It's not rocket science

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Manc33
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Re: It's not rocket science

Postby Manc33 » 16 Nov 2019, 5:36pm

[XAP]Bob wrote:Assuming you are detaching your back from your body and throwing it.... it isn’t at all.


:lol:

Humour aside, that's my point. You're not detaching the rocket nozzle from the rocket and throwing it.

Also from earlier... I don't deny the existence of an effect we call gravity, the part I deny is the claim that mass is attracting mass. An effect does exist because different densities separate out into layers and something has to be causing that.
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[XAP]Bob
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Re: It's not rocket science

Postby [XAP]Bob » 16 Nov 2019, 5:43pm

No, you’re detaching the exhaust gassed and the nozzle is the equivalent of your hand pushing it.
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roubaixtuesday
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Re: It's not rocket science

Postby roubaixtuesday » 16 Nov 2019, 5:44pm

Manc33 wrote:Humour aside, that's my point. You're not detaching the rocket nozzle from the rocket and throwing it.


But you are detaching molecules of exhaust gas and throwing them.

Again, what is the difference between throwing a gas molecule out of the back of a rocket and catapulting a ball?

Why do you claim the latter, but not the former causes a recoil?

[Edit - see Bob has made the same point. Any chance of an answer, Manc?]

Manc33
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Re: It's not rocket science

Postby Manc33 » 17 Nov 2019, 2:16pm

Maybe it can work like that but this is all theoretical while there's no proof it's happening.

All I need now is solid evidence these things are flying around in a 2nd law of thermodynamics violating vacuum next to gas pressure without a container - evidence (although not proof) would be something like a rocket blasting in space and speeding up, but filmed from afar (not from a camera that's right up against the rocket 1 inch away from it like has been shown in the past).

You'd think there'd be something in space with a camera on it able to see rockets blasting into space from the earth, hundreds of miles above it. Every rocket I have seen curves and ends up horizontal. I think they just get dumped into the sea and nothing is going into space, how can anything go into space at all when to have a gas pressure next to a vacuum and have it magically maintain itself without ever equaling out is violating the 2nd law of thermodynamics.

People can romance about gravity holding the air down but if it gravity was that powerful, we wouldn't have the strength to freely move around like we do. Cycling wouldn't even exist. We would all weigh ten times more. The notion that gravity strongly welds the air to the earth (to the point it can even negate gas pressure) is lunacy.
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kwackers
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Re: It's not rocket science

Postby kwackers » 17 Nov 2019, 3:16pm

Manc, you keep going on about violating the second law of thermodynamics, gas next to a vacuum etc etc.

You realise that gravity negates all that. Gravity is why stuff clings to itself and why gas can't escape into the vacuum.
A vacuum isn't even that great a pressure, it's just one atmosphere, 15lbs per sq inch, a tenth what my compressor manages.

Mass attracts mass - magnetism on a teeny scale and with a teeny tiny the amount of attraction a magnet would have - so little in fact you need a lot of mass before it becomes measurable.

Why do you have so much trouble accepting that one thing?
Everything works once you do, the maths just falls out because it's right.

Your "solutions" to not having gravity can't even co-exist with each other.


Ultimately though I think you need to realise you've joined a cult and until you do then you're lost because you'll never accept any explanation you don't like.

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[XAP]Bob
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Re: It's not rocket science

Postby [XAP]Bob » 17 Nov 2019, 3:40pm

You mean like the footage of the TLI burn from the Apollo missions?
A shortcut has to be a challenge, otherwise it would just be the way. No situation is so dire that panic cannot make it worse.
There are two kinds of people in this world: those can extrapolate from incomplete data.

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[XAP]Bob
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Re: It's not rocket science

Postby [XAP]Bob » 17 Nov 2019, 3:57pm

Manc33 wrote:Maybe it can work like that but this is all theoretical while there's no proof it's happening.

There is proof - look at the satellites we have in orbit, how did they get there?
Look at the footage of any of the berthings or docking at the ISS, watch any rocket launch.

All I need now is solid evidence these things are flying around in a 2nd law of thermodynamics violating vacuum next to gas pressure without a container - evidence (although not proof) would be something like a rocket blasting in space and speeding up, but filmed from afar (not from a camera that's right up against the rocket 1 inch away from it like has been shown in the past).

You'd think there'd be something in space with a camera on it able to see rockets blasting into space from the earth, hundreds of miles above it. Every rocket I have seen curves and ends up horizontal. I think they just get dumped into the sea and nothing is going into space, how can anything go into space at all when to have a gas pressure next to a vacuum and have it magically maintain itself without ever equaling out is violating the 2nd law of thermodynamics.

Why would we go to the expense of putting cameras in space to watch something we can see from the ground. Yes, rockets go horizontally, because that’s the direction of an orbit. If you don’t go sideways then you’ve just made a sounding rocket, not an orbital one.
https://what-if.xkcd.com/58/

People can romance about gravity holding the air down but if it gravity was that powerful, we wouldn't have the strength to freely move around like we do. Cycling wouldn't even exist. We would all weigh ten times more. The notion that gravity strongly welds the air to the earth (to the point it can even negate gas pressure) is lunacy.

Erm - what?

Gravity produces a consistent acceleration of 9.8m/s/s... that ends up with about 1kg of air over every square centimetre of the earths surface - which we feel as atmospheric pressure.
Why would be unable to move if gravity is strong enough to deflect the course of a molecule?
Last edited by [XAP]Bob on 18 Nov 2019, 1:16pm, edited 1 time in total.
A shortcut has to be a challenge, otherwise it would just be the way. No situation is so dire that panic cannot make it worse.
There are two kinds of people in this world: those can extrapolate from incomplete data.

roubaixtuesday
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Re: It's not rocket science

Postby roubaixtuesday » 17 Nov 2019, 4:22pm

Manc33 wrote:People can romance about gravity holding the air down but if it gravity was that powerful, we wouldn't have the strength to freely move around like we do. Cycling wouldn't even exist. We would all weigh ten times more. The notion that gravity strongly welds the air to the earth (to the point it can even negate gas pressure) is lunacy.


1. I note you have not answered the question as to why you believe a catapult will recoil in a vacuum, but molecules being thrown out of a rocket will not.

Please answer.

2. Up thread I posted the velocity distribution of gas molecules and the escape velocity from earth. The escape velocity being far higher than the fastest molecules is a very simple explanation on why gravity does, indeed, hold the atmosphere to the surface.

Please explain, with numbers rather than rhetoric, why that explanation is false.

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[XAP]Bob
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Re: It's not rocket science

Postby [XAP]Bob » 17 Nov 2019, 9:34pm

You also seem fixated on this concept that the atmosphere has an edge....
A shortcut has to be a challenge, otherwise it would just be the way. No situation is so dire that panic cannot make it worse.
There are two kinds of people in this world: those can extrapolate from incomplete data.

Mike Sales
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Re: It's not rocket science

Postby Mike Sales » 17 Nov 2019, 9:50pm

One thing that always strikes me about space, is how close it is
Of course the atmosphere attenuates slowly, so it depends how you define the edge of it.
One accepted definition puts it as 100K away, which would be a fairly easy bike ride, were it horizontal not vertical.
The International Space Station is 354K up, also rideable.
Boats deep in the Southern Ocean, between NZ and South America are sometimes able to say that the nearest person is in the ISS.
The atmosphere really is a thin shell. Even at 8K, the height of Everest is becoming dangerously thin for us.

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[XAP]Bob
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Re: It's not rocket science

Postby [XAP]Bob » 17 Nov 2019, 10:16pm

Fun videos:

Time-lapse of a Soyuz launch as seen from the ISS...


Scott Manley explaining where the TLI burn footage from the Apollo 11 documentary came from (footage of a rocket lighting it's engine in space and accelerating at about 3:30)


Of course the *most* famous footage of a rocket engine igniting and accelerating a vehicle in a vacuum is this:
A shortcut has to be a challenge, otherwise it would just be the way. No situation is so dire that panic cannot make it worse.
There are two kinds of people in this world: those can extrapolate from incomplete data.

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[XAP]Bob
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Re: It's not rocket science

Postby [XAP]Bob » 17 Nov 2019, 10:19pm

Also good to understand how the light works:


And at about 3:40 you see the cold gas thrusters which are used to flip the first stage around for it's return to land at sea (in this case) or back at LZ1 (for relatively low dV payloads launched from the east coast)
Last edited by [XAP]Bob on 18 Nov 2019, 1:13pm, edited 1 time in total.
A shortcut has to be a challenge, otherwise it would just be the way. No situation is so dire that panic cannot make it worse.
There are two kinds of people in this world: those can extrapolate from incomplete data.

mattheus
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Re: It's not rocket science

Postby mattheus » 18 Nov 2019, 10:02am

Mike Sales wrote:One thing that always strikes me about space, is how close it is
Of course the atmosphere attenuates slowly, so it depends how you define the edge of it.
One accepted definition puts it as 100K away, which would be a fairly easy bike ride, were it horizontal not vertical.
The International Space Station is 354K up, also rideable.
Boats deep in the Southern Ocean, between NZ and South America are sometimes able to say that the nearest person is in the ISS.
The atmosphere really is a thin shell. Even at 8K, the height of Everest is becoming dangerously thin for us.


Yes - it's not just me then!!! I've ridden 354k in a day (not very often, I should stress)

(I get a similar things with clouds - surely they're part of the sky, you know Way Up There. Not something we can touch.

This despite having often been above clouds (on hills, or in a plane). The brain does funny things ... )

Manc33
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Re: It's not rocket science

Postby Manc33 » 18 Nov 2019, 1:23pm

Bob you said this:

[XAP]Bob wrote:You also seem fixated on this concept that the atmosphere has an edge....


Then posted this:

Image

The atmosphere has a hard line to it on that video.

To me it looks like special effects. I'm not saying it is faked but because it can be faked, it's not proving it.

Ever seen the footage of Tim Peake doing a somersault and something snapped?

I thought people were supposed to be weightless in space? :wink:

Skip to 3:05
https://www.youtube.com/watch?v=RYJhYbuk3Ms

Apart from the fact that you can see the wire under his trousers, he suddenly moves and something makes a noise. Maybe it was a "gravity pocket" in space :roll: :lol:

There's way more than that, the one with a guy on a harness just swinging past in the background on the ISS, comedy gold... look at 18 seconds in...

https://www.youtube.com/watch?v=_hV6WUAN7v0

Did they forget they were filming? This stuff is an absolute joke.

The offending screenshots...

Image

Image
Last edited by Manc33 on 18 Nov 2019, 1:30pm, edited 1 time in total.
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[XAP]Bob
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Re: It's not rocket science

Postby [XAP]Bob » 18 Nov 2019, 1:23pm

Manc33 wrote:
[XAP]Bob wrote:Assuming you are detaching your back from your body and throwing it.... it isn’t at all.


:lol:

Humour aside, that's my point. You're not detaching the rocket nozzle from the rocket and throwing it.

Also from earlier... I don't deny the existence of an effect we call gravity, the part I deny is the claim that mass is attracting mass. An effect does exist because different densities separate out into layers and something has to be causing that.


The Newtonian approximation is that mass attracts mass. The current best understanding of gravity is actually that mass distorts four dimensional space time, and objects follow a straight line along the higher dimension curvature in space time.
However I doubt that your doubt is based on an understanding of general relativity (as opposed to special relativity)
A shortcut has to be a challenge, otherwise it would just be the way. No situation is so dire that panic cannot make it worse.
There are two kinds of people in this world: those can extrapolate from incomplete data.