If you need assistance, please send an email to forum at 4hv dot org. To ensure your email is not marked as spam, please include the phrase "4hv help" in the subject line. You can also find assistance via IRC, at irc.shadowworld.net, room #hvcomm.
Support 4hv.org!
Donate:
4hv.org is hosted on a dedicated server. Unfortunately, this server costs and we rely on the help of site members to keep 4hv.org running. Please consider donating. We will place your name on the thanks list and you'll be helping to keep 4hv.org alive and free for everyone. Members whose names appear in red bold have donated recently. Green bold denotes those who have recently donated to keep the server carbon neutral.
Special Thanks To:
Aaron Holmes
Aaron Wheeler
Adam Horden
Alan Scrimgeour
Andre
Andrew Haynes
Anonymous000
asabase
Austin Weil
barney
Barry
Bert Hickman
Bill Kukowski
Blitzorn
Brandon Paradelas
Bruce Bowling
BubeeMike
Byong Park
Cesiumsponge
Chris F.
Chris Hooper
Corey Worthington
Derek Woodroffe
Dalus
Dan Strother
Daniel Davis
Daniel Uhrenholt
datasheetarchive
Dave Billington
Dave Marshall
David F.
Dennis Rogers
drelectrix
Dr. John Gudenas
Dr. Spark
E.TexasTesla
eastvoltresearch
Eirik Taylor
Erik Dyakov
Erlend^SE
Finn Hammer
Firebug24k
GalliumMan
Gary Peterson
George Slade
GhostNull
Gordon Mcknight
Graham Armitage
Grant
GreySoul
Henry H
IamSmooth
In memory of Leo Powning
Jacob Cash
James Howells
James Pawson
Jeff Greenfield
Jeff Thomas
Jesse Frost
Jim Mitchell
jlr134
Joe Mastroianni
John Forcina
John Oberg
John Willcutt
Jon Newcomb
klugesmith
Leslie Wright
Lutz Hoffman
Mads Barnkob
Martin King
Mats Karlsson
Matt Gibson
Matthew Guidry
mbd
Michael D'Angelo
Mikkel
mileswaldron
mister_rf
Neil Foster
Nick de Smith
Nick Soroka
nicklenorp
Nik
Norman Stanley
Patrick Coleman
Paul Brodie
Paul Jordan
Paul Montgomery
Ped
Peter Krogen
Peter Terren
PhilGood
Richard Feldman
Robert Bush
Royce Bailey
Scott Fusare
Scott Newman
smiffy
Stella
Steven Busic
Steve Conner
Steve Jones
Steve Ward
Sulaiman
Thomas Coyle
Thomas A. Wallace
Thomas W
Timo
Torch
Ulf Jonsson
vasil
Vaxian
vladi mazzilli
wastehl
Weston
William Kim
William N.
William Stehl
Wesley Venis
The aforementioned have contributed financially to the continuing triumph of 4hv.org. They are deserving of my most heartfelt thanks.
Registered Member #27
Joined: Fri Feb 03 2006, 02:20AM
Location: Hyperborea
Posts: 2058
That depends on your definition, you can't just take any signal and make it go faster than light. The signal will be reshaped and some information will move ahead. So even if something is moving faster then light the signal is not since it does not emerge at the other end in the same form or even with the same information content.
Something is moving faster than light but it does not seem like it is very useful for transferring normal information.
Registered Member #29
Joined: Fri Feb 03 2006, 09:00AM
Location: Hasselt, Belgium
Posts: 500
<*SIGH*> Why do these bogus "inventions" keep popping up? This is a classic problem that many students of electrodynamics will have seen..
OK..thought experiment:
1. radiation pressure on large end wall from wave bouncing off... 2. it can be shown that the radiation pressure of the smaller end wall does not exactly balance the force on the large wall... What's going on??? 3. Something is missing: the force on the "flared" side walls must also be taken into account. The algebra is messy, but using the WKB approximation if the cavity is long and thin, you can show this to first order. 4. Otherwise, use a computer EM solver and integrate the radiation pressure on all walls... It should cancel out.
In fact, integrating the poynting vector over a closed surface is equivalent to computing the integral of the radiation pressure (by a constant factor, c) If no net power flow across the surface occurs (because the surface is closed in a metal cavity), there is no transfer of momentum...and hence no net force!
In short, the article is bogus.... If the "physicist" who proposed this had studied harder in his EM clas, he would have moved on to a more fruitful project...
BTW- the site linked is not "New Scientist", but something called "EUREKA" or "free republic" It looks like one of those <*AHEM*> right-wing sites that is obviously known for its scientific rigor....
Registered Member #30
Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706
I don't believe it works personally, for the same reason as WideRaver gave. For an engine to do anything useful, power has to come out of the engine and go into the surroundings (as a spinning shaft, jet of hot gas, or whatever) but this thing just traps the power inside its cavity until it dissipates as losses. Unless power can get out of odd shaped cavities by a mechanism we don't know about, but I think if that were the case, the guys who make klystrons and atomic clocks would have noticed a while ago.
But it looks like the kind of thing any kid with a junked microwave oven could build and dangle from a counterweighted stick thingie to see if it moves when turned on. You wouldn't even need to do any metalwork beyond battering the oven cavity into a wedge shape with a big mallet Why don't one of you guys try it?
Registered Member #29
Joined: Fri Feb 03 2006, 09:00AM
Location: Hasselt, Belgium
Posts: 500
This is pure pseudoscience, in my opinion. Radiation pressure, besides being a very small effect, if there is no "exhaust" there will be no time-averaged thrust. (Here, it may be useful to think of water sloshing around in a tank... the tank may shake back-and-forth a little, but it really does not go anywhere...)
I will not be investing my retirement fund with these characters....
Registered Member #89
Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145
I agree with waverider; it can be imagined that uwaves are going to be much less dense at wide, flat side of the cone than on it's smaller end, effectively cancelling the forces out.
For more, the mentioned device seems to simply ignore newton's third law, wich leads to some bigger problems.
Imagine our motor (with some power source) powering itself up adn accelerating away from etc. earth, using some energy for this. When we want to stop it we can turn it on in opposite direction until it stops (or even return it to starting location and then stop if we wish)
Where did the used energy go?
Such device also ignores conservation of energy making it even more impossible.
In chemical or etc. reactive drives, when we slow something down we surrender the kinetic energy of our probe together with energy used by motor to exhaust gases of the motor.
In case we use electromagnetic reactive drive, vehicle's energy is surrendered by increasing radiation's frequency via doppler effect.
Registered Member #49
Joined: Thu Feb 09 2006, 04:05AM
Location: Bigass Pile of Penguins
Posts: 362
I agree with waverider; it can be imagined that uwaves are going to be much less dense at wide, flat side of the cone than on it's smaller end, effectively cancelling the forces out.
thats not what he said. the forces on the end cap alone in fact does not cancel out, which is what has tricked the inventor and the public. Only when you include the effectice area of the sloping walls does physics as we know it return to normal.
and I was tempted to say this is was a conservation of energy violator, but thought that might be going a little far. it is possible there exists a 'maximum Q' thats limited in proportion to the acceleration of the device and the power input, which might 'save' energy conservation.
This site is powered by e107, which is released under the GNU GPL License. All work on this site, except where otherwise noted, is licensed under a Creative Commons Attribution-ShareAlike 2.5 License. By submitting any information to this site, you agree that anything submitted will be so licensed. Please read our Disclaimer and Policies page for information on your rights and responsibilities regarding this site.
Emdrive (electromagnetic microwave reactionless drive) ?
Why don't one of you guys try it?
)
