Warp Drive/Alcubierre drive now an actual possibity!

We cannot predict the weather for tomorrow with greater than 50% accuracy. I think predicting complex physics advancements is simply out of the question.

Every decade there is a new major theory that shakes things up, but remains largely unproven or even unprovable.

Like you said, most major discoveries are not intentional or planned. They just seem to happen as a result of people basically playing with physics and noticing things that they though should not happen the way they do.

Scientist A is trying to make a means to turn lead into gold. He/She adds ingredient B to the melted lead and discovers phenomenon C occurs. Then we have a totally new branch of science or a means to do something otherwise believed to be impossible. He/She may not have made gold, but this is how science works out.

That sort of example is just an example. It is not to be taken literally, but it conveys the process. This process happens regularly.

 

Things that seem like they will be easy sometimes turn out to be very hard, and vice versa. And that's even when we do understand the science, because it's one thing for a scientist to show that something is possible, and quite another to build a working prototype that is actually practical to use. To give a really absurd example, we may feel we understand a whole lot of the mechanics of how a star forms, but it's quite another thing to actually build one ourselves. Years ago, when you were lucky if your laptop battery lasted more than an hour and a half, they were talking about putting fuel cells into them. We understand how fuel cells work. But the trick is to get one that is small enough and cheap enough, and practical enough that you could fit it into a laptop case. And we thought that would be coming any day. But we still don't have that. Go back further, and we had jetpacks. We actually knew how to make them, we just needed to make them safe, and practical. We thought that one day, everyone would be able to have their own jetpack. Never happened, because it was an engineering problem that was never quite solved. Engineering is different from science in that there are practicalities that engineers have to think about that may never occur to a scientist. So, you can build a faster than light engine, but can you drive it without destroying yourself. How do you navigate when you are traveling faster than the speed of light? How do you stop at your destination? What materials do you need to build a structure that can keep you alive to get to your destination without falling apart. Even if you send only machines and not a human passenger, how do you make sure it survives?

And sometimes the problem is one of cost and infrastructure. It's one thing to say that we know how to build a colony on Mars, quite another to actually transport everything you need to do so, and maintain it. Generally, things like that have to happen in steps, and when the payoff is theoretical, and way, way down the line from the early stages, it's hard to convince people that it is worthwhile. Long-term planning beyond a few years, especially when you consider changing politics, economics, and so on, is very risky. At least the way things are now, you are extremely lucky to be able to plan succesfully beyond 8 years (2 presidential terms).

 

The article mentions the ring-portion of the ship would probably need to be built from Exotic Matter. What that means in science-speak, is that it needs a theoretical type of matter that we've never observed and which has physical properties different from all observed matter. Usually this means matter with negative mass (though sometimes the term is used for matter that's exotic in other ways, like dark matter or non-baryonic matter).

So what would matter with negative mass be like? Well, for starters it would have anti-gravity, and be constantly falling away from the earth. Same effect on electro-magnetism: opposite electrical charges would repel it, not attract it. More disturbingly, if you physically pushed it to the right, it would instead go left. I'm really unclear about what that actually means for the hand you used to push it, but I imagine it would hurt. Wacky stuff, that exotic matter.

The wikipedia article that was quoted a few posts ago mentioned the possibility of using tachyonic matter. Tachyons are theoretical and not-yet-observed particles that always move faster than light, and cannot be slowed down to speeds equal to or less than light. Which means not only that the moment this matter comes off the assembly line, it is zipping away from you faster than you can see it. It is, for all intents and purposes, traveling backwards through time (and, simultaneously, also traveling in the more familiar forwards-in-time fashion). It arrives before it leaves. If you could see an object made of tachyons, you would always perceive it as moving away from you in two different directions at once. Light bouncing off of where it was, and where it will be, will both arrive at your eye at the same time. Tachyons, if they exist and could be harnessed for technology, would violate causality and cause all sorts of logical paradoxes.

So while I find the article (and concept of the alcubierre drive itself) really interesting, the cynical voice deep inside me really wants to paraphrase the article as "we can totally make a warp drive any day now, we just need to invent antigravity and time-travel first".

 

I can understand where you come from, R_B.
However, I don't believe the Grandfather Paradox is true. I think we all know how that theory of time travel works.

The second theory of time travel that I know of is the bootstrap paradox, which John Connor is. No clear origin point. Exists out of the time stream.
Or the other big theory the Closed loop theory.

That's the only theory on Time travel that I believe in.

Basically, if you go back in time and kill Hitler, you immediately create an entire new universe to live in, never being able to go back home. In your home universe, Hitler still exists, but in this new one, you are now in, he never rose to power, and Stalin tried to conquer the Earth.
Wait, that was Red Alert's plot.
The big thing is that the closed Loop theory negates all potential paradoxes, and prevents causality from being violated. This of course has it's own issues, mostly going insane from never going home again.

Correct me if I'm wrong on any of this.

 

Well, the main issue with time travel is that, as best as we can tell, shit is impossible.

r_b: The really funky thing with things of negative mass can be best observed by looking at gravitational laws + acceleration:

F = [Mass of object 1 * Mass of object 2] * (some constant that's positive so who the hell cares)/(distance between objects squared, always positive, who the hell cares)

A = F/M

So, for two positive masses:
F is positive.
A is positive. This is the usual "objects attract" universe.

For two negative masses:
F is positive.
A is negative. Objects repel. Shit's weird here, but still can visualize it - its very similar to electromagnetism.

For one of each:
F is negative.
On the positive mass, A is negative. So it'll be heading off *away* from the negative mass. Ok, seems fine so far...
On the negative mass, A is positive. So it'll be heading off *towards* the positive mass. So we have two objects accelerating each other... in the same direction... potentially at the same acceleration... so they'll stay the same distance apart... and accelerate up to the limit of c? Yeah, lets not get any of this crap on us

 

I'm starting to get lost here. So much science.

 

Thank you for clearing up my misunderstanding. The effects you just explained are way cooler than antigravity, so it's a win all around. I learned something new, and I was entertained by the awesome implications of the thing I learned about. That's a good start to my day.

 

<Incorrect assertion>

 

I'm pretty sure Mining was right. The gravitational force is only half the math involved. Acceleration is determined by A=F/m. The m is mass, so it introduces another instance of a negative value. I know the detail that I'd been previously missing (which caused me to interpret the properties as 'antigravity') was the part where you divide by a negative value to determine the acceleration of the exotic matter object.

For the sake of the argument (or rather, the sake of much simpler math), assuming every variable is either 1 or -1 as appropriate. Mass is either 1 (normal matter) or -1 (exotic matter with negative mass). G and r^2 are both 1, which isn't accurate, but we don't need precision. We don't really care how fast something is moving, just the direction (which is illustrated by A being either positive or negative).

Two positive masses:
F = 1 * ((1*1)/1) = 1.
A= F/m = 1.
Positive one for A means accelerating towards the other object, the direction normally expected of gravity.

Two negative masses:
F = 1 * ((-1*-1)/1) = 1/1 = 1.
A= F/m = 1/-1 = -1.
Negative one for A means the acceleration is now in the opposite of the expected direction, which is to say away from the other object.

One positive, one negative mass:
F = 1 * ((1*-1)/1) = -1/1 = -1.
In the case of the normal matter, A= F/m = -1/1 = -1.
In the case of the exotic matter, A=F/m=-1/-1=1.
The A values are mirrored. The normal matter moves away from the exotic matter, while the exotic matter moves towards the normal matter. If the absolute value of their masses is equal, they move away at the same rate perpetually. If the absolute values are not equal, then there's possibly some sort of collision and things get much more complicated. I think.

So normal matter attracts normal matter. Exotic matter repels exotic matter. Put the two together and everything goes screwy. How cool is that?

I'll agree that seems pretty unlikely and physics-breaking, but we are, after all, talking about a theoretical substance that has never been observed and which might not actually exist.

 

The thing is, since E=0.5MV^2, and the mass of one is negative, it implies negative energy, and thus far less zaniness .

Edit: R_B:

https://en.wikipedia.org/wiki/Natural_units

and more specifically, https://en.wikipedia.org/wiki/Planck_units

So, while not general, assuming G = 1 is totally fine - you're just using Planck units .

 

Am I understanding correctly that this repulsion would happen equally on the micro scale as the macro scale? Meaning that if you had two molecules of this theoretical substance, they would repel one-another? If so, that could not be found in an environment that would support life as we know it. It would be the stuff that fucks everything up in a bad way.

And I have a question for the theoretical physicists who just-so-happen to troll gaming message boards:
What would this proposed molecule look like? Would it be made of matter not unlike the matter we see everywhere, or would it be unique in design as well as function? Would it have electrons orbiting a nucleus like everything else we know of? Or would the electrons it has be different from electrons we see everyday? (Or would it not have them at all?)

Some believe the Universe began with a thought. A concept was born and the understanding of that concept led to a framework that allowed space and time and matter to exist. So lets build the framework for crazy matter.

 

<another incorrect assertion>

 

Just to make 100% certain that I'm understanding you:

Are you saying that by my doing a separate equation of a=F/m after the F=(G(m1*m2))/r^2), I'm essentially double-dipping and applying the negative twice when I shouldn't be? That the G already did that work for me?

 

<a third incorrect assertion>

 

That was a helpful clarification, so thank you for the answer.

Isn't F=(G(m1*m2))/r^2) merely telling us the overall direction and extent of the force applied to the system as a whole? The actual movement of each individual actor seems far more interesting than the overall force being applied.

Could you perhaps propose a method by which we might better calculate the actual movement of each individual component of the system without breaking it out via F=ma (or it's related but flipped a=F/m format)? I would think that a=F/m is specifically intended to be the way that one would convert F=(stuff) into usable acceleration data, but I'm open to the notion that there could be a more technically correct method of which I'm just ignorant.

 

<a fourth?>

 

Loren, I don't have the slightest idea why you're calling F=MA a form of F=GMm/r^2. The former is Newton's second law. The latter is Newton's law of universal gravitation.

I'm not entirely sure how you got confused between then, but you've done something horribly, horribly wrong.

If you look at https://en.wikipedia.org/wiki/Negative_mass, there's analysis consistent with mine (and also R_B)'s analysis of the issue.

To incorporate vectors, I have written stuff down on paper, and scanned it in. My handwriting's awful, but it might make it more apparent.



anyway, the big thing here is that everything still works fine in the "both masses accelerate in the same direction". Momentum is conserved, as is energy.

In Loren's calculations, neither are:
Imagine the +/- mass objects accelerating in opposite directions for a time t

Then, dP+ =a*m * t BUT dP- =-a*-m * t.=a*m*t

Then, adding dP+ to dP-, we get 2*a*m*t - this number is not zero, and thus momentum is not conserved, violating a fundamental principle. Similarly, energy is also not conserved.

 

Regarding Omni's point:

At a fundamental, particle level, gravity is basically ignorable. It might have minor, minor effects, but they're on the order of - not just trillions of times less, but 10^40 times less.

So, a theoretical "negative mass molecule" would pose no issues - gravity is trivial on a small scale level. The issue comes when you have ~10^20 of these, which is on the order of 1-100g based on how large the molecules involved are. Then you'll experience some non-trivial accelerations with respect to the earth.

Well, as far as we know, all matter is negative matter . The only issues come from 'different signed' matter coexisting - but this would be possible with, for example, a 'proton' with mass 1, charge 1, and an 'electron' with mass -1, charge 1 would form a perfectly adequate 'hydrogen molecule'. Given the weirdness (and very small scales) of interactions involved, I'd rather not try and fudge my way through much more than that.

 

I just rotated it for easy reading. Your handwriting is better than mine.
Except.... "WikiDERPedia"... I am not sure if that was intentional or not, but I did actually read it.