What we know about the EmDrive and Cannae Drive • Hacker News Board

Re: What we know about the EmDrive and Cannae Drive

#151

Post by madaxe_again » Sat, May 02, 2015, 9:13 AM UTC

Steuard wrote: post #4

This is not worth getting excited about. Really. Extraordinary claims require extraordinary evidence. These drives would violate conservation of momentum.[0] Conservation of momentum is built in to the known laws of physics at an extraordinarily deep level. It is obviously not impossible that our known laws are wrong, but the alternative would be to somehow produce a radically different set of physical laws that neve…

Also, as everybody knows, it is impossible that the earth could be orbiting the sun rather than vice versa - all books on the subject confirm it, and this would totally defy the theological principle, which is certainly impossible.

Only hereticks waste their time thinking of such stupid ideas as a heliocentric solar system. They should spend their time productively, and cut up some cats for their humours.

Re: What we know about the EmDrive and Cannae Drive

#152

Post by madaxe_again » Sat, May 02, 2015, 9:15 AM UTC

api wrote: post #137

raverbashing wrote: post #86

Earlier quoted context omitted.

> When you get to the fringes-- that's where the action is-- but it's also where you can have confusing or odd results. I think this phrase sums it the best I also usually remember that the Casimir effect, a tested and true effect, used to take a lab of experts some years to reproduce results

Was the Casimir effect highly controversial like this? Is there a good example of a discovery that was both challenging to reproduce and initially dismissed by many but was later vindicated? We hear lots of examples of the inverse of this like Pons and Fleischmann but I'm sure there have to be cases like this.

The roundness of the earth.

Heliocentric solar system.

Circulation of blood in the body.

Yes they're "a long time ago" (really, a few centuries isn't a long time), but they're the tip of the iceberg of contested knowledge.

Re: What we know about the EmDrive and Cannae Drive

#153

Post by FrankenPC » Sat, May 02, 2015, 9:36 AM UTC

What's the deal with power scaling? The OP says: 50W of power = 50uN. That's 0.05mN. 2500W of power = 750mN

2500W is 50x 50W of power. 0.05mN x 50 = 2.5mN, not 750mN.

That's a hell of a ramp up in thrust. Does it keep ramping the more power you put into the cavity? If so, how much power is required to say get a fighter jet to fly which is around 100,000N of thrust?

Or is my math WAYYY off?

Re: What we know about the EmDrive and Cannae Drive

#154

Post by marcus_holmes » Sat, May 02, 2015, 11:54 AM UTC

madaxe_again wrote: post #152

api wrote: post #137

Earlier quoted context omitted.

Was the Casimir effect highly controversial like this? Is there a good example of a discovery that was both challenging to reproduce and initially dismissed by many but was later vindicated? We hear lots of examples of the inverse of this like Pons and Fleischmann but I'm sure there have to be cases like this.

The roundness of the earth. Heliocentric solar system. Circulation of blood in the body. Yes they're "a long time ago" (really, a few centuries isn't a long time), but they're the tip of the iceberg of contested knowledge.

plate tectonics - massively, enormously controversial, it split the entire earth sciences down the middle with much shouting and name-calling. You can still find old geography textbooks that don't refer to it at all. Turned out to be true and a generation of earth scientists went muttering expletives into retirement.

Re: What we know about the EmDrive and Cannae Drive

#155

Post by Intermernet » Sat, May 02, 2015, 12:12 PM UTC

Confusion wrote: post #148

Retra wrote: post #134

Earlier quoted context omitted.

That is one of my arguments against homeopathy: We've got a world full of bright young medical students looking for cheap and easy research to do that will lead to positive results. If they haven't proven homeopathy effective, it's because it isn't.

There is no cheap and easy research in medicine when it comes to showing that some substance heals people, which is what if often comes down to, because the actual mechanism is unknown. You can't show something as simple as aspirine 'works' by setting up a lab experiment without test subjects. And as soon as you involve those, it becomes legally complex, expensive, time consuming and hard. You simply can't compare me…

I understand what you're saying, and agree with you on general terms, but this argument doesn't apply to homeopathy.

Homeopathy doesn't claim that "some substance heals people". It claims (according to Wikipedia [1]) "a substance that causes the symptoms of a disease in healthy people will cure similar symptoms in sick people".

It's fundamentally flawed, and despite revisionist practitioners, has not yet managed to raise it's head above "pseudoscience" status.

It shouldn't really be mentioned in the same sentence as research that is actually trying to determine if a substance has an effect, even if that research is flawed. Said research and homeopathy aren't really playing on the same field. It's like calling religion a science. It's based on a premise that can't be questioned without throwing out the entire idea.

[1]: http://en.wikipedia.org/wiki/Homeopathy

Re: What we know about the EmDrive and Cannae Drive

#156

Post by wnkrshm » Sat, May 02, 2015, 1:10 PM UTC

MertsA wrote: post #110

tlb wrote: post #7

1 micronewton / watt is a surprising amount of thrust. The implied velocity of whatever it's pushing against is 1e6 m/s, which is 1/300 the speed of light.

What's more surprising is that every number I've seen for the higher power Chinese test was 750 milinewtons for 2.5kw of power. That's 300 micronewtons per watt of power.

Are you sure? 300 µN per W would equal a photon drive's efficiency, with 300MW = 1N.

Re: What we know about the EmDrive and Cannae Drive

#157

Post by Intermernet » Sat, May 02, 2015, 2:01 PM UTC

scott_s wrote: post #95

syncsynchalt wrote: post #84

Earlier quoted context omitted.

Given the small amounts involved, it's worth the money just to figure out the source of experimental error. NASA isn't giving money to random kooks off the street, these are actual physicists in labs doing the work.

Steuard is too polite to point this out himself, so I will do it for him: he is a physics professor. That the amount of money is small is a measure of how incredibly unlikely he thinks any useful result would come from the experiments.

Steuard himself would hopefully point out that although being a physics professor grants his opinion a greater weight than those of us who are less informed, to claim that he is automatically correct would be fallacious.

Politeness in this regard is preventing appeals to authority.

I personally disagree. The money has been allocated to a section of NASA designed to research exactly this sort of theory. Pulling funding from these people would be like telling Ernest Solvay to put away his wallet.

Re: What we know about the EmDrive and Cannae Drive

#158

Post by Intermernet » Sat, May 02, 2015, 2:14 PM UTC

Retra wrote: post #136

issa wrote: post #76

Earlier quoted context omitted.

This is exactly my attitude. I'm shocked that people don't think twice about spending money on frivolous or even harmful things, but balk at the idea of paying for pure research.

You don't want to shovel fuel into a crackpot industry. That actually prevents real science from being done.

Being snarky, but a lot of the world's consumer economy can be seen as shoveling fuel at crackpot industries.

You're correct, but I'd rather a few million dollars going to this research than a few million dollars going to some magnetic-healing-band toting pseudo-guru.

The "first world" wastes ridiculous amounts of money every second. Can we divert at least some of it to disproving crack-pot scientific ideas? It'd at least be entertaining (like Mythbusters on steroids!).

Re: What we know about the EmDrive and Cannae Drive

#159

Post by GhotiFish » Sat, May 02, 2015, 4:32 PM UTC

jdjdps wrote: post #146

Steuard wrote: post #4

This is not worth getting excited about. Really. Extraordinary claims require extraordinary evidence. These drives would violate conservation of momentum.[0] Conservation of momentum is built in to the known laws of physics at an extraordinarily deep level. It is obviously not impossible that our known laws are wrong, but the alternative would be to somehow produce a radically different set of physical laws that neve…

I get really tired of these ignorant psuedo sceptic responses. It's so obviously a straw man attack it makes me cringe. Why are you so set on assuming that it is violating conservation of momentum? No one of import is claiming this. My god, authority must always be right! All who move beyond appeals to authority when constructing arguments must be decried as beyond the fringe! Heathens! Infidels! Traitors! Expell the…

I got the same response when I informed /r/science that "No, no one in the OPERA Experiment actually believes that neutrinos are actually going faster than light and breaking special relativity, they're asking for input on what went wrong with their observations"

I got a tirade of responses just like yours informing me that I'm a biggot, childish, close minded, backwards thinking, co-dependent on authority, cretin who will be the responsible for the downfall of humanity. ect. ect. ect.

I believe I got down to -45 karma on that post, my lowest score ever, and I wasn't being aggressive or hauty or anything. I was just saying "they're just looking for explanations on their observations, there's no way it's actually happening."

I never got an apology for that, strangely enough.

Re: What we know about the EmDrive and Cannae Drive

#160

Post by api » Sat, May 02, 2015, 5:14 PM UTC

madaxe_again wrote: post #152

api wrote: post #137

Earlier quoted context omitted.

Was the Casimir effect highly controversial like this? Is there a good example of a discovery that was both challenging to reproduce and initially dismissed by many but was later vindicated? We hear lots of examples of the inverse of this like Pons and Fleischmann but I'm sure there have to be cases like this.

The roundness of the earth. Heliocentric solar system. Circulation of blood in the body. Yes they're "a long time ago" (really, a few centuries isn't a long time), but they're the tip of the iceberg of contested knowledge.

Those all seem long ago. Are there any in the last, say, 50 years? That's when I'm having trouble thinking of any.

Also the roundness of the earth was never as far as I know controversial among the learned. Heliocentricity was only controversial for religious reasons.