Page 3 of 6 FirstFirst 12345 ... LastLast
Results 61 to 90 of 172

Thread: Trojan

  1. #61
    Join Date
    Sep 2015
    Posts
    302
    Quote Originally Posted by grant hutchison View Post
    I see surprisingly well-ordered movement, with stars in close proximity moving in approximately the same direction. We wouldn't see a spiral structure if the movement were as chaotic as you suggest.
    I'd say extremely small, by virtue of the parallel streaming I'm seeing. You know that animation isn't to scale, don't you?
    It's up to you to offer some support for your estimates.
    Grant Hutchison
    Don't you see that many stars are actually crossing the path of other stars?

  2. #62
    Join Date
    Aug 2008
    Location
    Wellington, New Zealand
    Posts
    3,581
    Quote Originally Posted by Dave Lee View Post
    Spiral galaxy is not a simple orbital system as the Solar system. ...
    Which is exactly why there are no signs of Trojan stars in a spiral galaxy!
    A spiral galaxy is not a central mass (as in the Sun) with smaller masses orbiting it (as in the planets) forming Lagrangian points where even smaller masses can orbit the central mass.
    Last edited by Reality Check; 2018-Jan-07 at 09:15 PM.

  3. #63
    Join Date
    Aug 2008
    Location
    Wellington, New Zealand
    Posts
    3,581
    Quote Originally Posted by Dave Lee View Post
    ...If you understand how "Trojan point" works in spiral galaxy - you have solved the spiral galaxy structure enigma
    We do understand - there is no such thing. Thus imaginary "Trojan point(s)" cannot explain the already explained spiral galaxy structure ("Since the 1960s, there have been two leading hypotheses or models for the spiral structures of galaxies").

  4. #64
    Join Date
    Jun 2007
    Posts
    5,512
    Quote Originally Posted by Dave Lee View Post
    Don't you see that many stars are actually crossing the path of other stars?
    So what if they are? To collide, they would have to approach within the combined stellar radii of each other, when they generally don't approach within millions of times that distance. Why would they collide with any great frequency? How does density wave theory have anything to do with the collision rate? And what would orbiting a Trojan point possibly have to do with preventing collisions?

  5. #65
    Join Date
    Aug 2008
    Location
    Wellington, New Zealand
    Posts
    3,581
    Quote Originally Posted by Dave Lee View Post
    So the main question should be:
    How can we explain the structure of spiral galaxy by using "Trojan point"?...
    The previous posts have already given the answer - we cannot.
    1. There is no "Trojan point" - it is the Lagrangian points 4 and 5 that may contain Trojan objects.
    The reason that these can be occupied in the Solar System is because it is essentially full of with objects whizzing around to occupy the points. But stars in galaxies are light years apart and rarely get close.
    2. Locality is not "relativity" (special or general!).
    3. A "might" is not good enough - you need to produce evidence that starts in the galaxy have Lagrangian points 4 and 5.
    4. A "branches in a tree" unsupported assertion is a fantasy until you produce evidence.

    A list of questions that you need to answer is not an ATM idea.

    A "Trojan camp" unsupported assertion needs evidence. Followed by posts with more "Trojan" word salad rather than an explanation or evidence. And irrelevance of the standard mainstream explanation of why the Sun bobs through the galactic disk periodically with an unsupported dismissal. The force of gravity from a spherical mass (quoted later however the galaxy disk is not a sphere) being an inverse square law does not show that any object rising in the gravitational field will escape from the spherical mass. If that object does not exceed the escape velocity it will fall back to the spherical mass. Now replace that inverse square law with the appropriate law for a massive disk and a similar situation occurs. The Sun has a velocity less than the escape velocity of the Milky Way. The Sun "rises" above the disk, is pulled back down, passes through the disk to "fall" downward and then is pulled back up.
    Last edited by Reality Check; 2018-Jan-07 at 10:02 PM.

  6. #66
    Join Date
    Aug 2008
    Location
    Wellington, New Zealand
    Posts
    3,581
    Quote Originally Posted by Dave Lee View Post
    ...Therefore, isn't moving randomly up and down.
    You did not read what you cited carefully enough. A periodic motion is not random. It is vey like "some kind of a ball which it thrown upwards and then goes down wards".
    Repeating a "Trojan" fantasy does not make an ATM idea - you need evidence.
    Density wave theory is Newton's laws applied to a galaxy, especially "gravitational attraction between stars at different radii". So your "random motion" assertion is false.
    Density wave theory is also applied to Saturn's rings - again with none of your "random" assertion.

  7. #67
    Join Date
    Oct 2009
    Location
    a long way away
    Posts
    10,034
    Quote Originally Posted by Dave Lee View Post
    Based on that Density_wave_theory what is the chance for collisions between the stars?
    Is it 1%, 10% or 50%?
    It is up to you to tell us. You could start by looking at the average distance between stars, the size of stars and estimating the probability of a collision.

    How many collisions does this predict? How does that compare with the number we observe?

  8. #68
    Join Date
    Jul 2005
    Posts
    15,048
    Quote Originally Posted by Dave Lee View Post
    Sure!
    But it orbits up and down.
    Excellent. Direct question: Do you agree that at some point it has to stop going up and start coming down?

    Grant Hutchison

  9. #69
    Join Date
    Jul 2005
    Posts
    15,048
    Quote Originally Posted by Dave Lee View Post
    Don't you see that many stars are actually crossing the path of other stars?
    No, you're being fooled by an optical illusion. The stars are moving in roughly circular, roughly parallel tracks, and are transiently resident in the spiral arms before moving out the other side. Because the transient structure of the arms is moving more slowly than the stars themselves, it gives the impression that stars are joining the arms and then spiralling inwards, across the trajectories of other stars. But that's not what's happening, and it's not how density waves work.
    It's a potent illusion, but it's the sort of problem you run into if you try to reason from Wikipedia animations.

    Grant Hutchison

  10. #70
    Join Date
    Jun 2005
    Posts
    12,554
    Quote Originally Posted by Dave Lee View Post
    Easy!
    If you throw something upwards, it comes down again.
    BUT, it must reduce its velocity, stop and then come back.
    If the Sun stop and come back than I fully accept your explanation.
    However, based on my understanding, the Sun never reduces its velocity.
    Then by your theory, a home run would never come down, because it never stops. Then why does a baseball come back down even though the batter hits it upwards?
    As above, so below

  11. #71
    Join Date
    Oct 2009
    Location
    a long way away
    Posts
    10,034
    Quote Originally Posted by Dave Lee View Post
    However, based on my understanding, the Sun never reduces its velocity.
    Then your understanding is wrong.

    Maybe you don't understand about vectors? And the fact that the Sun can have a constant velocity in one direction but a varying velocity in another direction. It is that vertical component that stops and reverses.

  12. #72
    Join Date
    Sep 2015
    Posts
    302
    Quote Originally Posted by Strange View Post
    Maybe you don't understand about vectors? And the fact that the Sun can have a constant velocity in one direction but a varying velocity in another direction. It is that vertical component that stops and reverses.
    Any orbital cycle set a sinusoidal wave.

    Please look at the following:

    https://www.quora.com/What-are-sinusoidal-waves

    "If you mark one point on a circle and then rotate that circle at a fixed speed you will notice the point going up and down."

    Let's assume that we start our measurements when the Sun is located at 0 Degree (Galactic plane).
    The Sun orbits around its Trojan Point.
    As it gets to the 90 Degree, the Sine wave will be in its maximal pick.
    When it moves of 270 Degree, The sine wave will be in its minimal value.
    At 0 and 180 degree, the Sun should cross the galactic plane.
    As you can see, the sun orbits in a constant speed, while it goes up and down.
    I'm not speaking about the horizontal or the vertical vectors of the sine wave.
    I 'm speaking about the fixed orbital speed of the Sun.
    Is it clear to you?
    Do you still believe that I do not understand in vectors?
    Last edited by Dave Lee; 2018-Jan-08 at 12:05 PM.

  13. #73
    Join Date
    Jun 2005
    Posts
    12,554
    Iím repeating myself, but when you throw a ball like a tennis ball toward another person, it will stop rising and start falling without ever stopping. How do you explain that?
    As above, so below

  14. #74
    Join Date
    Sep 2015
    Posts
    302
    Quote Originally Posted by Jens View Post
    I’m repeating myself, but when you throw a ball like a tennis ball toward another person, it will stop rising and start falling without ever stopping. How do you explain that?
    You have to understand how gravity really works.
    So, let me explain:

    There are only two steady states cases for gravity.

    1. Orbital motion - In this case, if there are two objects, they both orbit around their center of mass.
    This motion should be stable for quite long time. Technically, without external interruption, they should keep this movement for long time.
    We know all the relevant mathematical calculation for that.
    2. Direct contact - In this case there is a direct contact between the objects. For example - if you throw a ball like a tennis ball toward another person, it will come down and set a direct contact with the other person or with the ground. It won't move again without setting an external power.


    There is no other stable case for gravity
    Last edited by Dave Lee; 2018-Jan-08 at 12:47 PM.

  15. #75
    Join Date
    Sep 2015
    Posts
    302
    There is no free lunch in the galaxy.
    If you wish to stay in the galaxy, you have only two options:

    1. Orbit around other object (or Torjan point) and follow its movement in the galaxy.
    2. Set a direct contact with other object and stay with him.

    If you are a star, and you have a Headache from orbiting, you have two options:

    1. set a direct contact with other star and follow with him its orbital path.
    2. Or you would be kicked out from the arm and from the galaxy.

    There is no other way to stay in our galaxy

    Please remember - if you move out from the Arm, you would never ever come back again. Please hold the arm. There is no second chance!
    Last edited by Dave Lee; 2018-Jan-08 at 01:00 PM.

  16. #76
    Join Date
    Jul 2005
    Posts
    15,048
    Quote Originally Posted by Dave Lee View Post
    Any orbital cycle set a sinusoidal wave.

    Please look at the following:

    https://www.quora.com/What-are-sinusoidal-waves

    "If you mark one point on a circle and then rotate that circle at a fixed speed you will notice the point going up and down."

    Let's assume that we start our measurements when the Sun is located at 0 Degree (Galactic plane).
    The Sun orbits around its Trojan Point.
    As it gets to the 90 Degree, the Sine wave will be in its maximal pick.
    When it moves of 270 Degree, The sine wave will be in its minimal value.
    At 0 and 180 degree, the Sun should cross the galactic plane.
    As you can see, the sun orbits in a constant speed, while it goes up and down.
    I'm not speaking about the horizontal or the vertical vectors of the sine wave.
    I 'm speaking about the fixed orbital speed of the Sun.
    Is it clear to you?
    Do you still believe that I do not understand in vectors?
    Yes, based on that answer, I still believe you don't understand vectors.

    Please answer my direct question, previously asked: As the sun moves around the galaxy, does it also move upwards (away from the galactic midplane), and then stop moving upwards, and then move downwards?

    Grant Hutchison
    Last edited by grant hutchison; 2018-Jan-08 at 01:08 PM.

  17. #77
    Join Date
    Sep 2015
    Posts
    302
    Quote Originally Posted by grant hutchison View Post
    Yes, based on that answer, I still believe you don't understand vectors.

    Please answer my direct question, previously asked: As the sun moves around the galaxy, does it also move upwards (away from the galactic midplane), and then stop moving upwards, and then move downwards?

    Grant Hutchison
    I'm not sure that I fully understand your question.

    The Sun orbits around its Trojan point.
    The Trojan point is located at the galactic plane.
    However, due to the orbital cycles, the sun goes up and down in a sinusoidal wave.
    Therefore, the sun moves upwards (away from the galactic midplane), and then stop moving upwards, and then move downwards.

    Did I answer your question?
    Last edited by Dave Lee; 2018-Jan-08 at 01:49 PM.

  18. #78
    Join Date
    Jul 2005
    Posts
    15,048
    Quote Originally Posted by Dave Lee View Post
    I'm not sure that I fully understand your question.

    The Sun orbits around its Trojan point.
    The Trojan point is located at the galactic plane.
    However, due to the orbital cycles, the sun goes up and down in a sinusoidal wave.
    Therefore, the sun moves upwards (away from the galactic midplane), and then stop moving upwards, and then move downwards.

    Did I answer your question?
    If we ignore your supposed explanation for the movement, your last line answers my question. (The combined motions you describe will actually result in a trochoidal curve, not a sinusoid.)

    So as the sun moves around the galaxy, it also goes up, stops moving upwards, and then comes down again.
    And as the ball in Jens's example moves from thrower to catcher, it also goes up, stops moving upwards, and then comes down again.

    Direct question: Do you agree with that?

    Grant Hutchison

  19. #79
    Join Date
    Sep 2015
    Posts
    302
    Quote Originally Posted by grant hutchison View Post
    If we ignore your supposed explanation for the movement, your last line answers my question. (The combined motions you describe will actually result in a trochoidal curve, not a sinusoid.)

    So as the sun moves around the galaxy, it also goes up, stops moving upwards, and then comes down again.
    And as the ball in Jens's example moves from thrower to catcher, it also goes up, stops moving upwards, and then comes down again.

    Direct question: Do you agree with that?

    Grant Hutchison
    As I have explained, there are only two stady state cases for Gravity.
    The first one is orbital, the second is direct contact.

    With regards to your following explanation:

    Quote Originally Posted by grant hutchison View Post
    Really simple argument:
    Imagine a thick disc of uniform density.
    Place an object in the geometrical centre of this disc. The object is surrounded by an equal mass distribution in all directions, so the net gravitational force on it must be zero.
    Move the object to the surface of the disc, again centred. The object now has all the mass distributed below it, and none above, so the net gravitational force must be non-zero, and directed towards the disc.

    Therefore, if we move the object from the geometrical centre of the disc to the centre of its surface, the gravitational force it experiences must increase from zero to some non-zero value.

    Although the sun is not at the centre of the galaxy, the same argument applies - the gravitational force now resolves into a radial force (which keeps the sun in orbit around the galaxy) and a force normal to the plane of the galaxy, which is zero when the sun is in the midplane, and which increases as it moves away from the midplane, pulling the sun back towards the midplane.

    Grant Hutchison

    If I understand you correctly, your message is as follow:

    Let's set the Sun at the Galactic plane.
    Lets set N number of stars around it at a fixed distance, so the gravity power from the one infront will be canceled by the one in the back.
    Therefore, the total Gravity power on the Sun at the Galactic plane will be Zero.

    Let me start by asking the following question:
    Around which point the Sun orbits. (Where is its primary point?)
    Is it the center of the Galaxy, one of those stars or some other point?
    Last edited by Dave Lee; 2018-Jan-08 at 03:33 PM.

  20. #80
    Join Date
    Jul 2005
    Posts
    15,048
    Quote Originally Posted by Dave Lee View Post
    As I have explained, there are only two stady state cases for Gravity.
    The first one is orbital, the second is direct contact.

    With regards to your following explanation:




    If I understand you correctly, your message is as follow:

    Let's set the Sun at the Galactic plane.
    Lets set N number of stars around it at a fixed distance, so the gravity power from the one infront will be canceled by the one in the back.
    Therefore, the total Gravity power on the Sun at the Galactic plane will be Zero.

    Let me start by asking the following question:
    Around which point the Sun orbits. (Where is its primary point?)
    Is it the center of the Galaxy, one of those stars or some other point?
    You're still treating gravity as if it were a central force, which, in the case of the galactic disc, it is not, as has been explained to you. So your questions are based on a false assumption (that there is a unique point around which the sun orbits), and so are ill-posed, and so cannot be answered, in the same way it's impossible to answer the question, "What kind of cat is a dog?"

    Please answer my previous direction question:
    Quote Originally Posted by grant hutchison View Post
    So as the sun moves around the galaxy, it also goes up, stops moving upwards, and then comes down again.
    And as the ball in Jens's example moves from thrower to catcher, it also goes up, stops moving upwards, and then comes down again.

    Direct question: Do you agree with that?
    Grant Hutchison
    Last edited by grant hutchison; 2018-Jan-08 at 04:42 PM.

  21. #81
    Join Date
    Aug 2008
    Location
    Wellington, New Zealand
    Posts
    3,581
    Quote Originally Posted by Dave Lee View Post
    ...The Sun orbits around its Trojan Point.
    The Sun does not have a "Trojan Point" and so cannot orbit it.
    The Sun orbits around the center of mass of all of the stars within its orbit around the galaxy with an influence by the mass of stars outside of the orbit. This is an orbit in three dimensions. The Sun is not orbiting exactly parallel to the galaxy disk. It falls "below" the disk and gravity then pulls it up. It climbs "above" the disk and gravity pulls it down. Thus the orbit is a "sinusoidal wave" going up and down though the disk.
    Last edited by Reality Check; 2018-Jan-08 at 10:10 PM.

  22. #82
    Join Date
    Aug 2008
    Location
    Wellington, New Zealand
    Posts
    3,581
    Quote Originally Posted by Dave Lee View Post
    If you wish to stay in the galaxy, you have only two options:
    There is not such thing as a Trojan point. Trojan objects in the Solar System orbit around Lagrange points.
    The Sun is a star. The Sun orbits around an "other object" - all of the stars inside its orbit.

    Please remember that if we throw a tennis ball "out from the Arm" it does not leave the galaxy or even the Earth!
    More seriously you are still forgetting about gravity and escape velocity. In order for a star to leave the galaxy it has to have a velocity that is greater then the galaxy escape velocity. Without specifying this your post is wrong.

  23. #83
    Join Date
    Aug 2008
    Location
    Wellington, New Zealand
    Posts
    3,581
    Quote Originally Posted by Dave Lee View Post
    Let's set the Sun at the Galactic plane.
    Lets set N number of stars around it at a fixed distance,..
    This is not a reasonable approximation because the Sun is not surrounded by stars at a fixed distance.
    Let us set N number of stars around the Sun in a uniform disk with the Sun located near the outer edge. There are more stars inside the Sun's location than outside. The force of gravity of each star beyond the Sun's location is cancelled out by a star inside the location. That leaves a net gravitational force from the not-paired stars inside the Sun's location. If the Sun starts from rest, the Sun must "fall" toward the center of the Milky Way. Add a "horizontal" velocity and like all objects in a gravitational field we have an orbit. The orbit is around a center of mass of the unpaired stars - approximately an empty point near the center of the Milky Way.

    We can add a galactic bulge and that net gravitational force increases.

    IF01: What does the Sun orbit around in your ATM idea (show your work)?
    The answer will not be yet another unsupported "Trojan Point" assertion - you need show your calculation of the net gravitational force on the Sun from all of the other stars in the galaxy, that this creates a Lagrange point, and that the Sun is a Trojan object orbiting that Lagrange point.
    Last edited by Reality Check; 2018-Jan-08 at 10:38 PM.

  24. #84
    Join Date
    Jul 2005
    Posts
    15,048
    Quote Originally Posted by Reality Check View Post
    There is not such thing as a Trojan point.
    Well, "Trojan point" is a common enough expression to designate the triangular Lagrange points, and it appears in papers written by academic astronmomers. Here's just the first example I find in my bookmarks which happens to have "Trojan points" in the abstract: http://www.sciencedirect.com/science...19103508003862
    If it's good enough for Icarus, it's probably good enough for us.

    Grant Hutchison

  25. #85
    Join Date
    Jun 2007
    Posts
    5,512
    Quote Originally Posted by Dave Lee View Post
    As I have explained, there are only two stady state cases for Gravity.
    The first one is orbital, the second is direct contact.
    That isn't even wrong. Gravity doesn't have states. Objects in orbit are in freefall, moving under the influence of the gravity of all the masses around them. Objects resting on the ground are subject to exactly the same gravitational force, they're just experiencing additional forces due to their contact with the ground. There is no "steady state" for gravity, there's just gravity.

    You seem to have some notion that gravity makes things circle around some specific point, ignoring everything else. That isn't at all the way it works.

  26. #86
    Join Date
    May 2005
    Posts
    7,767
    Quote Originally Posted by grant hutchison View Post
    Well, "Trojan point" is a common enough expression to designate the triangular Lagrange points, and it appears in papers written by academic astronmomers. Here's just the first example I find in my bookmarks which happens to have "Trojan points" in the abstract: http://www.sciencedirect.com/science...19103508003862
    If it's good enough for Icarus, it's probably good enough for us.
    And, the Trojan point is not an "attractor" in the gravitational sense. It is the top of a hill in the potential, just the opposite of planetary bodies that reside in valleys of the potential.

  27. #87
    Join Date
    Sep 2015
    Posts
    302
    Quote Originally Posted by grant hutchison View Post
    If we ignore your supposed explanation for the movement, your last line answers my question. (The combined motions you describe will actually result in a trochoidal curve, not a sinusoid.)

    So as the sun moves around the galaxy, it also goes up, stops moving upwards, and then comes down again.
    And as the ball in Jens's example moves from thrower to catcher, it also goes up, stops moving upwards, and then comes down again.

    Direct question: Do you agree with that?

    Grant Hutchison

    Sorry.
    There is no difference in the rolls between moon, planet or Star in the galaxy.
    There is no VIP in the system.
    If you want to be part of the galaxy, you must obey to the same rolls (even if we call you Star or Sun)!

    Please look at the following diagram of orbital path of the Moon:

    https://www.quora.com/Does-the-moon-...around-the-sun

    https://www.quora.com/Does-the-moon-...around-the-sun

    That gives a clear image how the moon revolve around the Sun.
    As you can see it set the same sine wave, Up and down.

    We could say:
    "So as the Moon moves around the Sun, it also goes up, stops moving upwards, and then comes down again."
    So what?
    Don't you see its sine wave?

    All the objects in the system must obey to the same rolls.
    Even if you are an Asteroid.
    You have to revolve around other object as Moon, Earth, star or center of mass point!!!
    You can collide with that object and set a direct contact, but if you disconnect yourself, you are out of the System.

    The Sun revolves in the galaxy in the same path as the Moon revolve around the Sun.
    The only difference in the Sine wave is the Amplitude and the rotation Phase.

    Please try to find even one planet or moon (in the whole galaxy) which does not revolve around another object.
    You won't find! Never, Ever!

    In the same token, all the objects in the galaxy (including the Sun) must revolve around some center of mass.
    I have called it Trojan Point, you can call it primary point.
    The name does not change the reality.
    If you wish to be free, if you don't want to set a direct contact and still stay in the galaxy, than you must run for your life.
    You must revolve around your primary point or center of mass.
    Without it, you are a spaceship.
    You can go anywhere, but no one is going to hold you in the system.
    There is no free lunch in the galaxy.
    Last edited by Dave Lee; 2018-Jan-09 at 06:17 AM.

  28. #88
    Join Date
    Mar 2003
    Posts
    2,884
    Quote Originally Posted by Dave Lee View Post
    Please look at the following diagram of orbital path of the Moon:

    https://www.quora.com/Does-the-moon-...around-the-sun

    That gives a clear image how the moon revolve around the Sun.
    As you can see it set the same sine wave, Up and down.

    That (simplified) diagram shows the orbit of the moon around the Sun (travelling in conjunction with the Earth, which is not shown). It does not represent any "up and down" motion equivalent to the bobbing motion of the sun as it passes up and down through the galactic plane. There is NO equivalence in your example.

    We could say:
    "So as the Moon moves around the Sun, it also goes up, stops moving upwards, and then comes down again."
    So what?
    Don't you see its sine wave?
    Except the diagram you link to is a simplified diagram of the moon's orbit around the sun shown in one plane. We are talking about the sun orbiting around the galaxy while also bobbing up and down in a second plane - much like a carousel horse moving up and down while going around the carousel in a circle.

    In the same token, all the objects in the galaxy (including the Sun) must revolve around some center of mass.
    I have called it Trojan Point, you can call it primary point.
    You are taking a three-body gravitational situation and are trying to apply that to a system of some 400 billion stars, dark matter, gas & dust, etc. Do you see where you may encounter problems trying to force an equivalence?

  29. #89
    Join Date
    Feb 2014
    Posts
    192
    Quote Originally Posted by Dave Lee View Post
    Sorry.
    ....
    I have called it Trojan Point, you can call it primary point....
    Is this just a nomenclature thing? Trojans and Lagrange points have existing precise definitions, so you invite confusion at best if you start making up new definitions for these words.

  30. #90
    Join Date
    Oct 2009
    Location
    a long way away
    Posts
    10,034
    Quote Originally Posted by Dave Lee View Post
    The Sun revolves in the galaxy in the same path as the Moon revolve around the Sun.
    Not really. The galaxy is more complex, gravitationally. It is not just a central point that the Sun orbits. The Sun does orbit around the centre of the galaxy, in a roughly circular motion. This is separate from its motion above and below the galactic disk, which is caused by the mass of the disk and this cannot be treated the same way as one body orbiting another.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •