has been demonstrated over an over again and found to accurately describe nature in some useful way.

420
Newton couldn't figure out how to make his system work. The greatest mathematicians couldn't figure out how to make it work. Supercomputers could not provide the solution. The problems are insoluble. The heliocentric systems of Copernicus, Newton, and Kepler do not work. The current state of affairs is that it doesn't work at all. It is a fantasy.
Is your issue with the model, or with the idea that things can orbit at all?

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