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The 'impossible' EmDrive could reach Pluto in 18 months?

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Re: The 'impossible' EmDrive could reach Pluto in 18 months?

#81

Post by leni536 »

nickff wrote: post #59
thaumaturgy wrote: post #56

Earlier quoted context omitted.

Oh! This is one of my favorite questions about scientific progress. People seem to regard scientific progress as this kind of wave function, where some theory comes along and then some other theory or discovery disproves the previous one and so on and so forth. But if you want to think of scientific progress that way, then you have to think of it as a dampened sine wave ( https://en.wikipedia.org/wiki/Damped_sine_wav…

I'm sorry, but your reasoning completely escapes me. The only things that are left are very big, and very small? In addition to this being an incredibly vague catchall (which misses all the possible discoveries of 'black swans', that is phenomena and occurrences we have never seen), your statement more importantly misses the fact that humans don't even understand what something as common and important as light (or el…

> We've certainly characterized light's behavior (to some degree), though we still have basically no understanding of what it actually is.

As a physicist I really can't imagine what answer would satisfy you and could be falsifiable the same time. It is what it is, all we can do is to characterize its behavior.

Re: The 'impossible' EmDrive could reach Pluto in 18 months?

#82

Post by avian »

nickff wrote: post #59
thaumaturgy wrote: post #56

Earlier quoted context omitted.

Oh! This is one of my favorite questions about scientific progress. People seem to regard scientific progress as this kind of wave function, where some theory comes along and then some other theory or discovery disproves the previous one and so on and so forth. But if you want to think of scientific progress that way, then you have to think of it as a dampened sine wave ( https://en.wikipedia.org/wiki/Damped_sine_wav…

I'm sorry, but your reasoning completely escapes me. The only things that are left are very big, and very small? In addition to this being an incredibly vague catchall (which misses all the possible discoveries of 'black swans', that is phenomena and occurrences we have never seen), your statement more importantly misses the fact that humans don't even understand what something as common and important as light (or el…

> we still have basically no understanding of what [light] actually is.

Finding the true nature and, whether it exists or not, is the domain of philosophy.

Science builds models. And we do have at this point extremely good models of electromagnetism which can correctly predict results of all experiments done so far.

Whether these models reveal some fundamental truth or not is a matter of opinion (or perhaps religion). It has nothing to do with refining the models or finding experiments that might prove them wrong.

Re: The 'impossible' EmDrive could reach Pluto in 18 months?

#83

Post by nickff »

leni536 wrote: post #81
nickff wrote: post #59

Earlier quoted context omitted.

I'm sorry, but your reasoning completely escapes me. The only things that are left are very big, and very small? In addition to this being an incredibly vague catchall (which misses all the possible discoveries of 'black swans', that is phenomena and occurrences we have never seen), your statement more importantly misses the fact that humans don't even understand what something as common and important as light (or el…

> We've certainly characterized light's behavior (to some degree), though we still have basically no understanding of what it actually is. As a physicist I really can't imagine what answer would satisfy you and could be falsifiable the same time. It is what it is, all we can do is to characterize its behavior.

One could say the same of a stone, a plant, a planet, or a star, yet we do not simply characterize any of these, we endeavor to understand its origins and constituent parts. In the case of the star, we could have analysed its spectrum, size, trajectory (through space), and surface characteristics, then called it a day; yet we continually try to understand the elements which make up the star, what their state of matter is, how they are reacting, and many other aspects of the star. I disagree with you when you say (of light) that "all we can do is to characterize its behavior".

Re: The 'impossible' EmDrive could reach Pluto in 18 months?

#84

Post by XorNot »

rndn wrote: post #68
idlewords wrote: post #9

Earlier quoted context omitted.

From the abstract: "We identified the magnetic interaction of the power feeding lines going to and from the liquid metal contacts as the most important possible side-effect that is not characterized yet. Our test campaign cannot confirm or refute the claims of the EMDrive..." Given that this is a 700W microwave oven putting out a tiny amount of thrust, and that a positive finding would invalidate a basic conservation…

On the other hand, the current theory of the EmDrive predicted exactly that amount of thrust for the given configuration.

The current theory of the EMDrive is complete, absolute bunk. Whatever an EMDrive is doing, can in no way be described by the incorrect relativistic reasoning used by Shawyer.

Re: The 'impossible' EmDrive could reach Pluto in 18 months?

#85

Post by nickff »

avian wrote: post #82
nickff wrote: post #59

Earlier quoted context omitted.

I'm sorry, but your reasoning completely escapes me. The only things that are left are very big, and very small? In addition to this being an incredibly vague catchall (which misses all the possible discoveries of 'black swans', that is phenomena and occurrences we have never seen), your statement more importantly misses the fact that humans don't even understand what something as common and important as light (or el…

> we still have basically no understanding of what [light] actually is. Finding the true nature and, whether it exists or not, is the domain of philosophy. Science builds models. And we do have at this point extremely good models of electromagnetism which can correctly predict results of all experiments done so far. Whether these models reveal some fundamental truth or not is a matter of opinion (or perhaps religion)…

I think you misunderstand my point. Model-building is only one aspect of science, and happens to be the most prevalent in some (though not all) of today's mathematical and statistical based studies of physics (which are often criticized as an exercise in curve-fitting). One example is how string theorists are making a valiant (though perhaps errant) effort to understand matter; they are not simply modelling well characterized behaviors. There are many physicists and other scientists who are continually trying to understand their subject matter (pun intentional) at a deeper level, such as those who discovered and described DNA.

I am not interested in whether these scientists reveal "some fundamental truth or not", but we cannot say that we understand all there is to know about electromagnetic phenomena because we can make a few simple predictions. It would be tantamount to saying that we understand the sun because we know where it is relative to us, and how bright it is, and can predict both of these parameters for a while. Understanding that it is a star, how it was formed, how it will cease to be, that it is made up of a number of elements, and converts large amounts of matter to energy are all very important discoveries, and we must continue to seek this kind of advance in the frontiers of our understanding in electromagnetic phenomena, matter, gravity, and many other areas.

Re: The 'impossible' EmDrive could reach Pluto in 18 months?

#86

Post by leni536 »

nickff wrote: post #83
leni536 wrote: post #81

Earlier quoted context omitted.

> We've certainly characterized light's behavior (to some degree), though we still have basically no understanding of what it actually is. As a physicist I really can't imagine what answer would satisfy you and could be falsifiable the same time. It is what it is, all we can do is to characterize its behavior.

One could say the same of a stone, a plant, a planet, or a star, yet we do not simply characterize any of these, we endeavor to understand its origins and constituent parts. In the case of the star, we could have analysed its spectrum, size, trajectory (through space), and surface characteristics, then called it a day; yet we continually try to understand the elements which make up the star, what their state of matte…

Well maybe that's not all we can do. Maybe the abstraction of treating light and the rest of the Universe somewhat separately will break (of course we describe the coupling too). Maybe the abstraction of treating light as a non-dividable entity in the Universe will break. It would only create other axioms and/or other non-dividable entities, at what point would you be satisfied? It could very well be that you can't divide light any further and I would be satisfied with it if we can describe its behavior fully. If one says that light is a broken abstraction and you can describe the Universe using only "string" then you would ask "Yeah, but what strings are?".

I'm not saying that asking what light is is not an important question. But there is a possibility that there is simply no answer and yet we can have fully working physics. At least nobody will question your theories just because you don't tell what exactly your elementary particles are. They are elementary, we just have them, maybe light is not one of them.

Re: The 'impossible' EmDrive could reach Pluto in 18 months?

#87

Post by nickff »

leni536 wrote: post #86
nickff wrote: post #83

Earlier quoted context omitted.

One could say the same of a stone, a plant, a planet, or a star, yet we do not simply characterize any of these, we endeavor to understand its origins and constituent parts. In the case of the star, we could have analysed its spectrum, size, trajectory (through space), and surface characteristics, then called it a day; yet we continually try to understand the elements which make up the star, what their state of matte…

Well maybe that's not all we can do. Maybe the abstraction of treating light and the rest of the Universe somewhat separately will break (of course we describe the coupling too). Maybe the abstraction of treating light as a non-dividable entity in the Universe will break. It would only create other axioms and/or other non-dividable entities, at what point would you be satisfied? It could very well be that you can't d…

I think that your last point gets to the heart of the question, and you are right that we may never achieve a deeper understanding of light, matter, or gravity; but that does not mean that a deeper understanding is not desirable, or that we should stop asking the questions. Further, we will never know for certain when we have reached the bounds of our capacity to understand, so I will continue to ask "Yeah, but what strings are?". I always like to keep in mind that 'atom' means 'indivisible' in Greek, and yet we found that bound of knowledge to be surmountable (with debatable consequences).

I would also like to be clear that I am not criticizing anyone for making insufficient progress; it is just that there is a lot out there left for us to understand, and not all of it is marginal stuff that's "very big or very small".

Re: The 'impossible' EmDrive could reach Pluto in 18 months?

#88

Post by nickff »

leni536 wrote: post #80
nickff wrote: post #51

Earlier quoted context omitted.

Photoelectric cells were invented before we understood the photoelectric effect, alcohol and preserves were used to store drinks and foodstuffs before we understood microbes, forging and annealing used before anyone had a theory on metallic crystal formation, and incandescence was used before anyone understood electromagnetic radiation; to name but a few examples. Why would it be surprising that someone invented a de…

Inventing a device which is not well understood and inventing a device which contradicts things that are thought to be well understood are two different things. The photoelectric effect was pretty big news though and it did break existing laws that time so it doesn't really fit here.

I could argue that all the inventions I mentioned violated one existing theory or another at the time of their creation, though the level of scientific reasoning behind each is different. Remember that at one time, many believed that heat was an element released from logs by fire, which is a theory clearly violated by the incandescent light bulb, and other earlier examples of incandescence (such as that of other heated metals).

Regardless, how is it relevant whether a large group of people made a mistake (by coming up with an incorrect theory) before an invention that had no basis in existing theory was made? I do not agree with the premise of the post I responded to, as a new drive does not necessarily contravene existing theories (since we do not understand its principle of operation).

I agree that contravening an existing theory is a bit of an odd course for an inventor to take, and may make it difficult to get angel funding, but that's about the only difference I can see.

Re: The 'impossible' EmDrive could reach Pluto in 18 months?

#89

Post by aroberge »

gizmo686 wrote: post #23
yincrash wrote: post #18

Earlier quoted context omitted.

Can anyone explain electromagnetic momentum? I thought that em waves (photons) are massless. How can they have momentum (mass * velocity)?

Because photons travel at the speed of light, we need to consider relativistic effects. Under special relativity, classical momentum (mass * velocity) is not actually conserved. To achieve conservation of mass, we consider the "inertial mass" of an object instead of the classical mass, where the intertial mass is given by: m'=ym y=1/sqrt(1-(v/c)^2) As you can see, y>1 and y approaches infinity as you speed approaches…

"Relativistic Inertial mass" (m' = ym) is a bogus term invented so as to make the equations look the same as the classical ones in some limited circumstances - namely, when a force is acting in the same direction as the relative velocity. If a force is acting in a different direction, to obtain a relation of the form F=mdp/dt, you need a different* so-called relativistic inertial mass.

I know of no one doing modern research in relativity using this obsolete concept.

Re: The 'impossible' EmDrive could reach Pluto in 18 months?

#90

Post by thaumaturgy »

nickff wrote: post #85
avian wrote: post #82

Earlier quoted context omitted.

> we still have basically no understanding of what [light] actually is. Finding the true nature and, whether it exists or not, is the domain of philosophy. Science builds models. And we do have at this point extremely good models of electromagnetism which can correctly predict results of all experiments done so far. Whether these models reveal some fundamental truth or not is a matter of opinion (or perhaps religion)…

I think you misunderstand my point. Model-building is only one aspect of science, and happens to be the most prevalent in some (though not all) of today's mathematical and statistical based studies of physics (which are often criticized as an exercise in curve-fitting). One example is how string theorists are making a valiant (though perhaps errant) effort to understand matter; they are not simply modelling well char…

So, I originally argued the point that progress in the physical sciences generally doesn't involve utterly canceling out previous discoveries. The link to Asimov's article elsethread illustrates this better than I could hope to. Relativity for instance did not find that Newtonian mechanics was wrong, it simply revised it under pathological cases. The Bohr model of the atom isn't completely wrong, and it's still useful in chemistry, it's just that as physicists have learned more they've found details where it's not completely right either. This kind of constant revision is a theme throughout the history of scientific progress.

So that leaves me a little bit stumped at what point you're trying to make here. Are you disagreeing with that view of science? Are you trying to say, "well, that's how it's been for hundreds of years, but at some point in the future I believe we'll all discover that physics is completely and utterly and embarrassingly wrong in every way"?

I've gone back and reread your reply to me at least half a dozen times. You seem to be disagreeing with me, but none of the examples you brought up really actually disagreed with me. At best, I chose some poor metaphors and that led you to misunderstand me, but then I still can't figure out what it is that you're actually trying to say.

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