Question: The father of scientist Walter Alvarez recived a Nobel Prize in Physics in what year?

Context paragraphs:
Walter Alvarez: Walter Alvarez (born October 3, 1940) is a professor in the Earth and Planetary Science department at the University of California, Berkeley.  He is most widely known for the theory that dinosaurs were killed by an asteroid impact, developed in collaboration with his father, Nobel Prize winning physicist Luis Alvarez.

Frank Asaro: Frank Asaro (born Francesco Asaro, July 31, 1927 – June 10, 2014) was an Emeritus Senior Scientist at the Lawrence Berkeley National Laboratory associated with the University of California at Berkeley.  He is best known as the chemist who discovered the iridium anomaly in the Cretaceous–Paleogene boundary layer that led the team of Luis Alvarez, Walter Alvarez, Frank Asaro, and Helen Michel to propose the Asteroid-Impact Theory, which postulates that an asteroid hit the Earth sixty-five million years ago and caused mass extinction during the age of the dinosaurs.

Nobel Prize in Physics: The Nobel Prize in Physics (Swedish: "Nobelpriset i fysik" ) is a yearly award given by the Royal Swedish Academy of Sciences for those who conferred the most outstanding contributions for mankind in the field of physics.  It is one of the five Nobel Prizes established by the will of Alfred Nobel in 1895 and awarded since 1901; the others being the Nobel Prize in Chemistry, Nobel Prize in Literature, Nobel Peace Prize, and Nobel Prize in Physiology or Medicine.

List of Nobel laureates in Physiology or Medicine: The Nobel Prize in Physiology or Medicine (Swedish: "Nobelpriset i fysiologi eller medicin" ) is awarded annually by the Swedish Karolinska Institute to scientists and doctors in the various fields of physiology or medicine.  It is one of the five Nobel Prizes established by the 1895 will of Alfred Nobel (who died in 1896), awarded for outstanding contributions in chemistry, physics, literature, peace, and physiology or medicine.  As dictated by Nobel's will, the award is administered by the Nobel Foundation and awarded by a committee that consists of five members and an executive secretary elected by the Karolinska Institute.  While commonly referred to as the Nobel Prize in Medicine, Nobel specifically stated that the prize be awarded for "physiology or medicine" in his will.  Because of this, the prize can be awarded in a broader range of fields.  The first Nobel Prize in Physiology or Medicine was awarded in 1901 to Emil Adolf von Behring, of Germany.  Each recipient receives a medal, a diploma and a monetary award that has varied throughout the years.  In 1901, von Behring received 150,782 SEK, which is equal to 7,731,004 SEK in December 2008.  In 2013, the prize was awarded to James E. Rothman, Randy W. Schekman and Thomas C. Südhof; they were recognised "after discovering how cells precisely transport material".  The award is presented in Stockholm at an annual ceremony on December 10, the anniversary of Nobel's death.

Luis Walter Alvarez: Luis Walter Alvarez (June 13, 1911 – September 1, 1988) was an American experimental physicist, inventor, and professor who was awarded the Nobel Prize in Physics in 1968.  The American Journal of Physics commented, "Luis Alvarez was one of the most brilliant and productive experimental physicists of the twentieth century."

Nobel Prize in Literature: Since 1901, the Nobel Prize in Literature (Swedish: "Nobelpriset i litteratur" ) has been awarded annually to an author from any country who has, in the words of the will of Alfred Nobel, produced "in the field of literature the most outstanding work in an ideal direction" (original Swedish: "den som inom litteraturen har producerat det mest framstående verket i en idealisk riktning").  Though individual works are sometimes cited as being particularly noteworthy, here "work" refers to an author's work as a whole.  The Swedish Academy decides who, if anyone, will receive the prize in any given year.  The academy announces the name of the chosen laureate in early October.  It is one of the five Nobel Prizes established by the will of Alfred Nobel in 1895; the others are the Nobel Prize in Chemistry, Nobel Prize in Physics, Nobel Peace Prize, and Nobel Prize in Physiology or Medicine.

ChronoZoom: ChronoZoom is a free open source project that visualizes time on the broadest possible scale from the Big Bang to the present day.  Conceived by Walter Alvarez and Roland Saekow and developed by the department of Earth and Planetary Science at the University of California, Berkeley in collaboration with Microsoft Research and Moscow State University, Alvarez unveiled the first ChronoZoom prototype at UC Berkeley's 2010 Faculty Research Lecture.  That demo is available to the public online, and a second version rewritten in HTML5 is now available and open source.  ChronoZoom was inspired by the study of Big History, and it approaches the documentation and visualization of time and history in the same way that Google Earth deals with geography.  ChronoZoom allows users to see the true scale of time over cosmic, geologic, biological and social periods.

3581 Alvarez: 3581 Alvarez (1985 HC) is a Mars-crossing asteroid discovered on April 23, 1985, by Shoemaker, C. and Shoemaker, E. at Palomar.  Based upon lightcurve data, it has a synodic rotation period of  hours with an amplitude variation of in magnitude.  With a diameter of ~14 km, it is one of the largest Mars-crossing asteroids.  However, due to the high inclination of its orbit, it never actually passes through the orbit of Mars since at perihelion it is well away from the plane of Mars' orbit.  The asteroid is named after planetary scientist Walter Alvarez and his Nobel-prize winning father, physicist Luis Alvarez.

T. Rex and the Crater of Doom: T. rex and the Crater of Doom is a nonfiction book by professor Walter Alvarez that was published by Princeton University Press in 1997.  The book discusses the research and evidence that led to the creation of the Alvarez hypothesis, which explains how an impact event was the main cause that led to the Cretaceous–Paleogene extinction event.

Aage Bohr: Aage Niels Bohr (] ; 19 June 1922 – 8 September 2009) was a Danish nuclear physicist who shared the Nobel Prize in Physics in 1975 with Ben Mottelson and James Rainwater "for the discovery of the connection between collective motion and particle motion in atomic nuclei and the development of the theory of the structure of the atomic nucleus based on this connection".  Starting from Rainwater's concept of an irregular-shaped liquid drop model of the nucleus, Bohr and Mottelson developed a detailed theory that was in close agreement with experiments.  Since his father, Niels Bohr, had won the prize in 1922, he and his father were one of the six pairs of fathers and sons who have both won the Nobel Prize and one of the four pairs who have both won the Nobel Prize in Physics.

Supporting paragraphs: 3581 Alvarez Luis Walter Alvarez
Answer: 1968