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deltaH
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Propulsion
Why do all forms of propulsion require mass be expelled out in the opposite direction in some way, shape or form, i.e. why can't energy be converted
into a force directly?
I'm well aware of Newton's Laws, I'm trying to understand why those laws exist fundamentally... specifically why the need for mass to be involved.
[Edited on 10-1-2015 by deltaH]
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deltaH
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Yes... but that still involves movement of mass. Even light has mass. In my original post I used the word matter, but corrected this, maybe you posted
this after reading my original?
What I'm really trying to understand is why one can't have a sci-fi like 'engine' that you power with electricity and it creates a force without
firing something with mass backwards.
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Bert
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Sorry, screwed up and deleted while editing-
--------
You've seen these?
 
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Bert
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I am way too out of touch with my inner Jules Verne. Sorry...
Can you move information without moving mass?
[Edited on 10-1-2015 by Bert]
Rapopart’s Rules for critical commentary:
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deltaH
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Post above still stands as a reply to this. What's this first photo you added? I don't recognise it.
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deltaH
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Quote: Originally posted by Bert  | I am way too out of touch with my in inner Jules Verne. Sorry...
Can you move information without moving mass? |
You've lost me. What do you mean?
This does, however, remind me of Maxwell's Demon which could only be explained when it was realised that information was neg-entropy. That totally
blew my mind as an undergrad!
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Bert
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It's the Japanese IKAROS light sail spacecraft.
http://en.m.wikipedia.org/wiki/IKAROS
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deltaH
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Yes but light has mass and this mass impacts causing a force... I'm talking about massless interaction causing a force. Some closed electrical device
that power's up and gives a push in space, for example.
OK, shining a light out of a spacecraft would give a very small push, granted, and that would be converting electricity into a push, but that force is
minute. In any event, shining a light out would not technically be completely a closed system, anyhow. But the bottom line is that if you 'throw out'
a little matter mass powered by the same energy source and the force is orders-of-magnitude larger... again why?
[Edited on 10-1-2015 by deltaH]
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aga
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Light behaves as Particle as well as Wave.
A super-powerful Laser will push a 'sail'.
It shouldn't, but there it is.
Basically we don't understand it very well at all - yet.
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deltaH
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Yes exactly, because light has mass, but why can we not do it massless. Why this property of our universe that only mass can move mass. I mean energy
can do work, so why can energy not move mass without having to eject mass (even if it is light).
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Bert
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Propelling a mass magnetically as in a rail gun? Not too practical, but does it meet your requirement?
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HgDinis25
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Imagine that you have a small toy with an electromagnet. You have a regular magnet rigth next to the car. When you turn on the electromagnet (North
pole must be facing North pole or South pole must be facing Southe pole) the toy car will move away. You just gave that car a massless (is this even a
word?) push.
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phlogiston
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No, the magnet is pushed in the other direction. If the magnet was attached a very massive object such as the earth, the change in momentum of the
earth will be too tiny to notice but nevertheless there.
<b>There is no way to get around the law of momentum conservation</b>, if that is what you are after.
Regardless of what you choose to propel yourself with (light or matter), the total momentum in the system remains the same.
[Edited on 10-1-2015 by phlogiston]
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"If a rocket goes up, who cares where it comes down, that's not my concern said Wernher von Braun" - Tom Lehrer |
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deltaH
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@Bert, no I meant something that works in space as a kind of engine. Terrestrial things can push against the mass of the earth, again a mass effect...
@HgDinis25, your pushing against something that has mass, which is why it works... if you did that in space then both you and the car would move apart
right? So in a way, you become the mass ejected to cause the car to move.
There is this, but isn't this pseudoscience?
[Edited on 10-1-2015 by deltaH]
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phlogiston
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Disregard all the 'electrogravity' stuff which is definitely pseudoscience.
Ion propulsion is well known and has even been used in spacecraft.
Again, it does not violate the conservation of momentum. It just works by propelling ions to very high speeds in an electric field. The advantage is
that because of the high speed you only need very little mass to get an appreciable force. For spacecraft, this is desirable because you only need to
launch a very small mass of fuel (saving cost) which you then accelerate using energy that you can get from a solar panel, nuclear reactor, etc.
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"If a rocket goes up, who cares where it comes down, that's not my concern said Wernher von Braun" - Tom Lehrer |
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Bert
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The only thing that moves in a fashion that meets your criteria is bad news!
Rapopart’s Rules for critical commentary:
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Anatol Rapoport was a Russian-born American mathematical psychologist (1911-2007).
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Little_Ghost_again
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I like the idea of dark matter, or anti matter. I tried reading some quantum mechanics out of interest but it truly messes with your head when you see
the wavy line experiment with a photon of light.
Then you have the idea of black holes and how they behave.....................But in the end you still cant get more out than you put in.
Dont ask me, I only know enough to be dangerous
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deltaH
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@Phlogiston, my impression as well. Ion rockets are very promising, I even built an electric wind rotor as a science project when I was a child
drawing inspiration from them.
But all of this digresses from the main point, this thread is less about finding an alternative than understanding the link between mass and force,
that was more what I was after.
Like I said when I started the thread... the link between mass and force is an inescapable certainty (unfortunately), but how does it work
exactly or why this special relationship with mass.
In my mind I was toying with E=mc^2 thinking that in principle, energy can have a mass effect, but it would be c^2 times less effective, but again,
doesn't explain why mass is so good at making force.
Are there 'force particles' that are associated with mass?
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j_sum1
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There are basically two ways of quantifying a force. One is by comparing it to.a known force, which, in this context is not useful. The other is by
causing a mass to accelerate.
In ither words, the very concept of a force is intractibly linked to mass. It is in the very definition. And summarised nicely in the formula F=ma.
So your question falls over at a fundamental level. It is very much like asking why 3 is the number after 2. No reason except that thats's what we
call it. A force is that thing that causes masses to accelerate.
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deltaH
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@j_sum1, are you satisfied with just accepting the result, no curiosity as to the why or more specifically, by what 'mechanism' does force
cause masses to accelerate?
This is such a fundamental and common effect that I'm stunned not to hear an explanation for how it works. Comparing to chemical reactions, mechanisms
are extremely important and heavily studied, so what is the mechanism here?
F=m.a is a result or phenomenological observation, as I see it, but how does it arise?
But at least the question is getting better refined... maybe I'm wasn't wording it correctly.
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j_sum1
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No. F=ma is a statement of definition useful for describing observable phenomena.
If you could find a force that fits your criteria, then it would not be a force.
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franklyn
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http://www.youtube.com/watch?v=FxRdNj0_8JU
Maxwell mused that energy might be continuosly created and destroyed at very small scales but we only observe the average which is zero. This later
was posited as the Dirac field, evolving into what today is accepted and known as quantum foam or the zero point field. At very small scales of time
and space, the Heisenberg uncertainty principle allows energy to condense to create virtual particle antiparticle pairs which mutually annihilate
without violating physical conservation laws. The smaller the scale of time and space , the more the virtual particle's energy increases.
" Quantum vacuum virtual plasma ", I expect uses particle pairs that continually appear at the zero point level quantum foam, and during their brief
existence are made real by the infusion of energy to augment their mass. This created mass having inertia can thereby be acted against to propel a
vehicle by classical force reaction. Small amounts would be sufficient providing the coupling of force to it is large and efficient.
Anomalous Thrust Production from an RF Test Device Measured on a Low-Thrust Torsion Pendulum , Brady, White, March, Lawrence, Davies
http://www.libertariannews.org/wp-content/uploads/2014/07/AnomalousThrustProductionFromanRFTestDevice-BradyEtAl.pdf
http://nextbigfuture.com/2014/08/full-nasa-cannae-drive-and-...
@ deltaH
" Why do all forms of propulsion require mass be expelled out in the opposite direction in some way "
That's a poor assumption , Newton's laws doesn't state that. http://www.grc.nasa.gov/WWW/k-12/airplane/newton.html
Anyway perhaps not all , though this remains to be seen.
http://www.sciencemadness.org/talk/viewthread.php?tid=1970&a...
http://www.sciencemadness.org/talk/viewthread.php?tid=6069#p...
Read 4th paragraph down here _
http://www.sciencemadness.org/talk/viewthread.php?tid=22493#...
Rigorous quantitative test of Biot-Savart-Lorentz forces
Journal of Applied Physics of the American Institute of Physics ,
Electromagnetism as a second order effect
Department of Physics & Astronomy , State University of Iowa
http://www.sciencemadness.org/talk/files.php?pid=267280&...
@ phlogiston
" Disregard all the 'electrogravity' stuff which is definitely pseudoscience."
If we knew what it was we were doing, it would not be called research , would it?
— Albert Einstein
Whoever undertakes to set himself up as a judge of Truth and Knowledge is shipwrecked by the laughter of the gods.
— Albert Einstein
.
[Edited on 11-1-2015 by franklyn]
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Molecular Manipulations
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I'm a little confused by your question.
So you want a closed system which moves mass (the rocket) without ejecting mass and without touching any other mass to get traction? An electric
machine that generates an untangable thrust force from electrons flowing from one place to another.
I don't know why it doesn't work, but I can't think of a way it could.
If a way was found, think of the nuclear rockets!
I know this isn't really related, but could an antimatter rocket work?
Matter colides with antimatter and forms gamma rays, which shoot out and cause thrust.
-The manipulator
We are all here on earth to help others; what on earth the others are here for I don't know. -W. H. Auden
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deltaH
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@Franklin
Fascinating point, I'll have a read into this a little later, thanks for the contribution.
@Molecular Manipulations
Well the question was more as to the why, not the alternatives, but ok, I give up, it seems the alternatives are just too interesting to everybody
 Just don't flame please if this conversation goes down that road.
The matter-antimatter annihilation sounds interesting... problem is that I don't see us farming usable amount of antimatter in our lifetime...
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ElizabethGreene
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I's like to understand this as well. My understanding is that it doesn't necessarily. The EmDrive and Woodward effect both seem very promising in
disproving this motion requires mass assertion.
Warning: This is experimental edge science and publications on it get attacked with a cold-fusion like near-religious fervor.
Mentally I've generalized these devices to "a resonant or oscillating system where energy is added or removed in an asymmetrical manner." I'm curious
if this generalization is a correct and I'm building a mechanical device to test it.* I'd designed it and cut most of the parts before someone said
"oh, like a dean drive", whereupon I immediately looked it up and said some profanity. I strongly suspect it will not work now.
* (What is the diameter of a round 'tuit?)
Lacking access to a ballistic pendulum, I propose the following earth-test protocol for a "reaction-less thruster". I would appreciate very much it
if anyone would point out flaws and poke holes in this for me. I propose to Encase the device in a steel box (a metal cash box) to eliminate magnetic
field effects, encase that in a sealed plastic bag to eliminate gas releases, encase that in a non-conductive foam box to preventing obvious thermal
and Ion effects and suspend that from a string. Tinsel, streamers, or bits of string will be around the box, string, about the room, to visually
indicate any external air current interactions. A successful test would consist of making the object move significantly, (not just oscillate in place
like a vibrating pager motor)
Does that seem reasonable?
Thanks,
Ellie
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