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Sunday, March 6, 2011

Adapting Universal Constants...En route To A Single Law ?

Do these universal constants, intricate
values change over time ?
Gathering from the previous post, what could the consequence of the variations in the gravitational law depending upon the expansion of the universe and the dynamic nature of spacetime mean ? For one, this critical value of acceleration mentioned C^2/R,('C' speed of light, 'R' Scale of the universe), occurring wherever leads to phenomena which we generally wouldn't observe, an insight I gained from this could be the changing nature of constants. In other words the evolution of the entire universe, to how we see it today. The universe is undergoing an accelerated expansion. Therefore the connected and related value of C^2/R changes over a significantly immense period of time owing to the dynamic nature of ‘R’. Now this is interconnected to the orbital accelerations of the stars as shown in the previous post. The stars would fall out of orbit and the entire galaxy would
Rotation curve of a typical spiral galaxy:
predicted (A) and observed (B).
Do fundamental laws change ?
collapse in on itself, provided this value were to change even by a slight value. But this happens in a time scale quite colossal compared to even the time scale of creation of our solar system. Hence this leads to other consequences, if the value of the gravitational constant changes it being related to the expansion in spacetime, the changes should be reflected by the properties of matter lying within spacetime as gravitational constant is associated to matter. If matter’s properties are changing over this period of time, the remaining forces, laws, and constants governing their interaction, formation and appearance must also change with time. Everything hence in the world should be relative and is relative as seen in maximum cases. Thereby pointing to the fact that even these constants aren’t absolutely constant but just so within the conception of our (short) existence in the universe. This further leads to conclusions such as if the constants are changing overtime, the universe could have evolved into its present state like the evolution of humans from the single celled organism through constant adaption. The constants could have adjusted overtime to have attained the value they have as we observe them now. The value so attained so as to make sure the existence of the fundamental entity is not compromised. The entities of nature matter, forces, fields, would have corresponding to their environment provided by the dynamic spacetime fabric adjusted themselves accordingly to attain stability and gain the necessary values to sustain. Here I would like to mention the post the ‘Atomic life force’. From where I concluded that the very existence of the basic entity could itself signify a fundamental law.
An Evolving Universe ?

This could be one of the answers as to why the 20 constants in the Standard Model of Particle physics are fine tuned to these exact values, because they have  gradually adapted to these values overtime so as to work in perfect synchrony. Once they work in sync by adjusting to values to attain a universal balance, thereby not causing the universe to collapse into nothingness or spin out of control, they secure their existence in the universe. Now as expansion occurs slow stretching of the spacetime fabric’s fundamental entities to allow for the expansion might be occurring, this would lead to a point where sufficient stretching could reveal the true nature of spacetime. To probe  ‘empty space’ and reveal its true relationship with matter is an ongoing quest that is hot caught in the web of String physics which incidentally, leaves inquisitive ones dazed and puts up more questions than it answers ! 

Dark Matter – Dark Energy Congruence!

The Energy Density Pie 
A revelation that leads from performing the calculation C^2/R, wherein ‘C’ is the speed of light and ‘R’ is the entire universe’s scale is that it gives you an acceleration. As discussed in the previous posts, this acceleration magically falls in place of repulsive acceleration produced by the hypothesized Dark Energy, driving all galaxies apart. Thereby also giving it the nature of being the cosmological constant. 1.2 x 10^-8cm/sec^2 being the value of this acceleration.

Apart from that the universe is also hypothesized to contain Dark Matter a startling 23% of the energy density of the universe. The nature of which was also discussed in the previous posts. The discovery of the dark matter was a problem that was established by measuring the accelerations of the stars in the orbit about the center of its galaxy. The problem arises due the fact that given the measured acceleration astronomers could deduce from it, the distribution of the galaxy’s matter. In almost all cases a disagreement of calculation occurs with the matter observed experimentally.
3D map of the large-scale distribution of dark matter
What is happening here ? Two thing are possible. Either laws of gravitation as we know them are flawed and they’re breaking down at the scales of starts orbiting galaxies. Or there is some extra unobserved matter contributing to this anomaly in the acceleration of the star.
Another anomaly observed right outside our solar system was the Pioneer 10 , 11 spacecraft anomaly. There were accelerations that seemed to have popped out of nowhere affecting the trajectory of the spacecraft which was on its orbit around the sun. There is something common in all of these anomalies , an acceleration of unknown origin crawling out of nowhere leading to altered trajectories leading to results conflicting with those calculated with the known gravitational formulae. All of this could be attributed to Dark Matter.

Now let’s take a look at these stars that are actually orbiting around the galaxies center. The problems in confirming with calculated values do not occur for the stars in the orbits closer to the center of the galaxy, no problems there. The acceleration here is the one that is cause by the visible matter, so within this region the gravitational laws we know work fine. Go further out into exterior orbits and the problems start ascending. So where does the dividing line for this anomaly lie ? Where exactly do the results start opposing the ones we know. This line is determined by the ‘acceleration’ of the stars in the orbit around the center of the galaxy. What is this value of acceleration?
It’s the same as C^2/R, the critical value off acceleration responsible for the universe’s expansion (dark matter). This should surprise you out of your wits. Two completely unrelated phenomena are related at extreme scales. This was discovered in Mordelha Milgrom in the 1980’s. Also worth mentioning here is the variance in acceleration deduced for the Pioneer 10,11 spacecraft are roughly equal to this value.
The intriguing question is why does the nature of expansion on scales of the entire universe have anything to do with the trajectory of stars on orbits in any given galaxy? Universal expansion does not affect individual galaxies. The galaxies remain gravitationally bound by matter. Agreed the fact they are only moving apart from one another.  Hence the next post deals with the implications that this new found relation between Dark Matter, Energy and the extreme (lowest and highest) scales of the universe might have on the nature of physics.

Saturday, March 5, 2011

Breaking Down ‘Dark Energy’!

A source of light waves moving to the right.
frequency is higher on the right, and lower on the left.

Heard of the Doppler shift ?
Sure have, when the cars zooms past us sound undergoes a Doppler shift . Now imagine the car speeds away from us. Hence the successive wave like crests of sound that are emitted from the source car arrive later, further take more time to reach you (fixed observer),because the car constantly speeds away. Time taken for the sound crests to reach you increases, frequency decreases, the wave gets ‘REDSHIFTED’. Why Red ?. Red light has lower frequency than violet within the visible E.M spectrum hence the name. Observe this happens because the sound travels in a medium ‘air’ here. Therefore velocity of the observer and of the source are RELATIVE TO THE MEDIUM in which the waves are transmitted.

This simple phenomenon of ‘REDHIFT’ was also surprisingly universally observed for light during the 1910’s by Vesto Slipher for spiral galaxies and soon after for all galaxies. Implications weren’t clearly understood then. Ten years later Alexander Friedmann derived equations from general relativity showing that the universe might be expanding(or contracting cause of the dynamic nature of the spacetime) in contrast to the Static Universe model. Then keeping in light with the discoveries, Edwin Hubble empirically proved these observations of redshift from galaxies rushing away in all possible directions. Important to keep in mind is that it does not contradict Special Relativity or General relativity as for light waves or gravitational waves, the shift in wavelength necessarily compensates for the shift in frequency keeping the speeds of the waves constant ‘C’. Another essential fact is that there is no medium. When light is in observation the calculation WON’T INCLUDE THE MEDIUM of propagation as a reference point.   
The implications were extremely clear consequently, the known universe is indeed expanding. Every other galaxy is not just moving away but ACCELERATING away from our galaxy . Acceleration implies a force. The value of this repulsive acceleration is 1.2 x 10^-8cm/sec^2 . This force being the REPULSIVE kind. Force corresponds to energy over a period of time. According to the relativity theory, energy is equivalent to mass as a source of gravity. Which then according to general relativity means producing a positive curvature in space-time. So it curves the universe over the scale of ‘R’ equal to 10^27  cm^2  or 10 billion light years. Termed ‘DARK ENEGRY’ because of its undefined origins and little known dimensions of working and no known force carriers.  A very fascinating value, whose significance may well lie beyond our current understanding. This could possibly be assumed to be the famous cosmological constant that was hypothesized through the equations in General Relativity by Einstein. He proposed changes in G.R to accommodate its value, so that the repulsive force from the cosmological constant would balance out with the gravitational attraction to give a STATIC(never changing) model of the universe. That was the held belief for the past millennium, very hard to get out of, even Einstein’s insightful mind. 
Dark Energy's Significance in the Evolution of the Universe
(click to expand view)

Fascinating features worth mentioning involve, its density which appear exactly the same to all observers, with no preferred position, velocity, time, direction of motion extending uniformly throughout the universe. For positive values it causes the universe to expand, for negative causes it to contract and for a zero value causes it to remain static.
Energy as we know it now, is associated with matter. Dark Matter suggests exceedingly more. Its value is constant irrespective of any variance in the measurement circumstances. It has no known force carrying ‘BOSONS’ or massive ‘FERMIONS’. Majorly it comprises of 73% of the energy density of the universe still we’re unaware of its true nature. This should blow anyone away and it does accomplish that every time.
A few other facts that kick start some intuitive questions I’ve noticed are given here.
The cosmological constant now assumed to be dark energy extends over the scale of the entire universe of ‘R’. Perform a few related calculations at this scale, using universal constants to surprisingly get uncommon constants.
‘C’ the speed of light, perform R/C and you get time, which is roughly the present age of the universe.
Inverse this value and you get a frequency, probably the lowest possible achievable oscillation. Once per lifetime of the universe.
Next up perform C^2/R, gives acceleration, the value turns out to be the familiar value of the repulsive acceleration we know of, mentioned earlier
1.2 x 10^-8cm/sec^2. All of this gained simply out of operations using the speed of light. So many revelations from this data are yet waiting to be discovered.

One of the most exciting prospects that arise from experimental and theoretical observations, is the relation between the two very distinct phenomena ‘Dark Matter’ and ‘Dark Energy’. The features they hold in common might reveal completely new physics in the ‘R’ scales. This could trigger a re-formulation of many of the existing ground breaking laws in Physics. Even String Physics to that extent does not predict the existence of either Dark Matter or Dark Energy, while this does not mean String theory is wrong. You can always tweak it in ways that does accommodate ‘Dark Stuff’. This may also convey we’ve just seen the tip of the iceberg.
As we often see every few centuries. Precision of the experiments increase, we find anomalies that do not comply with existing data and suggest theories to overcome those anomalies which also predict further phenomena , if confirmed classify into established theories. Unraveling the usually overlooked and enlightening relationship between Dark Energy and Dark Matter would be done in the following posts.