Last December (’05), physicists held the 23rd Solvay Conference in Brussels, Belgium. Amongst the many topics covered in the conference was the subject matter of string theory. This theory combines the apparently irreconcilable domains of quantum physics and relativity. David Gross a Nobel Laureate made some startling statements about the state of physics including: “We don’t know what we are talking about” whilst referring to string theory as well as The state of physics today is like it was when we were mystified by radioactivity.
The Nobel Laureate is a heavyweight in this field having earned a prize for work on the strong nuclear force and he indicated that what is happening today is very similar to what happened at the 1911 Solvay meeting. Back then, radioactivity had recently been discovered and mass energy conservation was under assault because of its discovery. Quantum theory would be needed to solve these problems. Gross further commented that in 1911 “They were missing something absolutely fundamental,” as well as “we are missing perhaps something as profound as they were back then.”
Coming from a scientist with establishment credentials this is a damning statement about the state of current theoretical models and most notably string theory. This theoretical model is a means by which physicists replace the more commonly known particles of particle physics with one dimensional objects which are known as strings. These bizarre objects were first detected in 1968 through the insight and work of Gabriele Veneziano who was trying to comprehend the strong nuclear force.
Whilst meditating on the strong nuclear force Veneziano detected a similarity between the Euler Beta Function, named for the famed mathematician Leonhard Euler, and the strong force. Applying the aforementioned Beta Function to the strong force he was able to validate a direct correlation between the two. Interestingly enough, no one knew why Euler’s Beta worked so well in mapping the strong nuclear force data. A proposed solution to this dilemma would follow a few years later.
Almost two years later (1970), the scientists Nambu, Nielsen and Susskind provided a mathematical description which described the physical phenomena of why Euler’s Beta served as a graphical outline for the strong nuclear force. By modeling the strong nuclear forces as one dimensional strings they were able to show why it all seemed to work so well. However, several troubling inconsistencies were immediately seen on the horizon. The new theory had attached to it many implications that were in direct violation of empirical analyses. In other words, routine experimentation did not back up the new theory.
Needless to say, physicists romantic fascination with string theory ended almost as fast as it had begun only to be resuscitated a few years later by another ‘discovery.’ The worker of the miraculous salvation of the sweet dreams of modern physicists was known as the graviton. This elementary particle allegedly communicates gravitational forces throughout the universe.
The graviton is of course a ‘hypothetical’ particle that appears in what are known as quantum gravity systems. Unfortunately, the graviton has never ever been detected; it is as previously indicated a ‘mythical’ particle that fills the mind of the theorist with dreams of golden Nobel Prizes and perhaps his or her name on the periodic table of elements.
But back to the historical record. In 1974, the scientists Schwarz, Scherk and Yoneya reexamined strings so that the textures or patterns of strings and their associated vibrational properties were connected to the aforementioned ‘graviton.’ As a result of these investigations was born what is now called ‘bosonic string theory’ which is the ‘in vogue’ version of this theory. Having both open and closed strings as well as many new important problems which gave rise to unforeseen instabilities.
These problematical instabilities leading to many new difficulties which render the previous thinking as confused as we were when we started this discussion. Of course this all started from undetectable gravitons which arise from other theories equally untenable and inexplicable and so on. Thus was born string theory which was hoped would provide a complete picture of the basic fundamental principles of the universe.
Scientists had believed that once the shortcomings of particle physics had been left behind by the adoption of the exotic string theory, that a grand unified theory of everything would be an easily ascertainable goal. However, what they could not anticipate is that the theory that they hoped would produce a theory of everything would leave them more confused and frustrated than they were before they departed from particle physics.
The end result of string theory is that we know less and less and are becoming more and more confused. Of course, the argument could be made that further investigations will yield more relevant data whereby we will tweak the model to an eventual perfecting of our understanding of it. Or perhaps ‘We don’t know what we are talking about.’
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* http://facebook.com/ScienceReason … Albert Einstein’s Theory of Relativity (Chapter 1): Introduction.
The theory of relativity, or simply relativity, encompasses two theories of Albert Einstein: special relativity and general relativity. However, the word “relativity” is sometimes used in reference to Galilean invariance.
The term “theory of relativity” was coined by Max Planck in 1908 to emphasize how special relativity (and later, general relativity) uses the principle of relativity.
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Special relativity is a theory of the structure of spacetime. It was introduced in Albert Einstein’s 1905 paper “On the Electrodynamics of Moving Bodies” (for the contributions of many other physicists see History of special relativity). Special relativity is based on two postulates which are contradictory in classical mechanics:
1. The laws of physics are the same for all observers in uniform motion relative to one another (principle of relativity),
2. The speed of light in a vacuum is the same for all observers, regardless of their relative motion or of the motion of the source of the light.
The resultant theory agrees with experiment better than classical mechanics, e.g. in the Michelson-Morley experiment that supports postulate 2, but also has many surprising consequences. Some of these are:
• Relativity of simultaneity: Two events, simultaneous for one observer, may not be simultaneous for another observer if the observers are in relative motion.
• Time dilation: Moving clocks are measured to tick more slowly than an observer’s “stationary” clock.
• Length contraction: Objects are measured to be shortened in the direction that they are moving with respect to the observer.
• Mass-energy equivalence: E = mc2, energy and mass are equivalent and transmutable.
• Maximum speed is finite: No physical object or message or field line can travel faster than light.
The defining feature of special relativity is the replacement of the Galilean transformations of classical mechanics by the Lorentz transformations. (See Maxwell’s equations of electromagnetism and introduction to special relativity).
General relativity is a theory of gravitation developed by Einstein in the years 1907–1915. The development of general relativity began with the equivalence principle, under which the states of accelerated motion and being at rest in a gravitational field (for example when standing on the surface of the Earth) are physically identical. The upshot of this is that free fall is inertial motion; an object in free fall is falling because that is how objects move when there is no force being exerted on them, instead of this being due to the force of gravity as is the case in classical mechanics.
This is incompatible with classical mechanics and special relativity because in those theories inertially moving objects cannot accelerate with respect to each other, but objects in free fall do so. To resolve this difficulty Einstein first proposed that spacetime is curved. In 1915, he devised the Einstein field equations which relate the curvature of spacetime with the mass, energy, and momentum within it.
Some of the consequences of general relativity are:
• Time goes slower in higher gravitational fields. This is called gravitational time dilation.
• Orbits precess in a way unexpected in Newton’s theory of gravity. (This has been observed in the orbit of Mercury and in binary pulsars).
• Rays of light bend in the presence of a gravitational field.
• Frame-dragging, in which a rotating mass “drags along” the space time around it.
• The Universe is expanding, and the far parts of it are moving away from us faster than the speed of light.
Technically, general relativity is a metric theory of gravitation whose defining feature is its use of the Einstein field equations. The solutions of the field equations are metric tensors which define the topology of the spacetime and how objects move inertially.
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Einstein’s Theory Of Relativity Made Easy