151–160 of 205 posts
"9. Why isn't there a simple explanation of how it's supposed to work without violating the laws of physics?"
"If the new drive results continue to be replicated, then theory may have to catch up."
Reminds me of the quote: "In theory, there is no difference between theory and practice. But in practice, there is."
The most important question that should have been top center: with reactionless propulsion it is possible to create a free energy device. Attach the thruster to a wheel. When the thruster is firing, it consumes constant power and the wheel accelerates, spinning ever faster. The wheel can be attached to a generator that produces power which is thrust times the rim velocity. Thus, after a certain speed, the wheel produ…
I"m not following why you think the wheel generator will produce more power than is required to spin the wheel in the first place. Friction is a pretty big issue in your scenario. It seems orthogonal to the actual results.
Power of the wheel = thrust * rim velocity. That's just basic physics you should learn in high school.
P_1 = F * v
The claimed thruster produces a constant thrust for a certain power, let's use a factor k for that:
P_2 = k * F
F * v = k * F
v = k
We can also have some friction, let's say the wheel generator is 50% efficient. We then need to run the wheel twice as fast to get the same effect.
There actually exists a trivial "reactionless" thruster if we use a flashlight and the light pressure. But it turns out the velocity is the speed of light then.
Ugh. That's a Buzzfeedy title if ever there was one. I'm surprised it isn't: Space Scientists Don't Want Obama To Know These 10 Secrets About Warp Drive
The most important question that should have been top center: with reactionless propulsion it is possible to create a free energy device. Attach the thruster to a wheel. When the thruster is firing, it consumes constant power and the wheel accelerates, spinning ever faster. The wheel can be attached to a generator that produces power which is thrust times the rim velocity. Thus, after a certain speed, the wheel produ…
At least one of the theories on the article talked about pushing on virtual particles, like a submarine pushing on the water around it. This would imply to me that efficiency goes down with speed. Just a thought.
(1) News article! Prevailing view of physics overturned! Etc! Etc! Etc!
(2) Many excited comments!
(3) Much less excited comment, pointing to skeptical remarks by well-known professional physicists (e.g., John Baez, Sean Carroll).
(4) Much to-and-fro. People who once saw a Discovery Channel special on physics now appear to believe that they're in a better position to evaluate the new claims than the people from (3).
Now, points (1) and (2) do sometimes happen, without points (3) and (4).
For instance, the neutrino faster-than-light claims attracted very cautious comment from professionals. In other words, point (3) was absent or rather muted. That's because the people who'd done the experiments were known for being extremely careful, and were, in fact, very cautious in their announcement.
That kind of thing is genuinely exciting, and worth discussion.
Another nice example of an exception is the Alcubierre drive. It satisfied (1) and (2) (or the 1996 equivalent), but (3) was absent, except that professionals noted that the drive required the stress-energy tensor to have some unusual properties, not satisfied by any known substance. Indeed, Alcubierre pointed this out himself.
Again, genuinely exciting, and worth discussion.
But when the professionals are loudly deriding a result, it'd be nice for the amateurs to make a serious attempt to understand why, and not just airily dismiss it.
Earlier quoted context omitted.
Baez is right, there's no such thing as "virtual plasma". Just Google the phrase.
To expand on that a little: http://blogs.discovermagazine.com/outthere/2014/08/06/nasa-v... >>In the paper by White et al, they also write that the Cannae Drive “is producing a force that is not attributable to any classical electromagnetic phenomenon and therefore is potentially demonstrating an interaction with the quantum vacuum virtual plasma.” That last bit stopped me. What’s a quantum vacuum virtual plasma? I’d…
Earlier quoted context omitted.
I'd say that it's about on par with the faster-than-light neutrinos caper (tiny effect, violates known physics, probably result of experimental error, ...). Both would be very exciting if actually confirmed, but I personally found/find the chances too slim to (yet) get excited.
Wasnt the faster-than-light neutrino myster solved? It was an optical cable not plugged in all the way.
Earlier quoted context omitted.
My final sentence was getting at a mechanism by which momentum is conserved in this system. If you assume that time is quantisable (big assumption, I know), and that the planck time is lorenz invariant (not as much of an assumption), then an EM wave at a fixed frequency moving from one reference frame to another could experience quantisation due to the shifting time-base, resulting in an apparent net deceleration - r…
Well, the relativity principle states that things don't "move from one frame of reference to the other". You choose a frame, and observe things on that frame; changing the frame of reference is your choice, and must not alter the results in any way. Accepting a flaw in conservation of momentum is already hard enough without you (and the original paper) imposing a flaw on the relativity principle to explain it.
People used to say that about Newton - until experiment proved that he didn't have the full picture.
It's highly improbable that relativity is any different. Yes, it gives demonstrably correct answers, but that doesn't mean that it holds in all cases.
I mean, why would we be even talking about LQG if we thought relativity gave the full picture?
You're right that I was wrong to say it moved from one reference frame to another, which is clearly bollocks - the EM undergoes an acceleration to relativistic mass, then a deceleration.
Earlier quoted context omitted.
I asked a particle physicist to compare the validity of this to the faster than light neutrino claim that came up and his response was: "Although several people are drawing that comparison, they're really not in the same class. OPERA did an extremely thorough analysis of the faster than light neutrino result before they published. In the end it turned out to be a very subtle experimental error that cause the problems…
But there's three independent labs working on this concept, plus NASA. _Who_ is lying, the EmDrive folks? And if they are, then how are NASA, the Chinese and the other lab all replicating their results?
I don't know what's going on with whoever is doing this at NASA, but the joke of testing IN A VACUUM CHAMBER while not actually pumping it down is ridiculous. These people are scientists who have access to the device - how did they not turn it on? For lack of a suitable capacitor? That's a nothing part for such a massive potential breakthrough.
Here are two nice posts by physicist John Baez with some reasons to be skeptical about the "reactionless drive": https://plus.google.com/117663015413546257905/posts/WfFtJ8bY... https://plus.google.com/117663015413546257905/posts/C7vx2G85...
I'd never understand how intelligent and educated people lose it completely when it comes to Physics. They've been exposed to some PopSci tales not meant to be accurate at all and then feel entitled to be right when they figure out some nonsensical consequences by themselves -no proper maths involved ever-. It's depressing. Baez is right, of course. I've been checking the (Word-generated) "papers" from this guy's gro…
Not defending this particular paper, but I'm curious why you highlighted the fact that it's written in Word. Just about everybody in physics these days uses Word to compose papers (Word + Mendeley is a dream, by the way). Maybe you think he's not a 'real man' because he doesn't sling raw LaTeX?