7 Replies Latest reply on Aug 14, 2014 7:40 AM by Mitsuru Yamada

    Is a collapse of wave function real?

    Mitsuru Yamada

      When I was young, I was taught in the university class as the usual textbook says; if we measure the position of a quantum mechanical particle, then its wave function shrinks to a Dirac' delta function of positional variable.


      But in the recent book of John Gribbin, it is written that; "the collapse of wave function is a device introduced by Niels Bohr without evidence whatsoever."  And the book further introduces other theory that can avoid the necessity of introducing the collapse of wave function.  It is "transaction interaction"proposed by John Cramer.


      Which is true at all?  Is there surelly the collapse of the wave function or not?

      Please someone tell me the truth.


      Old poor stray sheep

        • Re: Is a collapse of wave function real?
          Walter Freeman

          Dear Old, Poor, Stray Sheep  (aka Mitsuru Yamada),


          Many physicists have long been concerned with this question of quantum wave function collapse, beginning, of course, with Niels Bohr, himself.  It turns out that a landmark paper (Ph.D. thesis actually) was written on the subject by Hugh Everett III at Princeton in 1957.  Everett assumed that the wave function did not collapse upon observation and proceeded from there.


          What happened next is quite the story, but one which I am in no way qualified to tell.   Like many people who are ahead of their time, Everett's personal story is a tragic one.


          The wave function does not collapse as per the "Copenhagen interpretation," but this leads to a bit quantum weirdness that will certainly boggle most minds.  Hint:  multiverses are involved without number.  Yet, it turns out that the current study of cosmology especially results from the increasingly measured fine structure of the cosmic microwave background as well as a growing school of thought (still controversial) is consistent with a multiple universe view.


          If you are up for a bit of mind boggling, as it were, may I recommend to you a new book by MIT professor and physicist, Max Tegmark, "Our Mathematical Universe:  My Quest for the Ultimate Nature of Reality," Alfred A. Knopf, New York, 2014? 


          In this book, you will be taken through arguments as to whether the Schrodinger wave function collapses or not.  Furthermore, you can use the book as a spring board into the literature on the subject in the "Suggestions for Further Reading" section.  Tegmark also includes numerous references in the text to on-line sources for supporting papers. 


          Prof. Tegmark broaches and then gets into the subject of quantum wave collapse in some depth (but no math whatsoever) in Chapter 8, "The Level III Multiverse," and thence for the remainder of the book.  However, to really follow the arguments and as a bit of a refresher, I advise reading the first seven chapters as well. 


          This book is very well written and is anything but dry.  Max Tegmark writes from a candid and personal level so that the reader is drawn into his world and world view (or universe view) in a charming way.  He succeeded in sharing his fascination with physics and as the subtitle suggests, "The Ultimate Nature of Reality," with me.  So I say that this is an exciting and interesting read.  I highly recommend the book. 


          I rather suspect that the word "mathematical" in the title will be off-putting to many, who otherwise would enjoy this book.  Too bad, for there is no math in the book. Just the concepts behind the mathematics and the interpretations that the math suggests.


          By the way, if after digesting the prose of the book and maybe dipping into the technical literature referenced therein, if you still have questions or concerns, Max Tegmark is easy enough to contact directly.  You can find his email address from the MIT faculty list on-line.


          Just don't ask me!


          Good luck and welcome to the Multiverse!

            • Re: Is a collapse of wave function real?
              Mitsuru Yamada

              Thank you for your response.

              Your book looks very interesting.

              I will try to obtain it.


              Though you wrote that Hugh Everett III was tragic since his theory was not accepted by the physicists in his time, but I read in other book that he later had become a multi-millionair.  So Hugh Everett became very happy finally in his life. Didn't he?


              Thank you again.

                • Re: Is a collapse of wave function real?
                  Walter Freeman

                  Only if you consider that Dr. Everett never practiced physics, was alcoholic, was a chain smoker, and was obese when he died suddenly from a heart attack at the age of 51 in 1982. 


                  He was bitter that his work was not recognized nor accepted and that his science career was effectively stunted from the beginning.  In an ill-fated meeting with Niels Bohr himself, Everett received the ultimate rejection and put down for his heresy.  You can find more about Hugh Everett in the Wikipedia article on him.  Nonetheless, he was successful in working in the defense industry and in that regard was financially secure.


                  Rejection is often the case for those who make contributions which challenge the accepted dogma.  In Everett's case, he did not live to see his work vindicated as more and more practicing physicists accept the many worlds view, owing to the non-collapsing wave function in Hilbert space.


                  “There are three stages of scientific discovery: first people deny it is true; then they deny it is important; finally they credit the wrong person.”  ― Alexander von Humboldt

                    • Re: Is a collapse of wave function real?
                      Mitsuru Yamada

                      Yes, it is.

                      Dogma in science is a bad thing.

                      "Scientific explanation is never complete, for it produces only an approximate working model of nature as we understand it at a particular time and within the social framework of that time.  Science is badly misrepresented when it is portrayed as giving final and dogmatic truths."  - Quotation from some book.

                        • Re: Is a collapse of wave function real?
                          Mitsuru Yamada

                          Dear all,

                          I am now reading a John Gribbin's book titled "Schroedinger's Kittens (Back Bay Books)."  On pages 133-135, there is a paragraph that introduces us a report on an experiment conducted by a team of researchers at the US National Institute of Standard and Technology in Boulder Colorado.  According to the book, the team prepared about a thousand ions of beryllium ions and trapped and confined them in a small region of space by applying an appropriate electric field.  And they applied a radiation that changes the state of the beryllium ions from state "Level 1" to higher state "Level 2."  This experiment may be said to be an operation of heating and boiling the thausand beryllium ions in a pot.  So that, this experiment is dubbed "quantum pot."


                          But the nub of the experiment is whether the boiling process is observed or not.  The quantum pot boils until about 256 millisecond, that is, all beryllium ions become excited to "Level 2", only if we do not peek the ions in the pot at all.


                          In order to peek the ions in the pot during "boiling" process, the team devised a way.  They illuminated the pot with regularly flickering laser pulse of special frequency.  If the ions are in the state "Level 1", then they will respond by stepping up quickly to another state "Level 3" and soon stepping down spontaneously to the original state "Level 1" with associated emission of specific photons.  By detecting these specific photons, the team could know whether the ions were in the state "Level 1" or not.


                          Thus the conbination of illumination of flickering laser pulse and the detection of the specific photon constitutes the "peeking" action, because if the specific photon is detected, then we will know that some of the ions were in the state "Level 1."


                          The orthodox quantum mechanical interpretation of "boiling" is this.  Due to being be heated by the radiation, the wave function of the ions will spread energitically, and in 256 millisecond they will be in "100% Level 2 state" wave function.  But if we peek in the pot so frequently, then the wave function will not have enough time to spread to reach the "Level 2"  energy.  That is each time the peeking action is done, the wave function collapses back again and again to the original cool state "Level 1."


                          In fact, the quantum pot could not "boil", when the flickering interval of the "peeking" laser was set to 4 milliseconds,says the book.  At present, it seems to me that the collapse of a wave function is real.  And the NIST team of your country seems to have realized the collapse of a wave function artificially.


                          How do you think, Sirs?


                          Thanks for rerading

                  • Re: Is a collapse of wave function real?
                    Steven Cooke

                    Dear Mitsuru,


                    VERY interesting discussion - takes me back to my Quantum Mechanical courses in school!  Your later post did describe one possible observation of the effect.  As primarily an industrial scientist I always need to keep in mind that mathematics is just the tool - and usually an approximation of 'reality'!  To that end, the 'correctness' of both the theory, and particularly the mathematics must ultimately be based on the ability to correctly model (predict) physical observations.  MAYBE the model isn't quite right, yet!


                    My own example of the interface between the Dirac delta function and reality came while studying fluid dynamics.  The short form of the development was recognizing that the 'sonic boom' transition to trans-sound speed in aircraft was due to reaching that point in the airflow calculations.  So, whether the function would 'predict' the effect, or whether anyone immediately tried to 'model' what happened when we first exceeded the speed of sound in air, we will always have an observed effect and a mathematical model.  The scientific endeavor is to get them to correlate with each other.


                    Best regards,

                    Steven Cooke

                    Process Systems Consulting

                      • Re: Is a collapse of wave function real?
                        Mitsuru Yamada

                        Dear Stevens,

                        Thanks for your participation in this blog.  Your voice gives us a fresh air because you are an expert in aerodynamics.  Now because of your statement, the focus of the discussion seems to have moved slightly from the topic of quantum mechanical wave collapse to the topic of what a scientific endeavor is.


                        In Gribbin's book, he says that there is no perfect theory.  Only every theory is correct in its own limit of effectiveness.  And on some pages he writes about physical "reality."   That we are actually still unaware what the true reality of an entity is, so we may be simply enclosing the reality of the entity in a box on which we label a some name like "quark."  And further he says all physical theories are fictions.


                        I myself need more time to understand what he means.  I need to read the book again and again.



                        Mitsuru Yamada

                        An amature physicist