Relativity Specialist

If NASA faked the moon landings, does the agency have any credibility at all? Was the Space Shuttle program also a hoax? Is the International Space Station another one? Do not dismiss these hypotheses offhand. Check out our wider NASA research and make up your own mind about it all.

Relativity Specialist

Postby pmb on July 22nd, 2015, 10:10 pm

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ADMIN: This thread was split from the Rocketry thread for being off-topic and for giving us a number of different things to think about. It is based on the membership of a "pmb" who joined and said they are a specialist in relativity, and they claim to have done work for a NASA project. CluesForum invites you to read on, in order to see if you can learn anything about this special specialist on special relativity that NASA apparently hired. -HP



Selene wrote:Hi Pete, welcome to Cluesforum. Have you read quite a bit before registering?

Since there are 522 posts I didn't think it would be a good way to spend my time reading all of them. I just skimmed through them.

Selene wrote:On satellites ("geostationary" and others) there's a separate thread where you find info on how to obtain the huge amounts of satellite data and signals (including your DirectTV) we receive on Earth.

Can you point me to one?

Selene wrote:As a physicist you also should know one doesn't need a 50x50 cm mirror to bounce back signals (radio waves, lasers or sunlight) from the surface of the Moon; the celestial body itself reflects signals easily, otherwise they wouldn't be able to do so before the Apollo "moon" missions (1963 the Soviets did it and radio wave bouncing was done already in 1946 (!) and you wouldn't be able to see a thing at nights with (full) Moonlight...

As a physicist I know that such a thing is quite literally impossible. The laser beam would be so week after traveling only a mile that it'd be impossible to detect it after another 250,000 miles. Perhaps you're thinking of sunlight bouncing off the regolith? You're confusing bouncing a radar beam with bouncing a laser beam. They are radically different problems due to the radically different wavelengths.

Selene wrote:As a physicist you know that material properties are highly T-dependent, so a "rocket" in "space" would have the problem that ~50% of the surface (sun-lit) suffers from very high T's (due to radiation) and the other half or even more of the "rocket" would suffer near-zero T's.

That's not a problem. There's heat shielding to take care of that. You've made a lot of statements here but have you ever made any calculations to back up your qualitative assertions?

Selene wrote:Take the thermal conductivity for instance. Could you as physical expert make a calculation on how this works?

What's there to know? Matter is composed of atoms and molecules. The composition of the matter in those terms determines the conductivity. How exactly that's done is very hard to calculate and requires someone who specializes in that field. Not all physicists know all branches of physics. I'll look into it though.

Selene wrote:50% aluminium rocket surface @ -let's say- +270 C and the other part at -NASA-claimed- -270 C, or some mere 3 K!

What effect should those extreme conditions have on the rocket and everything inside it, you think?

Those aren't the kind of problems that a physicist studies or solves. Those are done my physical chemists. See: https://en.wikipedia.org/wiki/Physical_chemistry

My specialty is relativity.
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Re: Does Rocketry Work in the Vacuum?

Postby Selene on July 22nd, 2015, 10:34 pm

Bummer.

If you say you specialised in "relativity" you should have a decent foundation of physics to even start, the same foundation which should permit you to do a basic calculation. And material properties are all physical-chemical, how couldn't I agree, as I stated it in the question I asked...

I do not have that many posts in the satellite topic nor here so clicking on my name should lead you to the desired ones.

A "heat shield" takes care of that, "no problem"? Would you mind providing a basic explanation in your own words on what a heat shield actually IS and DOES?

No need for a rushed answer, take your time. If you read a bit more you notice that most of the posts on this forum are well elaborated and take time and effort to make.

If you as a relative expert say that "bouncing laser signals off the Moon is impossible without a 50x50 cm mirror" [that cannot be on the Moon as nobody nor unmanned probes can get there], what and how did the Soviets actually manage to do exactly that in 1963?

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Re: Does Rocketry Work in the Vacuum?

Postby Pilgrim on July 22nd, 2015, 10:38 pm

pmb wrote:
Selene wrote:As a physicist you also should know one doesn't need a 50x50 cm mirror to bounce back signals (radio waves, lasers or sunlight) from the surface of the Moon; the celestial body itself reflects signals easily, otherwise they wouldn't be able to do so before the Apollo "moon" missions (1963 the Soviets did it and radio wave bouncing was done already in 1946 (!) and you wouldn't be able to see a thing at nights with (full) Moonlight...
As a physicist I know that such a thing is quite literally impossible. The laser beam would be so week after traveling only a mile that it'd be impossible to detect it after another 250,000 miles. Perhaps you're thinking of sunlight bouncing off the regolith? You're confusing bouncing a radar beam with bouncing a laser beam. They are radically different problems due to the radically different wavelengths.

No, M.I.T claimed they bounced a laser off the Moon in 1962, are you suggesting our esteemed pillars of American science were deceiving us back then?
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Re: Does Rocketry Work in the Vacuum?

Postby HonestlyNow on July 22nd, 2015, 10:42 pm

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Re: Does Rocketry Work in the Vacuum?

Postby Pilgrim on July 22nd, 2015, 11:11 pm

pmb wrote:
Since its very easy to show that a rocket engine works in a vacuum has anyone ever tried it? I.e. have you ever tried to build a vacuum chamber and fired a rocket engine in the vacuum chamber? Since the rocket engine would have to be small due to the large forces of pressure on such a chamber for large chambers one would have to use a very small engine. One could also model it using something other than a gas such as a chamber firing rubber pellets.
Since it's so easy perhaps you should convince us. I don't think you have covered all the angles in assuming the relative size of the propulsion unit to the size of the chamber needed.


Since things like Direct TV works by satellites and you need a satellite dish in your yard pointing at it in its geostationary position in space, how did it get there?
That's called begging the question (circular logic).. and affirming the consequent in logic and is a fallacious claim. Have you heard of ground based skywave for example? How do think the first GPS system from the the early 1940s worked?



When private corporations launch a rocket, where does it go if not into space? It should land and crash, right? Why has that never been seen? We all saw the results of it when Challenger crashed. The same thing would happen after it passed out of visual range. Has any of you ever thought of buying cheap radar equipment and tracking such a rocket launch?
Why should I assume it goes anywhere based on images on my TV screen?

Again your assuming if P then Q, Q therefore P when you have not even shown your premises to be true, let alone the
bad and fallacious logic of your argument by assumption (hardly scientific is it? from a so-called physicist but we understand you're only human and can be deceived yourself no matter your "credentials") How do I know challenger crashed? Why should I assume there are so many people in the Atlantic to witness rockets being flown into it, assuming that happens? Can I afford radar equipment to track a rocket into outer space?
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Re: Does Rocketry Work in the Vacuum?

Postby Selene on July 22nd, 2015, 11:39 pm


Thanks HonestlyNow, enjoying my holidays I am typing on a crappy smartphone, so thanks for pointing Promising Pete in the right direction.

Also I am curiously awaiting Petes reaction on my post on Temperature and more basic physics. To help him in his skimming attempts, he will be able to find it here.
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Re: Does Rocketry Work in the Vacuum?

Postby Flabbergasted on July 23rd, 2015, 12:24 am

pmb wrote:Since there were close to 400,000 scientist, engineers etc. who worked on the Apollo project in one way or another do you also hold that those 400,000 people have been lying all these years as well?
[...]
have you ever tried to build a vacuum chamber and fired a rocket engine in the vacuum chamber?
[...]
Since things like Direct TV works by satellites and you need a satellite dish in your yard pointing at it in its geostationary position in space, how did it get there?
[...]
We all saw the results of it when Challenger crashed.
[...]
How did the mirrors that are on the moon that we bounce laser beams off of get there?
[...]
Since there are 522 posts I didn't think it would be a good way to spend my time reading all of them. I just skimmed through them.

For heaven´s sake, take a month off from active CF membership and read the relevant threads. Or go skim some other forum.

pmb wrote:I'm was professional physicist until I had to retire to do becoming disabled.

Unfortunately, your disability seems to have affected your writing skills as well.
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Re: Does Rocketry Work in the Vacuum?

Postby HonestlyNow on July 23rd, 2015, 1:05 am

pmb wrote:How did the mirrors that are on the moon that we bounce laser beams off of get there?

pmb wrote:As a physicist I know that such a thing is quite literally impossible. The laser beam would be so week after traveling only a mile that it'd be impossible to detect it after another 250,000 miles.

How do you reconcile these two statements?
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Re: Does Rocketry Work in the Vacuum?

Postby simonshack on July 23rd, 2015, 1:15 am

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Dear all,

Please be nice and friendly with our new member "pmb" ( Pete). After all, he's a trained, professional physicist - and our readers should be able to learn something or the other from his contributions. Let us hear what Pete has to say, ok?

Pete has been writing quite a few e-mails to me prior to finally (after various hesitations) joining the forum. In one of his last mails he says:

pmb wrote: It's impossible for any rocket engine to operate by pushing on the atmosphere. E.g. think of the gas coming out of the nozzle. In the atmosphere all it does is push the gas of the atmosphere out of the way. However none of that force gets transmitted back to the rocket. There's just no mechanism for it.


Since I did not quite understand this concept, I encouraged Pete to post on this thread - in order to explain it for us all.

Thanks for your patience with us, Pete - we all wish to learn about physics ! :)
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Re: Does Rocketry Work in the Vacuum?

Postby pmb on July 23rd, 2015, 3:43 am

Selene wrote:If you say you specialised in "relativity" you should have a decent foundation of physics to even start, the same foundation which should permit you to do a basic calculation. And material properties are all physical-chemical, how couldn't I agree, as I stated it in the question I asked...

One of the reasons I heisted posting here was the concern that I'd get a lot of rude comments when I posted things that people don't understand. This is a good instance of it, i.e. the ignorant belief that all physicists in any field has the ability to readily whip up a calculation from any other subject in any other field. That's simply an irrational belief and very untrue. If you were a physicist you'd most certainly know that.

Selene wrote:Would you mind providing a basic explanation in your own words on what a heat shield actually IS and DOES?

You can always use the internet and look these things up? See https://en.wikipedia.org/wiki/Heat_shield

Selene wrote:If you as a relative expert say that "bouncing laser signals off the Moon is impossible without a 50x50 cm mirror" [that cannot be on the Moon as nobody nor unmanned probes can get there], what and how did the Soviets actually manage to do exactly that in 1963?

It's clear that you don't know what "specialty is relativity" means. The term "specialty" means : an area of study or business that a person specializes in or has special knowledge of. It doesn't mean expert. I don't call myself an expert for two reasons; (1) out of humility and (2) because there's always someone who thinks that "expert" means that you know every possible thing in that field that could be known, that you're knowledge is flawless and its impossible for you to make a mistake. The later is an unrealistic belief but many people have the belief when they see someone say that they're an expert. So I don't say it. However I'm very good at it.

I'm not familiar with laser ranging back in 1962 but I read something to that effect on Wikipedia just now. It also says
The distance to the Moon is calculated approximately using this equation:
Distance = (Speed of light × Time taken for light to reflect) / 2.
In actuality, the round-trip time of about 2.5 seconds is affected by the relative motion of Earth and the Moon, Earth's rotation, lunar libration, weather, polar motion, propagation delay through Earth's atmosphere, the motion of the observing station due to crustal motion and tides, velocity of light in various parts of air and relativistic effects. Nonetheless, the Earth–Moon distance has been measured with increasing accuracy for more than 35 years. The distance continually changes for a number of reasons, but averages about 384,467 kilometers.

At the Moon's surface, the beam is about 6.5 kilometers wide and scientists liken the task of aiming the beam to using a rifle to hit a moving dime 3 kilometers away. The reflected light is too weak to be seen with the human eye: out of 1017 photons aimed at the reflector, only one will be received back on Earth every few seconds, even under good conditions. They can be identified as originating from the laser because the laser is highly monochromatic. This is one of the most precise distance measurements ever made, and is equivalent in accuracy to determining the distance between Los Angeles and New York to 0.25 mm. As of 2002 work is progressing on increasing the accuracy of the Earth–Moon measurements to near millimeter accuracy, though the performance of the reflectors continues to degrade with age.

It's for the later problems that I assumed it was impossible without a mirror. However I'm the first one to admit I'm wrong it I am. But this is very odd. I contacted a friend of mine who's an astrophysicist at MIT and he found that to be very strange and also believed it wasn't possible. So if I'm wrong I'm in good company.

However I am certain that it's possible to use a laser to determine whether there is a that mirror on the moon simply by the flux of photons in the laser return.
Last edited by pmb on July 23rd, 2015, 4:16 am, edited 1 time in total.
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Re: Does Rocketry Work in the Vacuum?

Postby pmb on July 23rd, 2015, 4:01 am

Pilgrim wrote: No, M.I.T claimed they bounced a laser off the Moon in 1962, are you suggesting our esteemed pillars of American science were deceiving us back then?

It's people like you who make such horrible claims, not I. I was unaware of this experiment and I and another physicist I know never thought it possible. So I admit I made a mistake. You not being able to admit to your mistakes plus a lack of understanding of physics is what kept this thread going so long. Everything here is based on very poor understanding of science.

And since it was MIT Lincoln lab who was vital on imaging skylab its you who are claiming we're being deceived by them. MIT also did a hell of a lot of work on the Apollo missions. I personally know the man who was in charge of the Voyager Plasma Science Experiment during the Voyager Neptune Encounter. One of those spacecraft that you claim don't exist in space. One of MITs scientists was one of the Shuttle astronauts. Did he deceive you? See: https://en.wikipedia.org/wiki/Jeffrey_A._Hoffman
Jeffrey Alan Hoffman, Ph.D. (born November 2, 1944) is an American former NASA astronaut and currently a professor of aeronautics and astronautics at MIT.


Evidence of a friend of mine's theory was provided by the COBE satellite. Is that a lie too? I myself worked on the Chandra X-Ray space telescope that was launched back in the 1999. I suppose that was a lie as well?
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Re: Does Rocketry Work in the Vacuum?

Postby pov603 on July 23rd, 2015, 4:18 am

Working on something that you [and your co-workers] believe to be real isn't proof that it is real i.e. used for the purpose you believe it was intended.
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Re: Does Rocketry Work in the Vacuum?

Postby hoi.polloi on July 23rd, 2015, 5:12 am

I myself worked on the Chandra X-Ray space telescope that was launched back in the 1999. I suppose that was a lie as well?


What specifically did you do?
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Relativity Expert

Postby hoi.polloi on July 23rd, 2015, 5:29 am

By the way, since you have been writing about a number of different NASA topics, I have created this new thread that can be dedicated to the discussion.

As our latest member, and our resident "relativity" professional and/or expert (let's not be shy about the word since it's something you claim to be very good at), let's see what you can teach us. I am quite certain that the majority of all readers around the world would love to believe that someone who is very intelligent and who worked for a NASA project can teach us something about what they do, answer questions that they would know the answer to, and be able to respond clearly in their own words about it. We'd also like to assume that this person would be quite patient and professional in their manner and not act too "bent out of shape" if they received a hard question. Do you think that is a reasonable expectation? Do you think we can proceed without hearing from this intelligent professional that people who question them are inferior and/or do not deserve dignified and informed responses that demonstrate the extent of their personal knowledge and expertise?

Thanks for an understanding response. If you'd like to comment specifically about rocketry working in outer space, please feel free to actually address that topic (which I thought I read you writing that you would address) here: viewtopic.php?f=23&t=1632&start=525
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Re: Does Rocketry Work in the Vacuum?

Postby hoi.polloi on July 23rd, 2015, 5:48 am

HonestlyNow wrote:
pmb wrote:How did the mirrors that are on the moon that we bounce laser beams off of get there?

pmb wrote:As a physicist I know that such a thing is quite literally impossible. The laser beam would be so week after traveling only a mile that it'd be impossible to detect it after another 250,000 miles.

How do you reconcile these two statements?


I am also curious about your answer to this, pmb.
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