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Newton's (F)laws (Astrophysics)
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Brian Ambrose



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Ishmael wrote:
Komorikid wrote:
...and it can easily be proved to be wrong.


Yet several generations have somehow failed to notice -- until now!


What puzzles me is that, given Newton's glaring errors, how we ever manage to hit those specks of dirt in the vast distances of space with our spacecraft.
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May I remind you all of our firm rule NOT to attack new theories. If you must reprove, do it in the most encouraging way you can.
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Komorikid


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Brian wrote:
So we are using a point in the Milky Way galaxy as a reference.

No we are talking about the Sun as a reference point.

Not really. Relative to the Milky Way, the Earth is moving in the same 'direction' as the Sun the whole time (albeit that 'direction' is constantly changing by a tiny amount). It has to move a little faster than the Sun for half the time (to get 'ahead' of it), and a little slower than the Sun for the other half (to get 'behind' it).

The Earth's orbit is relative to the Sun. The Sun's orbit with its complement of planets is orbiting the Milky Way. The Earth's relationship to the Sun doesn't change because The sun et al. is orbiting the Milky Way. The Sun is travelling in one direction. The Earth in its orbit is travelling in the same direction to the Sun for half its orbit and against the direction of the Sun for the other half of its orbit. The Earth is travelling at the same rate in both direction. As the Earth is travelling away from the Sun the Sun closes the distance but as the Earth travels towards the sun the distance lengthens.

Relative to the centre of the galaxy - yes (but this 3rd party influenced effect is hardly what Kepler had in mind). Relative to the Earth - no.

Relative to the Sun -- Yes

Yes - it has to 'overtake' the Sun.

No -- the distance increases because the Sun is also moving in the same direction.

Er, no. The solstices do not depend on the nearest/furthest points of the Earth's orbit, but at the points where the Earth's axis is aligned with the Sun. The northern hemisphere's summer solstice is the southern's winter solstice.

Well I was being charitable to Kepler. The time difference between aphelion and perihelion is actually 72 hours a day longer than the Solstices.

I'm not sure of the relevance of this - if the Earth travels slightly faster (relative to the Sun) between two (geometrically fixed) absolute points (the solstices), is that not compatible with the Earth having a Keplerian elliptical orbit? Again, there is no reason why the solstices should match the periapsis/apoapsis of the Earth's orbit (is there?).

The Earth doesn't travel slightly faster or slower, it travels at the same rate but sweeps out equal areas in unequal times.

As far as I can tell, Kepler's law says that the further the planet is from the Sun, the slower it moves - which is why the area it covers stays equal to an area caused by a smaller radius, which requires a further distance to be travelled - ie planet travels faster. This is exactly what Newton proposed. As for planets travelling slower in winter, and the winter solstice being closest to the Sun, I think this is incorrect, if only in that closeness to the Sun and solstice are not the same thing.

No, Kepler noted that planets and the Moon, according to Brahe's calculations, (which is what Kepler used remember) moved slower in WINTER and faster in SUMMER.
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Komorikid


In: Gold Coast, Australia
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Brian wrote:

What puzzles me is that, given Newton's glaring errors, how we ever manage to hit those specks of dirt in the vast distances of space with our spacecraft.


We didn't at first.
That is when NASA and the Russians realised that celestial mechanics calculations didn't work. In the early space race there were some spectacular misses. None more spectacular than the Russians missing the moon by over 100,000 miles.

There isn't a space probe in the solar system that isn't constantly being course corrected by onboard stellar fixes and ground based radiometric ranging. There are at least 12 long range space vehicles that are suffering positioning 'anomalies'. The furthest, Voyager and Pioneer, are hundreds of thousands of miles off course from where standard celestial mechanics says they should be.

Imagine the furore in the US if NASA had to admit its basis for sending billion dollar project into space was based on a error.
We just had the scandal over the Stefan-Boltzmann law which NASA realised was useless for a three dimensional environment viz-a-viz the Apollo landings on the Moon. They kept their revised calculations that applied to the real environment secret for 40 years and when NASA became the resource for Global Warming modeling, which require the S-B law to produce radiative forcing. They relied on original law for the models which they knew was inappropriate.
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Komorikid


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Grant wrote:

The depiction of Newton as an ambitious social climber doesn't fit the facts. He spent more time studying the Bible than he did promoting himself or running the mint.


Let's see how this stacks up

*He tried to set up his own Royal Society with the help of Charles Montague
*He is given the job of Master of the Mint by his friend Montague who becomes King William's main advisor.
*He gains control of the Royal Society with Montague's assistance
*He rubber stamps his own theory of light when he becomes head of the Royal society.
*He has all memory of Robert Hooke erased from the Society
*He uses a iron mace instead of a wooden hammer as a gavel.
*He chairs the 'independent' inquiry to decide who invented Calculus and decides that he did despite Leibniz prior claim.

Just when did all this bible study take place.
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Grant



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Just when did all this bible study take place.


Don't know, but to quote his Wiki biography:

His scientific fame notwithstanding, Newton's studies of the Bible and of the early Church Fathers were also noteworthy. Newton wrote works on textual criticism, most notably An Historical Account of Two Notable Corruptions of Scripture. He also placed the crucifixion of Jesus Christ at 3 April, AD 33, which agrees with one traditionally accepted date.[71] He also tried, unsuccessfully, to find hidden messages within the Bible.

Newton wrote more on religion than he did on natural science.
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Grant



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He is given the job of Master of the Mint by his friend Montague who becomes King William's main advisor.


But this job was given to him as a reward for his fame and was intended to be a sinecure. Newton, though, was an obsessive - today they would probably say he had Asperger's - and he decided to take the job seriously. He became obsessed with it the way he was previously obsessed with maths, then physics, alchemy, the nature of the Trinity, and his own reputation.
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Brian Ambrose



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Hi KK.

No, we are talking about the Sun as a reference point


Then I don't understand why you need to mention the Milky Way at all. Either you are interested in the motions of both the Sun and the Earth relative to the Milky Way, or you can take the Sun as your point of reference. Since you are taking the Sun as your reference, its motion around the Milky Way (and the Milky Way's own orbit around something else, and so on) is irrelevant.

The Sun is travelling in one direction.

But you just said we are talking about the Sun as a reference point. If it is a reference point then we cannot say that it is travelling anywhere. If the Sun is 'travelling', then it must be doing so relative to something else. Since you previously mentioned the Milky Way, I'm going to assume that that is your reference. But this ambiguity doesn't help your argument.

The Earth in its orbit is travelling in the same direction to the Sun for half its orbit and against the direction of the Sun for the other half of its orbit.

As I said before, the Earth cannot possibly travel in the opposite direction that the Sun is travelling. It can only travel more slowly than the Sun in the same direction that the Sun is travelling.

The Earth is travelling at the same rate in both directions. As the Earth is travelling away from the Sun the Sun closes the distance but as the Earth travels towards the sun the distance lengthens.

I'm sorry, but this is makes no sense, whether I take the Milky Way as the reference, or the Sun as the reference.

Well I was being charitable to Kepler. The time difference between aphelion and perihelion is actually 72 hours a day longer than the Solstices....The Earth doesn't travel slightly faster or slower, it travels at the same rate but sweeps out equal areas in unequal times.

Which is to completely miss the point I made. Your 'proof' only works if the solstices are synchronised to aphelion and perihelion - they are not.

No, Kepler noted that planets and the Moon, according to Brahe's calculations, (which is what Kepler used remember) moved slower in WINTER and faster in SUMMER.

As I said, I don't know what this means - are you talking about Australian winters or British winters? Do planets move slower in Australia's summer? Please explain.
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Brian Ambrose



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KK said:

the Russians realised that celestial mechanics calculations didn't work.


What imperative do you suggest made the USSR keep it a secret that the West's most respected scientist not only got it wrong, but spectacularly so? Or is it rather more likely that they had the correct calculations, but it was their technology that wasn't good enough?
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Komorikid


In: Gold Coast, Australia
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As I said before, the Earth cannot possibly travel in the opposite direction that the Sun is travelling. It can only travel more slowly than the Sun in the same direction that the Sun is travelling.


Let me make this as simple as I can. Two bodies are aranged thus:

O < O

The large body is moving to the left with the smaller body orbiting it in a counter clockwise direction. As the orbiting body orbits from the 9 o'clock position to the 3 o'clock position it is moving in the opposite direction to the direction of travel of the larger body. As the orbiting body orbits from the 3 o'clock position to the 9 o'clock position it is moving in the same direction to the larger body.

Yes they are both moving very slowly to the left in relation to the Milky Way but the Earth orbit is determined by the Sun not the galaxy they are both embedded in.
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Komorikid


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Brian wrote:

As I said, I don't know what this means - are you talking about Australian winters or British winters? Do planets move slower in Australia's summer? Please explain.


Kepler's measurements of Mars and Brahe's measurements of the Moon showed they were slowing down in winter. That's the northern hemisphere winter where the measurements were taken from. Don't shoot the messenger. I am only telling you what their respective measurements showed.
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Komorikid


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Brian wrote:

What imperative do you suggest made the USSR keep it a secret that the West's most respected scientist not only got it wrong, but spectacularly so? Or is it rather more likely that they had the correct calculations, but it was their technology that wasn't good enough?


It was called the Cold War.
You honestly think the Russians were going to blab about finding an error in celestial mechanics as their enemy were planning a manned mission to the Moon. Their first German scientist to open his mouth would have been dead minutes later.
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Komorikid


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Brian wrote:

Which is to completely miss the point I made. Your 'proof' only works if the solstices are synchronised to aphelion and perihelion - they are not.


My proof works either way.

Perihelion to aphelion = 184 days
Aphelion to perihelion = 181 days
Summer Solstice to Winter Solstice = 183 days
Winter Solstice to Summer Solstice = 181 days

Therefore a line connecting the Sun and the Earth sweeps out Equal areas on UNEQUAL times.

I don't need a stick in the ground or mathematical equations. I just need to count the days.

Kepler was wrong.
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Brian Ambrose



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KK said:

Perihelion to aphelion = 184 days
Aphelion to perihelion = 181 days

Therefore a line connecting the Sun and the Earth sweeps out Equal areas on UNEQUAL times.


But haven't you already pointed out that the two areas are not the same? Since the Sun is moving (and not necessarily just around the Milky Way - I have mentioned here before that it may well be in orbit around a binary companion, which better explains 'precession'). If the Sun is moving, would you not expect the areas covered to be different, and therefore the times different? That is, do Kepler's perfect elipse models apply when another acceleration is introduced?
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Brian Ambrose



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KK said:

It was called the Cold War.


Which has been over for 20 years. So ever since, the Russians have been in collusion with the... er, with everybody... to keep this failure of Newton's laws secret from... everybody else... because they are embarrassed in case anybody finds out that 40 years ago they didn't know as much as everyone thought they knew?
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