Nov
6th
2019
Conservation of Momentum · 8:22pm Nov 6th, 2019
Nice article debunking the 'Helical Drive' - an idea for spacecraft propulsion without propellant that has been propelled a bit more than it deserves to be on social media.
Near-infinite specific thrust from drive that ignores physics
Illustrated with a picture of a unicorn? Can't help but think this particular type of non-conservation of momentum is rather more Pinkie Pie's style... Or perhaps Scootaloo...
With an interesting insight into how things work in NASA:
...the author's job title includes the word "manager," so the more time he spends on this, the less damage he can do managing.
The thing I got from the article was the 163 Megawatts per Newton, or fracional newton thrust?.. That is, the non zero value was at least in the error range in the measured speed of light.
If you are going to use an asymetrical design, I propose a model, that is blatent in its abuse, so it can be easily demonstrated why it cannot work, and so can be demonstrated as a variation for as many other similar designs as possible.
I call it the Ping Pong drive.
Model it using two accelerators, a cyclotron, or cavity magnetron, and a linear accelerator, or a CRT electron gun.
Demonstrate that for a given energy momentum, the total sum around half the circular motion at constant relativistic speed, equals twice the linear sum of taking the relativistic beam to zero then reaccelerating it back in return. You can distract lots of people with trying to use quantum spaced barriers to contain the brehmstrallung and recycle energy etc.
Personally Id got for a Hafnium OxyGraphide solar sail, dropped almost into the sun, approx top speed out of the solar system. 20%c Very rough estimation.
Another one Id lovee to try is the Paperclip Wave Ride.
Why cant asymetrical drives pushe against space time and so use the universe as reaction mass? Thre has to be a difference somewhere, otherwise we couldnt measure gravity?
I have to agree. If you're literally working at NASA, then between "wouldn't it be cool if..." and making the PowerPoint, there should be a step where you ask someone who knows if the idea can actually, you know, work.
That said, I think we've found something for the Equestria Space Administration to look into. Even if the "jumping bean in a can" model does seem more up Pinkie's avenue.
Tangentially Relevant XKCD Is Tangentially Relevant.
See also: EmDrive
I frequently cringe when I see titles of science articles. "Neutrinos travel faster than light!" No. No, they do not.
5151450
Picking at somepony for using scientific terminology inaccurately isn't like being pedantic about grammar or spelling. The words you're trying to use in your comment have precise meanings, and if you don't use them in the correct way what comes out isn't just unclear, it's nonsense.
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I apologise, I only do simple maths, like 4th roots of complex numbers, so the rigorous symbology used is extremely confusing. Like Newtons origional Momentum equattions compared to F=Ma.
Circular relativistic motion. A constant speed, constantly varying velocity. The confusion comes from, linearly, mass gets harder to accelerate the faster it goes, but in a circle, the acceleration is always orthogonal to the line of motion, so the acceleration in that direction is always at zero velocity? Therefore, does a relativistic mass have the same mass increase to a side acceleration as to a forward, reverse acceleration? I just find it strange that a synchrotron has a fairly static magnetic field strength on the outer edge, even as the momentum/energy of the particles increases?
I never read articles like this when people post them, so I'm just going to assume space flight will be powered by unicorn farts. :B
I do love Ars Technica. When all of the mainstream news, and even most of the pop science news sites, are in the habit of parroting a press release that makes some implausible claim, Ars Technica's writers take the time to actually read the paper, understand what it says, see what other scientists have to say about it, and put out a real balanced report that leaves you wiser. That's because other news sites - even science news - are all just chasing the next click, while Ars have a long history of quality to live up to.
Sometimes this means they get their article out three weeks later rather than the same afternoon as the press release. I am entirely fine with this. I've gotten into the habit, whenever I see a headline about "breakthrough battery that will let you charge your car in two minutes!" or "astronomers find star older than the universe!" or "the whole story of human evolution has to be rewritten because of this find!", of just putting it aside and waiting for Ars to do a proper report.
That's why they're the only news site I actually pay money to.
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You might check this Wikipedia page. It's not exactly a gentle introduction into relativistic angular momentum, but it might help if you understand the basics already.
Yeah...
If the only person coming up with a theory that depends on relativity to work, is a guy who doesn't know anything about relativity, at a workplace chock full of people who do understand relativity, then just maaaaaybe it's not meant to be.
I do a lot of reading about relativity and modern physics. I can explain 11-dimensional string theory to a business major. But I'm not an expert in it, and I've never taken a class on it. When I worked at NASA, I did basic stuff like aerodynamics, acoustics, and solid propellant design, which were all related to my actual education. I can have an intelligent discussion about relativity, quarks, or string theory. But if I claim to have found a way around the most fundamental laws of physics using something I read about as a hobby, then you should be suspicious as hell.
This is what happens when Flat/Young-Earth Geocentric Creationists who are politicians appoint other Flat/Young-Earth Geocentric Creationists to positions in NASA.
Propelling, you say?
https://derpicdn.net/img/view/2019/3/5/1978336.png