Greatest Achievement in Engineering 8

[zdas04]

There was recently a thread in another forum from a student asking for opinions on "What is the Greatest Achievement in Engineering" of all time. The thread in that forum violated several of eng-tips rules and was inappropriate. But it got me thinking what really was the greatest engineering achievement of all time? Was it one of the early efforts of developing the wheel or the lever? Was it the U.S. space program that spun off so many wonderful new technologies? Was it the computer? Was it the aqueduct's of Rome?

What is your perspective on the greatest achievement in engineering of all time? All answers must be justified and defended there is no "right" answer, but I hope there will be many "wrong" answers.

David

 

[25362]

Don't forget paper making.

 

[EddyC]

A Civil Engineering colleague of mine said that clean water supply systems and sewage systems have saved more lives than anything else, by preventing disease.

 

[EnglishMuffin]

flame: Depending on how you define them, science and engineering do not have to be inseparably intertwined. But for the purposes of this discussion, it is only necessary that they be defined, either as one and the same or not, otherwise the answers cannot be compared since they are all responses to different questions. Of course, I suppose you could argue that we are not taking a poll, and everyone is being careful not to come up with the same answer anyone else has, in which case it doesn't really matter, but this might seem a rather vacuous exercise to some.
In regard to "Newton's" laws of motion, the first and most of the second are due to Galileo. I am not sure whether anyone else anticipated the third - I'd be interested to know. And in the form that they appear in nearly every textbook today, they are somewhat illogical, since the first is simply a corollary of the second. An important adjunct of Newton's to the second law relating to the parallelogram of forces is also completely omitted. I have only ever come across one advanced textbook which attempts to correct these deficiencies. Since the laws have achieved almost religious significance, the attempt was obviously doomed to failure, although you cannot argue that the usual elementary textbook forms are fathful to Newton either, since they usually make no mention of momentum. I do think Newton must be credited with the remarkable insight that everything in mechanics could be explained with just these laws, and that there weren't any more. To me, that is his great achievemnet, rather than the laws themselves.

 

[25362]

When speaking of the laws of motion, Aristotle, Galileo, Newton and Einstein should each be considered as laying a step in the rising stairs of knowledge.

Galileo and Newton both showed that the Aristotelian commonsense observation that rest is the natural state for objects on Earth was wrong, and (philosophically) shifted towards uniform motion as a natural state of things. It was Newton -when studying motion- who, with his first law, emphasized not the cause of motion but the cause of changes of motion.

This cause is the net force, F (i.e., the sum of all forces acting on a body) quantified in Newton's second law of motion by equalling it to the rate of change of the body's momentum p (velocity v multiplied by mass m). As long as the body's mass doesn't change, the law can be written:

F = dp/dt = d(mv)/dt = m dv/dt = ma​

Any change in the velocity vector -either in magnitude or direction or both- represents an acceleration (a).

Newton's third law of motion states that forces always come in action-reaction pairs. The second and third laws together permit a consistent description of the motions of interacting objects.

It was Galileo's idea of inertia that resulted in what is called the principle of Galilean relativity, which states that the laws of mechanics are valid in all frames of reference in uniform motion. Its ultimate meaning being that there is no way of using the laws of motion to answer the question "am I moving?", since with respect to the laws of motion, the question is meaningless; only relative motion matters.

Einstein showed that our commonsense notions of space and time are not quite right, and in the process he was able to extend the principle of Galilean relativity to all of physics in his special theory of relativity.

As a result all equations of motion (including those of Newton) are really only approximately correct; they work well for our everyday experience, and even for spacecraft probing the solar system, but they break down when relative speeds approach the speed of light.

 

[zdas04]

25362,
So to get back to Dave's framework, would you give Newton a 10 on Impact and 10 on Reverberation?

David

David Simpson, PE
MuleShoe Engineering

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[25362]

I believe it would be reasonable to give Newton a 20 (=10+10) using Dave's scale.

 

[EnglishMuffin]

zdas04: I think a more interesting question is what would you award Einstein? And are we in any case awarding the individual with an achievement rating or are we evaluating the theory with which they are associated, but are not necessarily fully responsible for ?
25362: (1) As far as I am aware, nobody to date has ever shown that "Newton's" laws are anything other than 100% correct - although it depends on how one defines the "m" term. To make them consistent with Lorentzian or Einsteinian relativity it is merely necessary to replace the "m" in the second law with Mo/sqrt(1-v^2/c^2), where Mo is the rest mass. If one takes “m” to be the apparent mass as recorded by a stationary observer, they are 100% correct without modification, as far as is presently known.
(2) If one defines Newton’s second law in the form F = d(mv)/dt with no further qualification, then Newton's first law is simply a special case of this with F=0 (see Synge & Griffith – Principles of Mechanics, 3rd Ed). If the second law is expressed in this modern algebraic fashion with no further qualification, as in most textbooks, there is no reason to suppose that the case "F=0" is excluded from the second law. Newton, however, used Latin, and considered the case of F=0 separately from the non-zero case, perhaps in deference to Galileo. Incidentally, I have yet to see a convincing explanation of why the original English translation of Newton's second law makes no mention of a rate of change of momentum, but only a change of momentum. He also says that twice the force produces twice the momentum, which seems ambiguous to say the least, and would hardly get one full marks in a modern examination. Perhaps it is all the fault of the translators.

 

[EnglishMuffin]

Some further comments :
Only zdas04 can know exactly what he really had in mind when he posed the question “Greatest Achievement in Engineering”, and presumably we must defer to him in the event of any disagreement. He appears happy to include the whole of natural philosophy within the purview of the term “Engineering”- which I don’t agree with, but it’s his question and he can define it any way he wants. He also appears content if we take “Greatest Achievement” to mean “most important events”, or something of that sort, and Dave’s numerical formulation appears consistent with that, if we assume by “impact” he means “immediate impact” – otherwise it’s something of a tautology.
But personally, I prefer to interpret the question in what I take to be its literal sense, which to me is the more interesting question, although of course it is a far more controversial one. For instance, I consider the Wright brothers (et al) efforts up to 1909 to be one of the greatest engineering achievements of all time, not least because there were only two of them, plus al, (just kidding) and they were so methodical and scientific in their approach and worked extremely quickly. However, at the time, they had almost no impact (because they were so secretive) and few of the detailed contributions which were unique to them have stood the test of time, so I would give them a fairly low reverberation score also. If impact and reverberation alone are to be the yardstick, a la Dave, then to answer the original question honestly one would have to evaluate where we would be today if the Wrights had never been born – which is a very difficult and controversial exercise. Just how controversial can be gleaned from the following, for example:

http://www.thefirsttofly.hpg.ig.com.br/pioneer2.htm

. If on the other hand, one’s reply to the original question was “The development of flight”, that would undoubtedly have high impact and reverberation scores.

 

[zdas04]

EnglishMuffin,
I'll pass on the Einstein question because I am after all quite a coward.

I will take a shot at the second half of your question. I'm looking for the forum's opinion of the "Greatest Achievement in Engineering".

Many of the accomplishments that are attached to a specific name really represented things that previous work in many fields had made inevitable - and the person who got tagged with it just had the best PR. The best example of this was mentioned above with the "invention" of calculus. Most casul observers would say with certainty that Newton was the "inventor", but it doesn't take much research to put that "fact" into question.

As I said above, I think that the "winner" of this silly exercise (that I'm really enjoying by the way) will be some discovery/development/invention that brought about a "sea change". Personnaly, I don't care that Newton's "Laws" were mearly a re-hash, re-statement of previous work. What I'm interested in is the fact that codifying the description of the way that the universe works in response to a specific set of forces enabled the development of much of what we call "engineering" today. To use Dave's term, that is some "reverberation".

David

 

[EnglishMuffin]

Well, I don't think it's silly if it leads to some interesting discussions. I do think Newton's "Principia" is one of the biggies in science - the laws of motion were only a tiny part of this monumental work, which has to score big on impact and reverberation (and personal achievement) - it changed the whole mind-set of science. (It doesn't have much to say about calculus by the way). But as I said, I don't consider science to be engineering. Actually, Newton wasn't a bad engineer either - the reflecting telescope is one example. By some accounts, he started out as a kid making small mechanical models.

 

[25362]

To EnglishMuffin, I agree in that the laws of physics, among them the cornerstone "conservation of momentum", don't change in special relativity. However, I was taught decades ago as follows:

1. The relativity factor (gamma) you rightly mention is meant to correct the definition of momentum, not the rest mass. The right definition of momentum should be p=mv/sqrt(1-v²/c²). It is the increased momentum at high velocities (near the velocity of light "c") that makes the forces needed to change these velocities impossibly high.

2. Newton's second law expressed as p= mv would predict the momentum (as well as the force) to increase the velocity of a particle from rest to 0.01c, or from 0.98c to 0.99c, to be the same. The Newtonian expression would, incidentally, be sufficiently accurate at the low speed, but far off mark at the higher speeds.

3. The Newtonian expression for kinetic energy K=1/2 mv² bears little resemblance to the relativistic K=(gamma-1)mc². Only when v<<c can the latter be converted into the former expression. When adding the rest energy expressed by the popular equation E=mc² we get the total energy E_total=gamma.mc².

Would I be wrong all along?

 

[EnglishMuffin]

25362: This is all way off topic, but I did not say anything about "correcting" the rest mass - the rest mass in Newtonian physics is the same as the rest mass in Einsteinian relativity. The definition of momentum in Newtonian physics is exactly the same as in Einsteinian relativity and needs no correction. The only thing that changes is the interpretation of m. The following two quotes are verbatim from from Lectures in Physics by Feynman:

p15-1 : Newton's Second Law, which we have expressed by the equation F= d(mv)dt, was stated with the tacit assumption that m is a constant, but we now know that this is not true, and that the mass of a body increases with velocity. In Einstein's corrected formula m has the value
m = Mo/sqrt(1-v^2/c^2)

p15-9 : Momentum is still given by mv, but when we use the new m this becomes

p = m*v = Mo*v/sqrt(1-v^2/c^2)

End of quotes.
The only thing I am quibbling with here is Feynman's use of the word "corrected" on p15-1 - I think the word should simply be omitted. The "tacit assumption" mentioned by Feynman is his, not Newton's. The m in Newton's second law can actually be a fixed or variable quantity.

Actually, if you listen to the original CalTech recording of Feynman’s actual presentation of this lecture on relativity, he begins jokingly by saying that all you have to do is make the substitution m = Mo/sqrt(1-v^2/c^2), and then says “that’s it – end of lecture !”

The following quote is from "Einstein plus two" by Petr Beckmann:

"Let me take this opportunity to dispel another myth, namely that Einstein's theory contradicts Newton's laws. .....Newton never took the m out of the parenthesis in d(mv)/dt, for he was too careful a man to ignore the possibility that inertial mass might be variable. When Einstein introduced velocity dependent mass explicitly, he did not have to change one iota of Newton's laws of motion for any part of his theory; that he developed it in contradiction to them is one of the numerous fables surrounding the Einstein theory".

You may of course object that Petr Beckman was "merely" a professor of electrical engineering, but that does not prevent him from being right in this particular case, whatever you may think of his writings in general.

One of the problems with relativity is that a lot of it has become overlaid with metaphysics, which I think this demonstrates.

 

[25362]

Newton's second law indeed showed force F=dp/dt, nevertheless F=ma is a more widely recognized formula.

I wonder whether Newton had the insight to rightly believe that momentum p -not mass, m- is a physical fundamental property.

Newton's times were too early to know that mass can be reduced by releasing energy. One would have to wait until the 20th century and Einstein's relativity to start considering the mass-energy equivalence.

One more thing to put things in proportion. Newton's laws are laws of inertia. As such they don't apply on accelerating frames of reference. As when we try to throw a ball while standing on a whirling merry-go-round. We'd have trouble in getting it where we wanted. A merry-go-round is a rotating -and therefore accelerating- frame of reference and Newton's laws wouldn't hold.

Strictly speaking Earth's rotation makes it also a non-inertial (accelerating) frame of reference. Oceanographers and atmospheric scientists take this fact into account when studying the large-scale motions of oceans and the atmosphere.

It would be a slight exaggeration to say that F=ma covers all of classical physics, but it helps analyse a sky-scraper's response to gale-force winds, predict the position of planets and the timing of eclipses, and develop better tennis rackets. It lets us predict the motion of objects; as a result, for example, we can send a spacecraft to Jupiter, design new aircraft engines, or determine the safe distance between cars on a highway.

 

[EnglishMuffin]

Whether or not Newton had any particular insight, and the fact that Newtonian physics as a whole has been superceded, are both beside the point. I simply state that Newton's laws of motion are as valid post Einstein as they were before. It should also be pointed out that you can use F=d(mv)/dt for accelerating rocket calculations (where the rocket mass is continuously changing), as well as for Einsteinian mass change situations - so it is quite conceivable that he could have been thinking of such a thing. However, his definition of mass might leave something to be desired, since it has been criticized by some as being circular.

 

[xnuke]

I think the last few posts have gotten off the topic of the thread.

In my opinion, the greatest achievement in engineering was the conversion of what is essentially a paraphrasing of the scientific method into something that could directly affect systems without human intervention - automatic feedback. Of course, being a controls engineer, I'm a little biased toward my field.

In the scientific method, a physical phenomenon is observed, a hypothesis developed, it is tested empirically, and refinements are made to the hypothesis. This is an iterative process that uses feedback.

A control system senses a physical phemomenon (a change in the process variable), determines a required response mathematically/logically, and adjusts the system to cause it to exhibit a desired behavior. This is also an iterative process that uses feedback, and I think it parallels the scientific method fairly well.

There have been many examples throughout history of engineering successes and marvels, but my favorites are those in the field of controls. Many things are built so robust that they can stand up to disturbances (think buildings and wind gusts), but those that can automatically compensate for disturbances never cease to amaze me (think the automatic leveling of the Kansai airport terminal in response to its uneven sinking into the man-made island on which it sits).

Most of the technology today would have never been developed without the idea of feedback. The idea is used in many fields, not just those related to technical accomplishments. Movie studios screen their films to test audiences and make adjustments before releasing the final cut. Students fill out end-of-term critiques on their classes and professors. The Federal Reserve makes changes to interest rates to tweak the economy of the U.S. All are forms of using feedback to adjust a system, but control systems can do it all automatically.

xnuke

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[EnglishMuffin]

Let me be the first to agree with you - probably my fault. But sometimes the meanders in these threads are more interesting than the original question. At least we were still talking about history.

"....the greatest achievement in engineering was the conversion.... ". So when in your view did this conversion first occur? (just interested - I'm a little hazy about the history of the development of automatic controls).

 

[jmw]

I would guess that if I suggest the fly-ball governor as an example of automatic speed contro, i will get clobbered by some one with an automatic mechanism from way back when.

Same with flow measurement, for example. It's a fair bet that the water cultures depended on some form of flow measurements and indeed, in Ancient Egypt we have the Shaduf as one method for quantifying the amount of water removed from the Nile or irrigation channels by each cultivator (the Shaduf being a bucket on a counter-balanced pole) and we also have the "Nilometer" a graduated "stick" used in the nile rapids for open channel flow measurement. Not as sophisticated as today, I understand, because their math is not believed to have been up to the flow equations but good enough for empirical data use.

We will find this for most proposals i think, a difficulty isolating one product in a developmental sequence that probably goes back through the centuries and is interdependent on numerous other inventions.

Be nice to find something that stands out alone as a sudden an unexpected achievement that is evidently a leap of imagination. For pyramids we have them as the evoltionary achievement of all sorts of structures including the earlier mud pyramids. They didn't spring fully formed and perfect either, the first pyramids had a habit of slumping if the sides were too steep. Clearly an evolutionary learning curve.

JMW

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[25362]

As a corollary (I hope final) to EnglishMuffin thoughtful remarks on Newton's laws.

EM is right when treating mass as a variable as for a rocket ejecting fuel, or for a body approaching "relativistic" velocities (close to c). In my previous post I just referred to the interconversion of mass and energy.

The motion of rockets or satellites is indeed related to the fundamental physical principle of conservation of linear momentum that has been derived from those laws. When no external forces are applied, the second law tells us that F=dP/dt=0, thus P = constant.

The principle of conservation of linear momentum in a system of particles (using the concept of center of mass), is even more basic than Newton's laws in that it applies not only to rockets -or everyday subjects like hydraulics, sports, etc.- but extends even into the realm of subatomic and nuclear physics -as in radioactive decay, particle scattering, etc.- where the laws and even the language of Newtonian physics are hopelessly inadequate.

Coming back to the main issue in this thread Newton's laws are indeed a monumental achievement in mechanical physics, if only when looking at the extremely useful derivations humanity managed to develop from them.

 

[jmw]

I think that as tool of phenomenal power, the telescope is a candidate:

Hans Lippershey (c1570-c1619) of Holland is often credited with the invention, but he almost certainly was not the first to make one. Lippershey was, however, the first to make the new device widely known.

http://inventors.about.com/library/inventors/bltelescope.htm

Why? because it's a very powerful tool. As a reult of this beginning, other similar tools were developed that enable the universe to be examined throughout the electromagnetic spectrum.
This has had a profound impact in the fields of astronomy and cosmolgy.

It is only in recent years that we are make our first tentative steps to extend our physical reach to the nearest planets.

Engineers are, by and large, touchy feely folk. The tangible artifact is something that can be deconstructed, evaluated, measured, re-constructed and thoroughly understood directly through our senses.

But it is the ability to discover so much about the universe simpley by looking through a bit of glass is amazing.



JMW

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[patprimmer]

After further studying the mood and direction of this thread, I am now convinced the answer is 42

Regards
pat pprimmer@acay.com.au
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