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[Il Palazzo]

So, let me get it straight, you advance the idea of ether permeating all of the space, yet being blown away by the solar emissions, which is why we can't detect any?
Whouldn't that meant the collecitve radiation of all the stars in our galaxy would blow all the ether away from the intra-galactic space, in which case there wouldn't be any ether anyway?

[Starver]

[Darnit, Posted this (or tried to) just as I went home last night, and this morning I find I got a "2 new replies" response back.  Who knows how many more occured since then..? [Answer: 50]  Still, I continue to be willing to show my ignorance on this aspect of science, so I'll post now and read the interims as soon as I can.]

Haven't seen the original discussion from which this appears to have arisen, so right now I'm trying to reconcile whether the "negative mass for anti-matter" explanation totally works.  In interactions between regular matter and anti-matter, I can see how the negated negative 'emulates' the normal positive that would have been present in purely norm-norm interactions, but does it also work in an anti-anti interaction?

I'm trying to remember back to my own grounding in the hypothetical exotic (not specifically 'anti-typed') matter with supposed negative mass.  IIRC, such masses were [repulsive to and/or repulsed by] normal matter, whether considered 'normal' or anti-versions.  And at one point (at least, if not now) considered to be mutually repulsive to fellow mass-negative particles, such that (one assumes) they would tend to push themselves apart away from each other (and any other matter) to become a thin smear of almsot intangible exoticness all across the universe.  But I must admit that I'm not familiar with current theories on this subject, and that might just have been an early attempt to cater for the effect that is currently attributed to dark energy (the sort of anti-Casimir effect that powers the various phases of unusual universal expansion).

I think some of this has to do with whether it is negative gravitational mass and/or inertial mass (or is it the active/passive components of the gravitational mass side?).  Though I think some combinations produce interesting results such as a negative-mass particle accelerating away from a same-magnitude positive-mass one at exactly the same rate as the positive is falling towards the negative (or vice-versa?), in a never-ending and ever-accelerating (relativistic limitations aside) chase across the universe.

[Starver]

Besides, let's say, you're playing russian rulette, and after five turns without killing yourself or the other guy, you've got the revolver again. Somebody gives you a choice to quit or keep playing. Mathematics tells you that there is a bullet in the chamber, physics tell you that pulling the trigger will blow your brains out. But you'd still not believe it, because you need an experimental evidence?

Not to reduce your argument here (and it's slightly necroing the analogy, which hasn't got anything to do with the original point of this thread), but some 'versions' of Russian Roulette involve spinning the chamber each time.  (And it is said that with a well-oiled gun, the weight of the bullet can bias how the chamber comes to rest.

And, then again, some (alleged) Darwin Award nominees have played Russian Roulette with weapons that use ammo clips with only one bullet in[1].  Meaning that (depending on whether it auto-chambers the slug or not) either the first or the second attempt to fire is virtually guaranteed to be the fatal one.

[1] Yes, you could mix a live bullet with some blanks (non-firing types, because a blank blast at close range isn't a piece of cake), but I feel that:
a) I'm going to far with the increasingly off-topic analysis of this  analogy, and,
b) I'm generalising so much that someone is going to complain that "but, with an H&K blah-de-blah, it's actually the case that...".  Perhaps best to ignore me if you feel I haven't covered it correctly...

[DreamThorn]

Funny to see an off-topic post in a thread formed from off-topic posts in another thread. 

[Sean Mirrsen]

I'm not promoting aether. Aether is a stupid idea. I'm talking about ambient energy. There's just no better word for it than aether. The sun's emission would negate any velocity the energy would acquire relative to the Earth's or sun's orbital motion. I can't whip up a definite explanation at the moment. I'll try to, but the following post may be a touch incoherent.

I'm thinking of energy as this sort of ocean of space. It's got flows and streams, because matter releases or accumulates energy when being interacted with, being simply energy packets spinning in undeterminable ways. The Sun releases its stored energy as various emissions and particles, and these all add to the ocean of energy. But if we try to determine the energy's properties, it is like a very loose gas rather than a liquid. If you push an object through it, the front of the object with accumulate energy with no drag beyond the very miniscule amount of energy acting upon it. Up until a certain point, this "drag" increases slowly, the matter absorbs or simply scatters energy. Beyond this point, however, matter and energy begin to be significantly affected. As the speed increases, the energy buildup on the front creates an effect not unlike compression of air. Mass increases rapidly, forming matter from energy not by weird spinning, but by sheer speed and energy income. What happens later is beyond me at the moment.

Light, be it lightbulbs or lasers, is simply an energy emission in this odd 3D waveform thing. But through this mass-accumulation process, its peaks collect energy, and the photon forms - it's not really a particle, but it acts like one because it has acquired mass. I've still to form a concrete opinion on whether it somehow begins spinning in a way resemblant of a particle, or simple accumulation is enough to form it.

Ambient energy exists everywhere. Ambient energy is what the universe would be reduced to in the event of heat death. If ambient energy is water, particles and matter are ice, figuratively speaking. I'm trying to form a coherent set of rules that would explain the observed speed of light and EM emissions, as well as other possible scenarios, while still being partially connected to this view of the universe I've worked out with time. If all else fails, I'll still be able to use it in my Multiworlds setting.

[DreamThorn]

Off topic:

   I was just thinking it would work better in your MultiWorlds setting.

How much time does it take to run your RTD?  I have been considering running my own, but have no idea whether it is viable.

On topic:

I was hoping to have a fun physics discussion in this thread.  Instead I discovered that I have become very rusty with physics, and that other people that post here are determined to have me teach physics to them.

Fortunately we can now switch to your ambient energy idea, as well as other 'alternative' theories.

Do you mean that space is made up of energy?  I would have to agree with that, but for very different reasons.

An idea that I have had rolling around in my head is that space is an illusion created by potential energy.  This unfortunately does not explain rotation or the existence of three spatial dimensions.

[Starver]

Forgot I was still way behind catching up.  Pre-ninjaed with the following.  So you can skip it if you want.

Spoiler (click to show/hide)

So, is anyone able to explain to me the twins paradox?

I personally don't know why they call it a paradox.  Maybe it's because they assume that it's just relative speed that should cause each twin to time-dilate as observed by the other, i.e. if two twins, are made to pass each other at a significant (but constant) fraction of the speed of light (and are considered 'synchronised' immediately before they pass) then they would see each other age less than themselves.  And the same would apply whether one twin were moving or both.  To the view of an external observer, who may or may not be moving themselves, you can never really say that you are stationary, just work on the assumption that you are if you are not accelerating in any way.

Assuming the twins are given identical 'acceleration patterns', in their respective round-trips, then when they meet up again, they will remain synchronised.  For each twin, the altered perspective of time passing for the other twin when the distance is widening retreating will (to cut a long story far too short) reverse itself when they distance narrows again.  Kind of like how the doppler effect on a siren on an emergency vehicle would mean that you'd end up hearing exactly the right amount of warbles overall, as you rush away from it and then it catches back up to you (assuming travelling below the speed of sound), although you'd get a lower frequency than normal at first, then a higher than normal one later on.  (This would also apply to a wrap-around universe, as the twins see each other converging from the opposite direction that they departed, with the caveat that there's probably still a 'delayed' image visible in the direction of departure, which eventually converges with the delayed 'echo' of themselves, should you be able to see that far.)

But with reletivistic effects, it's also acceleration that's the crux.  Put (a little too) simply, acceleration with respect to a frame of reference is the additional key.  Usually looked at as linear acceleration, but change of velocity by turning to a different heading or acceleration due to gravity while otherwise standing 'stationary' on the surface of, e.g., a planet also count.

With the twins, the twin on the planet experiences just the (trivial, almost inconsequential) acceleration of gravity.  The twin who is sent to Alpha Centuri and back in (say) a 10 year round trip (1 and 1/4 years longer than light would take, IIRC) might experience accelerative dilation to a factor of roughly (if I've not messed up in the relevent mental arithmatic) 1/4.  i.e. 2.5 years passes for the acceleration-affected twin, the one who had to somehow accelerate fast enough to get to A-C and back (including deceleration half way through each journey, which is still an acceleration, just in the opposite direction).

If it's a 100-year round trip, for the 'just round the corner' trip to Alpha Centuri, then (human longevity aside) we're talking about near 99% time synchronisation, because the twin hasn't needed to accelerate much.  (I could work out what travel time a 1G acceleration/deceleration would give, but I'm already waffling too much and something's niggling me that I've got the equations a little skewed anyway.  Still, it's representive if not strictly accurate.)


I think probably what you want to look at, Twins Paradox-wise, is the experiments in which the atomic clock was flown round the world and compared with its 'twin' left stationary on the ground.  IIRC, the ground-based clock experienced the small acceleration-due-to-gravity dilation, as normal, while the flying one marginally less of that (due to average altitude being greater) but had a dilation effect of its motion.  Each effect was very small, but even when combined in opposition it was detectable by the accurate timepieces.

And of course moving (or rapidly 'jiggling', I suppose) one end of a wormhole while letting the other stay at (relative) rest is a classic method of giving you a time machine.  Wormhole physics allowing, of course.

[Starver]

At the risk of being pre-ninjaed on another item:

Btw. Black holes. If it wasn't for all the random atomic crap orbiting them, they'd be perfect for catapulting off into space with the gravity slingshot. Or not. I suspect the gravity gradient would become too steep near the thing's surface, and the ship would be quite effectively torn apart when its bow starts to weigh twenty million times more than its aft.

That's where the size of the black hole matters.

IIRC (and calculate correctly, also), the bigger the black hole, the further out is its point of no-return but the gradient is less extreme at this point.  So you can (the doomed space-junk and radiation in the accretion disk and polar flares aside) get quite close without the problem of spaghettification.  But you're going to have various other issues to deal with, like the relativistic 'doppler' aging the extremities of the ship differently, meaning you could go into the hold for a few minutes and arrive back a month later, in the right eventualities.

(Imagining designing a ship's systems to be hardened against these problems?  The optical and/or electronic communication lines would need to be able to send/receive signals at vastly different frequencies/baud from the nominal design as required, for a start...)

[dreiche2]

Understanding quantum theory requires only understanding that you cannot know everything at once.  Knowing one thing makes other things uncertain.  Although, with entanglement, this sometimes works the other way around.

Well, the interpretation of QM is up for debate. I don't believe anyone really understands it, even if some might claim so. Maybe that will change at some point, but it could also be that certain aspects are just too weird to really be comprehended by our brains, and can only be described with maths. Sean, if you want to come up with new weird theories, QM would be a much better playground than relativity 

Proving that we are handling zero incorrectly is real simple though:

f(x) = x
g(x) = x - 1
h(x) = f(x) / g(x)   => has an asymptote at x = 1
h(x) * g(x) = f(x), except, at x=1 it has no value.

Shouldn't dividing and multiplying with the same value return one to the original value?  I am quite certain that has to be in the definition of division somewhere, and that it should count for all real numbers.  Maybe I should look it up.

No. Dividing by zero is simply not defined. The expression of h(x) is simply not defined at x=1. You might as well have written h(1) := 'spaghetti'. Or like the logarithm is not defined for x<=0. Asking what log(-1) / log(-2) is is meaningless as long as you haven't defined the logarithm for negative numbers. And then, in your case, defining a new expression by multiplying one that is not defined at x=1 (h) with something that is defined at x=1 (g) doesn't automatically define the value at x=1 for the new expression. Much as log(x) * x is still not defined for x<0.

And, according to wikipedia, division by zero is still not defined even for the extended real numbers, because not all functions that are unbounded for x->0 actually approach have either + inf or - inf as limit. Also, the extended real numbers are not a proper ring anymore, i.e. multiplication is not properly working with them.

In the most general sense, you define multiplicative operations on abstract mathematical structures called rings, which by definition have a multiplication and an addition operation, and contain both a additive identity, a '0', and a multiplicative identity, a '1'. The next more complex structure is called a field (like |R, or |C), there you have for almost each element a multiplicative inverse, i.e. for b there exist c so that b * c = '1'. You define division by multiplication with inverses. However, the aforementioned statement holds true only for all elements apart from the additive identity, the '0'. I.e., in the most general definition possible of what multiplication means, the additive identity does not have an inverse. And thus dividing by zero is not defined.

Nor can this easily be fixed. On the real numbers, the square root of negative numbers is not defined. You can extend the real numbers to the complex numbers, and on that field the sqrt of all numbers is defined. And the complex numbers are still a nicely behaving entity, a field, where multiplication and addition are defined everywhere etc.

You can extend the real numbers with +- inf, but what you get is not a well behaving field or even ring anymore, no matter how you try to fix that. You might as well have extended the real numbers with 'spaghetti'. Well, it's a little bit more useful because you can still compare real numbers with inf (< and >) and define at least some addition and multiplication rules with them, plus you get some interesting topological properties, but arithmetically the whole thing is a little bit of a hack.

[Starver]

Yeah, this is kinda odd. I'd imagine that for a pilot travelling at C, length contraction would kick in to compensate for the limit. So you'd see sprite planets. (correction: you would if you could) Fun.

Travelling at C, infinite external time would pass while you were still frozen.  The entire universe would pass you by before even the concept of a blink of an eye had managed to pervade your particular frame of reference

Though I'm not averse to allowing that you might have a frame of reference, within which time passes, just highly unsure as to how you managed to get a c-relative one in the first place, as approaching c gives you less personal time per 'observational' time to accelerate in and other issues, with all the dilation of time, mass, length, etc, which means you're already spending your infinity of external time trying to reach 'c' (by which time the universe has probably conspired against you by putting something in your way or even ending in some cosmic way).  Without some special trick (alteration of your craft's overall inertial mass to zero, or whatever) it all ends up a little beyond the usual theoretical limits.

[Starver]

Intermission:
There's a theory that antimatter is regular matter traveling reverse in time. When it collides with regular matter and is "annihilated" that is actually the point that it reverses it's chronological direction.

Indeed, with the energy produced being required to be 'have been produced' (as viewed outside of time) to rebound the matter against to produce the backwards-in-time anti-matter counterpart which itself rebounds against energy input into a previous (from matter's timeline POV) initial matter/anti-matter creation event to become the matter counterpart in this latter (earlier) collision.

It's all quite interesting, though I think it sits in the same realm of theorising as the fact that a universe with three time and one space dimension is the ideal home for tachyons.

Another intermission:
A time machine that is actually being built relies on lasers bent into a loop. The light like this has the right properties to twist space-time, or so they say.

Probably similar to the "rapidly rotating masses" time machine.  Personally, I go for the wormhole version where you move one end around a lot and by the time you've finished, the stationary end might already have disgorged something you haven't yet put into the time-dilated end.  (Then you have to deal with whether whatever you arrange to go back in time to do something has already been back in time and done it...)

[Starver]

Funny to see an off-topic post in a thread formed from off-topic posts in another thread. 

Don't know if this speaks more about me than about forums in general, but I find it happens quite a lot.  I suspect it's not just my own rambling nature (and I wasn't responsible for the original off-topicness, anyway!) and just the sum-total of everyone's rambling, but I wouldn't be surprised to find I wasn't a major offender, from an external observer's viewpoint.  And those last three words almost bring things back to relevence.

[Neruz]

But magnetism does have an effect on light

Usually, no. Fixed magnetic fields have absolutely zero impact on light propagating through a vacuum and (even for rather large field strengths) negligible effect on light propagating through most materials.

There is one case in which magnetism can affect light, and that is in materials exhibiting the Faraday effect. In these materials, a magnetic field can change the way the charged particles (mainly electrons) respond to the light electromagnetic field. As a result, the polarization of the light rotates as the light propagates through the material. The direction of rotation depends on which way the field points.

[Neruz]

By the way; another fun way to use Black Holes for propulsion is to tow a small one behind you while using it's hawking radiation to push you forward. Apparantly if you get a near perfect reflection of the hawking radiation (basically a solar sail, but with hawking radiation instead of solar wind and black holes instead of stars) and you're using a ~1000 ton ship there's a particular size of smallish black hole (something like a million million tons, i don't remember the number) that will propel the ship to near light-speed just before the black hole evaporates. Apparantly the numbers line up eerily well

It is of course, entirely theoretical, probably rediculous and 100% off the record.

[DreamThorn]

What I am trying to get at with the divide by zero is that the universe divides by zero occasionally.  If we wish to do proper physics, we need a system that allows us to calculate the effects of such cases.

So, no matter how much you tell me of how dividing by zero doesn't work in real, imaginary, extended or hyperreal numbers, I will still be trying to do it.

So far, handling zero as if it is actually an unknown infinitesimal value has never failed me.  And the multiplicative inverse of such a zero would be a specific but unknown infinite value.  So 1/0 = 1*inf and inf/0 = inf^2 and 5/inf = 5*0.  I would like to know what you think of such a system.