Posts tagged ‘quantum theory’

October 7th, 2011

Neutrinos Faster Than Light or Extra Dimensions?

by Max Andrews

Source: CERN Press

By now we’ve all heard of the news coming out of CERN and OPERA on 23 September that the Italian accelerator, OPERA, measured neutrinos traveling faster than the speed of light.  I didn’t comment on the finding right away because I wanted to do some research on the claims and on what exactly happened.  So here are my two-cents.

So, what exactly is a neutrino?  A neutrino is a fundamental particle and crucial for the standard model of particle physics.  The neutrino comes tin three types: [associated with] the electron, muon, and tauon, which are fermions and part of leptons.  The have no electric charge and interact only via the weak nuclear force (see the Oxford Companion to Cosmology for more on this).  These particle are incredibly difficult to detect and pass through our bodies all the time (this is a nice little Italian cartoon that has an excellent depiction of neutrinos).

So, what happened?  CERN sent the neutrinos 730lm to the Italian accelerator OPERA.  The journey only took 2.43 milliseconds and the scientists timed it to within 10 nanoseconds. (A millisecond is a thousandth of a second, 1/1,000s and a nanosecond is a billionth of a second, 1/1,000,000,000s).  The neutrinos arrived 60 nanoseconds earlier than they would have if they were traveling at the speed of light (c = 299,792,458 m/s). There are three options of what could have happened.

  1. Option One.  The experiment was in error and the calculations are simply incorrect.
  2. Option Two.  The speed of light is not the cosmic speed limit and there must be slight adjustments for relativity theory.
  3. Option Three.  The neutrinos took a shortcut through extra dimensions.

Option One: Experimental Error.  The OPERA team spent three years trying to calculate and find every error they could possibly find.  The neutrinos are produced by colliding protons into a graphite target to produce pions and travel a 1km tunnel and decay to produce neutrinos.  Electronic delays in the timing system that records when protons arrive at the graphite target introduce uncertainty.  However, this margin of error is 5 nanoseconds. Where the pions decay is also unknown, which produces an error of 0.2 ns.  Measuring the distance is also difficult because the OPERA lab in Gran Sasso is inside of a mountain, which is undetectable to GPS.  However, the distance can still be calculated to within 20 cm.  The error is 0.67 ns.  With the other errors taken into consideration, the total error bar is 7.4 ns.  Remember, if experimental error is going to be the prevalent option the errors have to account for 60 nanoseconds.

Option Two: Adjusting Relativity.  If it really is the case that the neutrinos did travel faster than the speed of light then Einstein isn’t completely thrown to the curb.  There must be a theory that will account for this that will be closer to the truth.  This has historical precedence.  Newtonian physics were thought to explain the universe until Einstein came around with the concept of relativity.  Newton wasn’t necessarily wrong, Einstein just provided a more accurate theory.  If neutrinos can travel faster than c then we need another Einsteinian discovery.  Not that big of deal.

Option Three: Extra Dimensions.  It may be the case that the neutrinos, when travel with an incredible amount of energy, travel through the smaller curled up dimensions.  Consider the neutrinos traveling into the fourth dimension, this would actually make the distance much shorter.  Hopefully this illustration will help.  Take a piece of paper and draw a straight line across the paper.  Label one end of the line A and the other B.  This line is one-dimensional.  Take the paper and fold it so it creates an upward arch.  Now, if you were to travel from A to B by going through the paper instead of curving around the outside of the paper then the distance would be shorter.  This may, perhaps, be what happened to the neutrinos. (For more information on the discovery see New Scientist No. 2832, October 1-7 2011).

I tend to lean more towards option three, that the neutrinos passed through the smaller extra dimensions.  This would be an incredible development that would contribute to and, possibly, confirm a prediction of string theory.  Part of this may be wishful thinking on my part but this may potentially be an incredible empirical find that would confirm the mathematics.  Now, what about further philosophical or theological implications?  I don’t think this has too much of an impact on philosophy or theology that hasn’t already been addressed concerning the philosophy of science or of scientific theology.  For more on these implications see “The Relationship Between Science and Philosophy,” “Einstein, the Big Bang, and Natural Theology,” “Einstein on Free Will,” and “Einstein’s Impact on the Epistemic Method.”

August 11th, 2011

Einstein on Free Will

by Max Andrews

After the First World War Einstein made contributions to the development of quantum theory, including Bose-Einstein statistics and the basics of stimulated emission of radiation from atoms (which was later used to develop lasers).  He gave the nod of approval that led to the rapid acceptance of Louis de Broglie’s ideas about matter waves but he never came to terms with the Copenhagen interpretation of quantum mechanics.[1] The Copenhagen has become the more popular and standard interpretation.[2]

According to the Heisenberg Principle, the moment at which a measurement takes place is the moment at which the randomness lying at the heart of quantum reality expresses itself.[3]  Up to that point, everything is fine.  Amplitudes change in a completely predictable, and more importantly, calculable way.  The observer changes the state of what is being observed.  Outcomes can be predicted according to governing probabilities, but the actual outcome cannot be known in advance.[4]

This was something Einstein could not live with.  Einstein, as a determinist, felt that the world is a structured and rigid web where effects follows cause and all things should be predictable, given the right information.  Einstein acknowledged that quantum theory works but he did not like the philosophy behind it.  If whether or not, for example, Niels Bohr, Einstein’s quantum physics counterpart, were to throw a book across the room Einstein would be able to predict the outcome of Bohr’s “choice.” Einstein would of course say that choice is the wrong word to use; rather, the brain is a complex machine with cogs whirring round to produce a predictable action.  The basis of Einstein’s view was a philosophical conviction that the world did not include random events:  an objection summed up in Einstein’s widely quoted saying, “God does not play dice.”[5]  Bohr is reported to have responded to Einstein with the witty reply, “Don’t tell God what to do.”

Strict [or hard] determinism may be the only way to avoid the implication from quantum mechanics and experiments such as the delayed choice experiment.[6]  This experiment suggests that quantum communications occur instantaneously across any distance, or even travel backwards in time.[7]  The determinist is not yet defeated, quantum mechanics comes with a state of collapse and that seems to be linked to measurement.  Whatever measurements are, they are very specific situations and probably linked to what happens when a particle bumps into a measuring device.[8]

Einstein played a prominent role in the early development of quantum mechanics, particular in his philosophical approach to it.  How one interprets quantum mechanics will shape the answer to the question of determinism and free will.  Empirical testing does not seem to be enough to provide a satisfactory answer; rather, it how the data is interpreted.  Einstein’s approach to the rejection of genuine random events has been an influence of the contemporary debate.  It has been argued that Einstein’s determinism is correct, but it may be a mistake for him to base it on random events.  Randomness is not sufficient for determinism to be true; a lack of causality would be sufficient.  Even with the delayed choice experiment there seems to be a lack of causality, if anything it would be backwards causality.  The free will proponent must be careful not to appeal to any ignorance for a lack of explanation of such quantum events.  Einstein’s reason for determinism (randomness) does nothing to advance his case.  If anything, quantum experiments such as the delayed choice experiment only show that there is randomness in the world, not that there is purposeful, free agency.  All quantum mechanics entails is that there are random events in the brain (or whatever) that yield unpredictable behavior, which the agent is not responsible.[9]  Thus, it seems to be the case that Einstein’s philosophy of determinism has persevered.[10]

[1] Kenneth William Ford, The Quantum World: Quantum Physics for Everyone (Cambridge, MA: Harvard University Press, 2004), 117.

[2] At this time there are at least ten regularly cited interpretations of quantum physics varying in interpretation of wave collapse, determinacy/indeterminacy, superpositions, and Schrödinger’s equations.

[3]  The equation: (change in x multiplied by the change in px is greater than or equal to half of Planck’s constant). For a given state, the smaller the range of probable x values involved in a position expansion, the larger the range of probable px values involved in a momentum expansion, and vice versa.  The key to the expression is the greater than or equal to because it places a limit on how precise the two measurements can be.  The principle is relating and for the same state ( signifies change, h, h-bar, is the Planck constant).  Heisenberg’s target was causality. The Copenhagen interpretation adopted this principle.  Jonathan Allday, Quantum Reality: Theory and Philosophy (Boca Raton, FL: CRC Press, 2009), 247-248.

[4] Jonathan Allday, Quantum Reality: Theory and Philosophy (Boca Raton, FL: CRC Press, 2009), 100-101.

[5] Allday, 101.

[6] If photons are fired through the experiment one at a time (firing photons at a wall with two holes and a photon detector on the other side of the holes), they will build up an interference patter on the other side, as if they had gone through both holes at once and interfered with themselves.  If the experiment is set up so that detectors monitor which hole the photo goes through, the photon is indeed observed to be going through only one hole, and there is no interference pattern.  If a detector is set up not at the holes but intermediate between the two holes and the back wall detector screen then it may be possible to see which route a particular photon took after it had passed the two holes before it arrived at the screen.  Quantum theory says that if we choose to turn this new detector off and not look at the photons, they will form an interference pattern.  But if we look at the photons to see which hole they went through, even if we look after they have gone through the hole, there will be no interference pattern.  The delayed choice comes into the story because we can make the decision whether or not too look at the photon after the photon has already passed through the hole[s].  The decision made seems to determine how the photon behaved at the time it was passing though the hole a tiny fraction of a second in the past.  It seems as though the photons have some precognition about how the set-up of the experiment will be before it sets out on its journey.  This has also provided credence to the metaphysical concept of backwards causation.  John R. Gribbin, Mary Gribbin, and Jonathan Gribbin (Q Is for Quantum: Particle Physics from A-Z. London: Weidenfeld & Nicolson, 1998), 102-103.

[7] This is most notably accepted by the transactional interpretation of quantum mechanics. Gribbin, 104.

[8] Allday, 102.

[9] Predictability may be equivalent to randomness, not a lack of causality.  Louis Pojman, Philosophy: The Pursuit of Wisdom (Boston, MA: Wadsworth, 2006), 229-230.

[10] Recalling Einstein’s epistemic method, he based all of his philosophy and work on the ontological status of the universe.  He did not seem to indicate an immateriality to the mind.  Einstein’s influence is limited only to the physical aspect for the substance dualist.  Here is where the substance dualist and the scientific theologian must resume the dialogue.