Schneibster

I didn't even dare respond to that.

I know a senior VP Dekan should meet for the improvement of attitude. She's a redhead.

When I run a Windows box, I run Eset's antivirus; it's the lowest footprint of any of the major non-free solutions. I use browser utilities for internet security, as well as a firewall. If I can do my outgoing connection and incoming connection security at the firewall, I save CPU cycles.

On ekpyrotic theory? No, no books.

On physics, if you're working on a chemistry degree you're already getting a lot. I think the two best-known Brian Greene books are your best bet if you don't want to take on the heavy-duty math of string physics. (The Elegant Universe and The Fabric of the Cosmos.) This will give you the operating principles, and let you choose where you need to delve deeper.

If you need to beef up on the real basics, try The Force of Symmetry by Vincent Icke. No string theory in that, though; OTOH, a darn good overview of everything short of it, from a not-so-much-math perspective that won't strain your brain when you're taking a break from cramming for a mid-term. It's quantum and relativity physics for liberal arts majors. You won't be able to drive the locomotive but you'll know where all the important knobs, buttons, levers, and control wheels are.

 

I don't know what space is.

I don't know what time is.

As a consequence, I guess I don't know what motion is.

 

If you define motion as a displacement in spacetime, then you get caught because when you are at rest you still are getting displaced in spacetime. I guess again.

Anyway defining motion as displacement or change in position doesn;t help much.

And as I said, your interpretation fails.

As far as defining motion myself, I use the appropriate definition for the circumstances. And I remember it's relative. There isn't any one definition that suits all circumstances.

Well, then you're using "Lorentz symmetric" in a completely different manner than I'm used to.

So you're saying that "Lorentz symmetric" is something that can only be said about a scalar? It's not something a complex field inherits from the scalars that make it up?

And also, several parts of the Dirac field do transform. So I'm not sure what you mean when you say it "does not change under a Lorentz transformation."

I suspect the problem is deeper; that your definition of "Dirac field" is different than I'm used to.

Starting John Shirley's "A Song Called Youth," first novel Eclipse. This is the Babbage Press quarto paperback edition from 1999, not the original 1985 octavo paperback edition which I also own. I'm looking forward to Rickenharp jamming on top of the Arc de Triomphe with a battery-powered Marshall as the giant nuclear powered swastika war machines advance to demolish it. Iconic stuff.

Well, I haven't learned anything yet. At least not anything that I was wrong about.

The Dirac field is the spin 1/2 Fermi-Dirac particles, or fermions, correct?

And there are only two spin moieties, half-spin and integer-spin, correct?

And the integer spin particles are the bosons, which are in the other moiety from the fermion field we are discussing, correct?

And this means that the most important difference between the two biggest moieties of particles, one of which represents classical "matter" and the other of which represents classical "energy," is spin, correct?

And spin is, not merely affected by but entirely due to Lorentz symmetry, correct?

So how can you claim the Dirac field is not relativistic when its most basic character, its spin is determined by the symmetry of special relativity, the Lorentz symmetry?

Biscuits 'n' gravy with scrambled egg beaters and turkey sausage patties.

I protest; this is not a "quick physics question" but one of the most profound subjects in physics today!

Not that that's bad.

ajb, pretty sure this one predates the Landscape. I think the documentary's talking just about straight M theory, and cut it very short; perhaps they didn't even talk about what the string theories are that make the parts of it we've figured out up, just did a handwave like many such programs do, and went on to the ekpyrotic hypothesis which was what they really wanted to talk about. (And of course, you're absolutely correct, it is, in fact, the ekpyrotic hypothesis they're talking about. I have the impression it's the main part of the theory.)

pyroglycerine, ajb is too modern for your documentary; he knows too much! Your program covered a very narrow piece of current cosmology, a hypothesis that has been put forward by a small faction. However, there is some evidence to indicate that they may be correct, but only looking at things from one very narrow perspective; their idea is likely to actually be one among many explanations, all correct, just as (for example) both the field and particle descriptions of elementary physics are two facets of the same truth.

Just at the moment, however, cosmology has looked away from this hypothesis and is looking at data that is emerging from the Sloan Digital Sky Survey, in a program called "BOSS." I suspect we'll see the ekpyrotic hypothesis again, but at this point most cosmologists and astrophysicists are looking at this emerging data source since it is pretty much fountaining new data forth. Oooohhhh, shiny.

I'm going to make my guess that it's a reflection from a polished rock. I think I saw someone say there was a picture from a different perspective, which indicates a different location on the CCD; and it's in the same location against the background; that would rule out hot pixels except as the most astronomical coincidence. That is assuming the statement that there's more than one picture shown in that article is correct; it may not be. I haven't checked; I'm taking LaurieAG's word for it.

That sounds okay, but of course no details here.

 

 

Okay, but maybe not worded great. The Dirac carries a representation of the Lorentz group which is (part of) the group to do with special relativity.

 

 

Okay, for a test particle we can think of mass as the "conserved charge" related to energy-momentum conservation.

 

 

 

 

So energy-momentum acts as a source for gravity okay.

 

 

And the above tells us that the Yukawa coupling depends on acceleration?

No. That's the preliminaries. We've never talked deeply about this stuff before so I don't know how to gauge your experience. I think we agree as far as that, remembering my mistake confusing the Ricci and Einstein tensors, and that you'll agree to what you see there so far.

Except for the part about relativity and the Dirac field; I think we need to thrash that out first. Maybe I've made a mistake there. If so there's no point in going on; that's the mistake, I learned something, and since my assertion is based on it, obviously my assertion was wrong. This is why I'm being so finicky.

Post 75, please?

Sounds about right to me, imatfaal.

I thought up an explanation for the flames, it's just a guess but unless it's some sort of hybrid thing this explains them: they're accelerating an object to hypersonic velocity in a tube; the gas law says the air in that tube is gonna get very hot, and if the projectile is supersonic the air can't move out of the way. At hypersonic velocity, I bet it might even get plasmatized. Doesn't that make sense?

You're talking about the math. The derivation of the mathematics is not the definition of the physical behavior.

I'm talking about the field. And I'm talking about relativity and spin. You can't have a spin 1/2 particle/field without defining spin, and you can't have spin without relativity. Simple as that.

And I'm still waiting for what's wrong with post 75. (Sorry for my mistake.)

My mistake, post 75.

Since you've mentioned the Dirac field at the end of your last two posts, and still appear to feel that the Dirac field is not Lorentz symmetric, I will remind you that spin is based on the Lorentz symmetry, and for the Dirac field to be non-relativistic, it must, therefore, according to you, not have a spin. I don't think you've thought this all the way through.

Edited to add, for the benefit of observers: spin is due to the fact that you cannot replace two successive Lorentz boosts with a single one; if you do, you must add a rotation. This is a consequence of the Lorentz symmetry. And that rotation is spin angular momentum. Since the very definition of the Dirac field is that it has spin 1/2, as opposed to the boson or Bose-Einstein field which has unitary spin, special relativity enters firmly into both the Fermi-Dirac and Bose-Einstein fields at their very most basic definition. It is not escapable by any trickery at all.

Matter follows the least energy geodesic.

Other matter warps the least energy geodesic's shape.

So does acceleration.

This, essentially, is General Relativity; I certainly don't mean to imply that's all there is to it, but it's the most important concepts of it, idontknow.

The best answer to the OP is, I think, "yes."

i mean to be somewhat amusing, but not sarcastic; in fact, it can be interpreted either way, theoretically.

However, although we've figured out how to represent it as a field theory (General Relativity), we have not figured out how to represent it as a quantum theory (Quantum Gravity), and thus we cannot even imagine its Gravity Quantum Field Theory. We can only speculate, and try to constrain whatever eventual quantum gravity theory we will eventually, when we figure out the math, discover.

This theory will obviously deal with quantization of the universe that we perceive as a superposition of fields. Techniques as powerful as the Yukawa coupling theory that allows scalar fields to be related to four dimensional tensor fields like the Dirac field that describes fermions will be required. We can, in fact, knowing what types of fields are involved, make good conjectures about what a final theory will look like based on what we have now. We are, in other words, quite close. We may in fact already know the required techniques and not yet have applied them in the correct manner.

I don't expect to be famous or figure anything out, but I think someone might before the day I die. This is a truly awesome time to live; I have seen the confirmation of the Big Bang, and of the Inflationary Epoch. I am stoked.

 

On Earth nor anywhere else, the travelling wave reactor doesn't work.

 

Because...?

Frankly on just as much evidence as you have presented I say it does work and you are lying.

Update: it has been brought to my attention that this could be interpreted as me saying you're lying.

I'm not.

I'm saying, rhetorically, that you don't have any evidence. My apologies for any appearance of insult. My intent was to be sarcastic, not insulting. Please forgive me.

It's a justification for these small ones. However I think they've got big ones we're not seeing any videos of.

How do you know that a troll only cares for the disruption, no matter what? Have you ever trolled anyone? Have you never met a troll with a conscience? You're attacking a strawman, if I may say so.

Good question. +1.

I believe your first statement is correct: the aim of the troll is to disrupt, annoy, irritate, and create drama.

But I think your hypothetical "good troll" is not truly a troll. I'm not saying they're not trolling; they might be. But they're not there to be a troll. The true troll thrives on watching other people fight.

 

if you already think women have faulty (or at least different) logic.

 

I don't. I think there is a cultural tendency to encourage them to think and behave in accordance with their emotions rather than their rational thoughts; some (most, unfortunately, in my generation; this seems to be changing) succumb to it, some do not. Independent dispassionate thought is certainly not the sole province of men, and no more is irrational, herd-driven, emotional reaction the sole province of women.

I think it's pretty clear from the way they're talking to the reporters from FP that they figure to make them a lot bigger.

I'm interested in the magnetic engineering, actually. It has applications in space flight and fusion. A true railgun uses electric or magnetic linear acceleration. I would expect the accelerator to run half the length of a ship or more, with a final (comparatively) short barrel to provide final direction. I wouldn't expect more than a few degrees' off-axis aiming from the main axis of the ship. I'd expect a projectile in the neighborhood of a ton.

I'm thinking this may be more of a rail-boosted gun, with a sabot penetrator. Sexy, but not really a "rail gun." Just kind of a hand-wave at it.

I gotta go with swansont here. I'll only make one minor point: Mars does have an atmosphere so theoretically there could be some scattering, and there is also dust. Although Martian dust storms are pretty impenetrable (as I have had many occasions to swear at after spending all afternoon getting prepared and then finding it impossible to see anything but a reddish-orange disc).

Later: Ice? Steam? The rectilinearity of it does, as swansont says, look like a couple hot pixels.

How many pictures have the feature in them? Has NASA said anything? The site we're looking at is a bit... errr, sensational. Not to say anything nasty about someone's favorite site.

Sure.

You're still not answering my question. I started to do what you ask ("please explain"), and you didn't agree with me on the basics in post #77, and you won't tell me what you disagree with. You keep bringing up extraneous material. I'm sorry, I don't intend to let go of this until you've answered it.

I don't build houses on foundations of air. Until you agree with the basics I don't see how you can object to their results unless you say what basic you don't agree with.

Which one of the basics in post #77 do you disagree with?

I am becoming impatient myself, now. If you think can show me something wrong with my reasoning, then show me something wrong with my reasoning; so far you can't.

Oh, and incidentally I made another mistake; I should have said Einstein tensor, not Ricci tensor. It's actually mostly the Ricci tensor but we should be rigorous. It does not, however, make any difference to my point.

And I do not intend to move on to your other points until this is cleared up. Sorry but if you're going to tell me I'm wrong you're darn well going to tell me how.