The Speed of Light (and Gravity?)

Within Relativity Theory, if there is anything unintuitive it is the fact that in the entire Universe, it is the speed of light (and gravity?) alone that is absolute or fixed, not something like space being absolute or time being absolute. It’s unintuitive in that all the other not-light bits and pieces that are in motion can be added or subtracted. The lone exception to that universal rule that velocities can be mathematically combined is the speed of light (and gravity?).

Repeat for emphasis: the anomaly here is that in any other scenario, anything that is not-light and in motion, velocities can be added and subtracted. Repeat again: with that one speed of light exception, velocities may be added or subtracted. If you are on a treadmill that’s moving left at 5 MPH, and you’re on it walking to the right at 5 MPH, to an external observer you are waking yet standing still. You’re much more likely to hit a home run if the wind is blowing towards the outfield fences; planes fly faster with a tailwind than with a headwind; you swim in the river faster going with the flow than against the current. If you are in a train that is moving at say 100 km/hour and you throw a ball at 10 km/hour in the direction at which the train is moving, to an observer outside the train, your ball is traveling at 110 km/hour. If you throw the ball towards the rear of the train, an outside observer will measure the ball as moving at 90 km/hour. If on the other hand, you shine a flashlight in the train, an outside observer will see the velocity of the resulting light beam moving at the speed of light – not the speed of light PLUS the velocity of the train, or the speed of light MINUS the velocity of the train, but at the speed of light! That’s nuts, but it’s scientifically nuts and been proven again and again in any experiment you care to devise. I have no issue with experimentally verified results. That doesn’t mean I don’t have issues with the anomaly.

The velocity of light is a constant to an external observer no matter what. Why that should be no one knows, but it is so. However, my take on this can of worms, which as a consequence requires somewhat counter-intuitively that both time and length have to be flexible, is one should always be a bit suspect when it comes to the lone ranger, the lone ranger being the exception to the rule*. I don’t tend to like exceptions to the rule. There’s something weird afoot here. Mother Nature is trying to tell us something we haven’t figured out yet.

All that said, the speed of light isn’t really a constant if you take into consideration the differing mediums that light can travel through. However, the speed of light is probably also a constant within whatever other medium it happens to be in. The speed of light in air at STP (standard temperature and pressure) is less than the speed of light in the relative vacuum of outer space; even less traveling through pure water and less again traveling through clear glass. One would presume that just as the speed of light in space is constant for observers regardless if they are traveling in a high velocity spaceship or as an astronaut ‘stationary’ on the International Space Station, the speed of light in water sould be a constant for the crew in a submarine that’s underway thus in motion or a diver standing on the seabed.  

That makes me sort of wonder, theoretically, if you could get an underwater submarine to go faster than the speed of light in water (or an aircraft to outpace the speed of light in air), though in either case that would be less than the speed of light in a vacuum, could you then claim, albeit with qualifiers (in water; in air), that you actually traveled faster than the speed of light, if only for the bragging rights? 

Apart from light (photons), presumably gravity, or gravity-waves, also propagate at the speed of light and thus a gravity-wave would have a constant speed regardless of any frame of reference for any observer. But I also presume that necessitates finding the hypothetical graviton particle (to mirror the photon) and that, for the moment, resides in the unknown basket.

That brings up yet another puzzlement. Is gravity just geometry as per General Relativity or is gravity a force transmitted by a force particle, the theoretical graviton, and thus more akin to electromagnetism’s photons (infinite extension; obeys the inverse square relationship) apart from lacking EM’s negative counterpoint – in the case of gravity, that’s antigravity.

Speaking of gravity (gravitons) and light (photons), if gravity can have an effect on light (i.e. – the gravitational lens), then it should be a two-way street and light should be able to have an observable affect on gravity, but I can’t recall ever reading about that aspect of the relationship. 

As per the speed of light being medium dependent; one speed in a vacuum, another in water, well that makes for an interesting question when considering gravity. If a gravity-wave is approaching Earth, will it have one constant velocity in the vacuum of space for all observers, then a differing velocity as it passes through our atmosphere, then another value as it passes through the ocean and yet others as it hits the various density layers inside the planet?    

As is often the case, there tends to be more questions than answers!

*Not that the differing rules for the speed of light vis-à-vis other not-light velocities is the only exception to the rule in modern physics. Quantum tunneling is one of those exceptions to the rule of causality. With respect to the standard model of cosmology and the Big Bang, first there was nothing; then there was something. That means the Big Bang event created both matter and energy out of less than thin air. That’s also a free lunch and one of those exceptions to the rule of physical law usually expressed as the conservation of matter and energy. All these exceptions to the norm suggest that some of the final chapters in modern physics haven’t yet been written.



A Multiverse of Braneworlds: Part Two

For millennia, New Age devotees have related observations of nebulous exotic entities from apparently alternative realities like Parallel Universes that have made a crossover into our reality. Rational people suggest that’s just so much bovine fertilizer. Or is it? Perhaps theoretical physics and String Theory might just support such an exotic scenario, the scenario of the Braneworld.  

Continued from yesterday’s blog…

Anomalies aside, another 3-Braneworld could be, well millimeters away from our 3-Braneworld along with their ‘shadow entities’ or ‘higher beings’ or ‘aliens’ and we’d never know it except through their gravitational contribution, what we call ‘Dark Matter’ which, because it doesn’t actually exist  in our own 3-Baneworld universe, can never have its identity ‘discovered’ in our labs or high-energy particle accelerators like CERN’s Large Hadron Collider.

It should be pointed out that even though two 3-Braneworlds could be millimeters apart, they are not intersecting, just as your home and your next door neighbor’s home don’t overlap. 

So another question obviously arises. If our 3-Braneworld in that five dimensional space-time Bulk is in extremely close proximity to another 3-Braneworld also in that five dimensional space-time Bulk, and there’s gravity twixt them and us, well, what happens when two 3-Braneworlds collide in the higher dimensional Bulk?

If two 3-Braneworlds are attached by sharing gravity via those open strings, then they in fact can collide. It’s our Big Bang event of 13.7 billion years ago explained. The Big Bang was just a massive supply of kinetic energy supplied at one location; one set of coordinates, caused by our 3-Braneworld impacting another 3-Braneworld at that one specific point. The two 3-Braneworlds then rebounded, but of course could collide again at a later (unpredictable) date. It’s an interesting variation on the concept of a Cyclic Universe.

The standard 3-Braneworld model likens them to very flat and thin rubbery membrane sheets parallel to each other, sort of like thin LP albums cheek-by-jowl with only tiny separations between them on a shelf. They can approach (under gravity), collide (not everywhere at once as they are not 100% mirror smooth due to random quantum fluctuations if nothing else) then rebound. I think that’s imposing a rather artificial and rigid set of conditions though I gather if you crunch the numbers two membrane thin and parallel 3-Braneworlds are the most likely and stable geometric configuration you can get (but I still think that’s unsatisfactory). Normally when you think of something like the Universe, and something that’s expanding, you think of round things – not flattish membrane sheets. So how about an elastic balloon-ball analogy?

Say we have two 3-D elastic balloon-balls in 4-D ‘space’ (I think they actually call this hyperspace as well as the Bulk) or a five dimensional space-time realm. There could in reality be a dozen 3-Braneworld balloon-balls all in close proximity, but two’s enough for now to illustrate things. These 3-D elastic balloon-balls in collision can expand and contract and ripple, though they remain tethered together by those spring-like interbrane forces (those open string gravitons).

Each 3-Braneworld balloon-ball has a mix of radiation, matter and Dark Energy which dominates that balloon-ball in turn as the 3-Braneworld evolves cyclically by experiencing a collision, the Big Bang; an expansion; dilution of each component element in turn – otherwise called entropy; cooling; and contraction back to its original state ready for another collision and Big Bang. That term entropy is nothing more than the concept that order tends towards disorder, or in other words, all that original high ordered radiation, matter and Dark Energy becomes more disordered and all ends up ultimately as a uniform but very dilute ‘soup’ until the next injection of kinetic energy – the next collision and Big Bang in an endless cycle.

So, the story thus far: Two 3-Braneworld balloon-balls in higher dimensional space-time (the Bulk, which isn’t a static ‘observer’ but an active participant in these events), slowly, ever so slowly start to gravitate towards each other, slowing but surely picking up speed over time. Okay, so they approach each other under their joint mutual gravitational attraction. They hit (that’s our Big Bang); they ring or reverberate like a bell; they compress and each balloon-ball heats up die to that initial compression and expands; the two balloon-balls rebound but quickly slow, stop and set the evolving conditions in each balloon-ball recycle back for a repeat performance.

Another way of putting that evolution is that the kinetic energy of motion resulting in the Big Bang event at time and point of collision was converted to radiation, matter and Dark Energy which then dilutes over time as the 3-Braneworld expands, finally cools, slows down, contracts back to it’s original balloon-ball configuration.

Those extra-dimensional spring-like dynamics keeps the 3-Braneworlds apart but tethered though both are individually expanding or contracting or rippling and both are on the rebound from the other. When things settle down, and maximum entropy rules the roost, they can come together again still connected to its neighboring counterpart by those open graviton strings.

Fly-In-The-Ointment #1: Even if other entities are just millimeters away in their 3-Brane Universe, they are as separated from us by the five-dimensional space-time Bulk as we are from them. How can they use gravity to get from their 3-Braneworld to its next door neighbor 3-Braneworld (that’s us) through higher dimensional space-time? One can’t just hike across gravity like it was a bridge. There’s gravity between the Earth and the Moon but you can’t walk-the-walk between the two.

How then does an otherworld, a 3-Braneworld ET or the ‘higher beings’ that exist there get to our 3-Braneworld and then appear as those New Age ‘shadow beings’ from those mystic Never-Never Lands they like to go on, and on, and on about? Well, about the only viable scenario I can think of is excessive gravity translates into Black Holes which can, in theory, translate into Wormholes (for lack of a better word or concept) and Wormholes can be used, in theory, as a transit system. On the plus side, entities intelligent enough to manipulate gravity to create a wormhole transit system with entrance and exit portals will have no need of intergalactic or interstellar spaceships and million year journeys.

Fly-In-The-Ointment #2: String Theory, Branes (“p” or otherwise), the Bulk (or hyperspace), etc. well it’s all just pure (and highly technical) mathematical theory. There’s not one shred of experimental evidence; there’s not one single run on the board that Strings and Branes exist. Till some theoretical physicist turns experimental physicist and hits a homerun, well I’m afraid all of the above will have to reside in New Age La-La Land, however fascinating the scenarios are.

A Multiverse of Braneworlds: Part One

For millennia, New Age devotees have related observations of nebulous exotic entities from apparently alternative realities like Parallel Universes that have made a crossover into our reality. Rational people suggest that’s just so much bovine fertilizer. Or is it? Perhaps theoretical physics and String Theory might just support such an exotic scenario, the scenario of the Braneworld.  

Question: Might 3-Braneworlds equal Parallel Universes (or in mystic-speak Astral Planes; Alternative Realities; Spirit Worlds; Parallel Realities; Higher Planes of Existence; Higher Dimensions; Portals in Space-time, as well as a host of related New Age claptrap phrases that non-New Age squares indeed call claptrap) from which come ‘higher beings’, ‘astral entities’, our ‘enlightened space brothers’ or even plain ordinary everyday run-of-the-mill aliens.  

You cannot have nebulous otherworldly beings, or alternate reality entities, without having an alternative place or reality or an otherworld(s) from which they come from visiting from and call home. Higher planes of reality and associated phrases have been called so much poppycock and confined to the rubbish bin, but perhaps prematurely.

Well, String Theory comes to the rescue, if not for the benefit of New Age gurus, then for cosmologists and theoretical physicists. But perhaps we can kill the two birds with the one stone as it were.

It all starts with String Theory. Now you probably think of the elementary particles, if you think of them at all, as very tiny little billiard balls. However, some bright sparks decades ago came up with an alternative. Instead of a zoo full of different types of little billiard balls, there were tiny vibrating strings. How they vibrated determined what kind of elementary particle it was – one good vibration/second might be an electron; two good vibrations/second a positron; three good vibrations/second equate to a neutrino, etc.

Strings could either be open (like an ordinary piece of string) or closed loops like a circle or ellipse; somewhat like a doughnut.

Now these strings are one-dimensional. But there can be two-dimensional Stringy objects, called Branes, short for Membranes. In fact, Branes became the generic name for all structures in String Theory, usually identified as p-Branes (weak pun) where the “p” stood for the number of spatial dimensions. So a 1-Brane was a string; a 2-Brane was a membrane; a 3-Brane was akin to our own version of reality. A 3-Brane is commonly referred to as a 3-Braneworld.

Oh, there’s a catch. In order for String Theory to theoretically work, there has to be extra dimensions (I can hear New Age mystics cheering now), in fact nine spatial dimensions all up, plus the one dimension we call time. So, in fact you could go all the way up to a 9-Brane. Again all p-Branes have an extra time dimension as well tagged on. All up, that’s six more spatial dimensions than we are comfortable with, but they tend to be out-of-sight and out-of-mind. Most extra dimensions are extremely tiny and curled up and hiding in-between the bits and pieces, the flotsam and jetsam of the quantum realm. But one extra dimension could be extremely large indeed providing the space all else, like 3-Braneworlds, is housed in.

Now 3-Braneworlds have to exist in higher dimensional space, like a 4-Brane which we can’t traverse. It’s just akin to how a fridge magnet is ‘trapped’ on a 2-D fridge surface (a 2-Brane plus extra time dimension) yet resides within a 3-D (3-Brane plus additional time dimension) space. Or, to use another analogy, a 2-D shower curtain hangs in 3-D space but the water droplets are confined to the 2-D shower curtain surface. We’re confined to a 3-D universe ‘surface’ (3-Braneworld plus one time dimension) but that resides in a 4-D (4-Brane plus one time dimension) volume. To cut to the chase, lets just call that what our spatial 3-Braneworld universe reside in a realm of five space-time dimensions. That realm has been given a name – it’s called the Bulk. Why it is called the Bulk I have no idea, but that’s what it is named.

I’ve notched the Bulk up to being a five dimensional space-time (out of a possible ten), but it could just as easily I guess be the tenth space-time dimension (9 spatial and one of time). It doesn’t really matter since we can’t directly see it, taste it, touch it, hear it or smell it, be it a 4-Brane or a 9-Brane. But regardless, the absolute key point is that gravity can connect 3-Braneworlds via the Bulk whether the Bulk has a 4-Brane, 5-Brane, 6-Brane, 7-Brane, 8-Brane or 9-Brane spatial dimensionality.

So much for the background theory: now, the interesting bit is what if our universe were in fact, in reality, really a 3-Braneworld (plus a single dimension of time) residing in 4-Brane spatial volume, or the equivalent, a five space-time dimensionality (the Bulk). What if in fact there were other 3-Braneworlds (each with a time dimension) residing in that same 4-Brane (plus time dimension) volume of five dimensional space-time (the Bulk). Because of that residing (or hiding) in a higher spatial dimension, two 3-Braneworlds could exist within millimeters of each other, unseen, separated by the Bulk. Why unseen? It’s back to those tiny open and closed strings and where they call home.

Closed strings are confined to our own 3-D or 3-Braneworld universe (like water droplets on that shower curtain) where they appear as those elementary particles that are associated with electromagnetism like photons and electrons, as well as those particles part and parcel to the strong and weak nuclear forces. These three forces are the quantum forces that rule our roost. If closed strings are the case for neighboring 3-Braneworlds, then we can’t see them because their electromagnetic (light) particles, photons, are forever confined and trapped to that 3-Braneworld and never reach us. Other 3-Braneworlds are invisible to us. That leaves the fourth force, the non-quantum force, gravity.

Open strings are the force particles of gravity, called gravitons. Open strings can exist with one string end attached to our 3-Braneworld, the other string end to an alien 3-Braneworld. Open strings, in other words, could cross the Bulk from our 3-Braneworld to another 3-Braneworld and be attached to both. In other words, gravity is our best bet means of detecting other nearby 3-Braneworlds. But you can’t see gravity, so our neighboring 3-Braneworld is for all practical purposes is still invisible to us. However, you can ‘see’ the effects that gravity has on objects you can see. You can’t see the gravity that controls the flight of a baseball, but you can see the effect of gravity on the baseball.

Postulating a nearby 3-Braneworld explains a trilogy of puzzlements. One is Dark Energy, one is Dark Matter; the other third is why gravity is so weak relative to the other three fundamental quantum forces (electromagnetism; weak and strong nuclear)

The Mystery of Dark Energy: If two 3-Braneworlds are in close proximity, attached by gravity, then they could have a close encounter of the ka-boom kind. We might term that ka-boom a ‘Big Bang’. If the Big Bang was an actual collision between two 3-Braneworlds (known as the Ekpyrotic Universe scenario), causing a ripple and expansion effect, then Dark Energy is that left over residual oomph, the continuing shock wave of the Big Bang which comes to the fore and dominates the Universe when the initial radiation dominated epoch and the following matter dominated epoch begin to thin out or dilute as the Universe expanded. In this scenario however, we have to have Dark Energy eventually thin out, dissipate and fade away too.

The Mystery of Dark Matter: In order to explain various rotational anomalies of the galaxy, ours and others, additional but unseen matter with associated gravity has got to exist – it’s either that or we have to drastically revise the laws of gravity as we currently understand them and no scientist is wiling to tilt at that windmill. Unfortunately, this postulated additional matter isn’t akin to normal matter which you can detect because you can see it. We can’t see this additional matter which is postulated, indeed nearly required, to exist. That’s why it is called ‘Dark Matter’, though a better term might be ‘invisible matter’. However, if a nearby 3-Braneworld universe shared its gravity with us, via those open graviton strings that transverse the Bulk, well that explains the ‘need for extra gravity’ to explain rotational anomalies and thus eliminates the need for the theoretical un-matter-like ‘Dark Matter’.

The Mystery of Weak Gravity: Gravity is the 98-pound weakling force relative to the trio of Charles Atlas quantum forces. Why has always been a total mystery that theoretical physicists have had to deal with. Open (gravity) strings in the Bulk explain why. Closed strings are confined to our own 3-Braneworld. We feel their full strength. However, our open string gravitons aren’t confined to our 3-Braneworld. Our gravity is diluted by spreading out into and throughout the Bulk and also attaching to other 3-Braneworlds. That’s why it’s the 98-pound weakling.

Another mystery is to answer the question, if our 3-Brane universe is expanding, what is it expanding into? Well, it’s expanding into that five space-time dimensional Bulk. 

To be continued…