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108-403: AMMs have diversified rapidly over the past few decades and their design principles, properties, and characterization methods have been outlined better. A major starting point for the design of AMMs is to exploit the existing modes of motion in molecules, such as rotation about single bonds or cis-trans isomerization . Different AMMs are produced by introducing various functionalities, such as

216-424: A "bum". The young Feynman was heavily influenced by his father, who encouraged him to ask questions to challenge orthodox thinking, and who was always ready to teach Feynman something new. From his mother, he gained the sense of humor that he had throughout his life. As a child, he had a talent for engineering, maintained an experimental laboratory in his home, and delighted in repairing radios. This radio repairing

324-408: A "molecular machine" as a class of molecules typically described as an assembly of a discrete number of molecular components intended to produce mechanical movements in response to specific stimuli. The expression is often more generally applied to molecules that simply mimic functions that occur at the macroscopic level. A few prime requirements for a molecule to be considered a "molecular machine" are:

432-418: A "molecular shuttle" by Sir Fraser Stoddart . Building upon the assembly of mechanically linked molecules such as catenanes and rotaxanes as developed by Jean-Pierre Sauvage in the early 1980s, this shuttle features a rotaxane with a ring that can move across an "axle" between two ends or possible binding sites ( hydroquinone units). This design realized the well-defined motion of a molecular unit across

540-472: A bunch of professional soldiers," Wilson later recalled, "we signed up, en masse, to go to Los Alamos." Like many other young physicists, Feynman soon fell under the spell of the charismatic Oppenheimer, who telephoned Feynman long distance from Chicago to inform him that he had found a Presbyterian sanatorium in Albuquerque, New Mexico for Arline. They were among the first to depart for New Mexico, leaving on

648-586: A car from his friend Klaus Fuchs to drive to Albuquerque to see Arline. Asked who at Los Alamos was most likely to be a spy, Fuchs mentioned Feynman's safe-cracking and frequent trips to Albuquerque; Fuchs himself later confessed to spying for the Soviet Union . The FBI would compile a bulky file on Feynman, particularly in view of Feynman's Q clearance . Informed that Arline was dying, Feynman drove to Albuquerque and sat with her for hours until she died on June 16, 1945. He then immersed himself in work on

756-492: A diverse variety of AMMs are known today, experimental studies of these molecules are inhibited by the lack of methods to construct these molecules. In this context, theoretical modeling has emerged as a pivotal tool to understand the self-assembly or -disassembly processes in these systems. A wide range of applications have been demonstrated for AMMs, including those integrated into polymeric , liquid crystal , and crystalline systems for varied functions. Homogenous catalysis

864-556: A father of the Xbox , bought the van. Qantum was the license plate ID. At Caltech, Feynman investigated the physics of the superfluidity of supercooled liquid helium , where helium seems to display a complete lack of viscosity when flowing. Feynman provided a quantum-mechanical explanation for the Soviet physicist Lev Landau 's theory of superfluidity. Applying the Schrödinger equation to

972-488: A junior physicist, he was not central to the project. He administered the computation group of human computers in the theoretical division. With Stanley Frankel and Nicholas Metropolis , he assisted in establishing a system for using IBM punched cards for computation. He invented a new method of computing logarithms that he later used on the Connection Machine . An avid drummer, Feynman figured out how to get

1080-399: A living system that convert various forms of energy to mechanical work in order to drive crucial biological processes such as intracellular transport , muscle contractions , ATP generation and cell division . What would be the utility of such machines? Who knows? I cannot see exactly what would happen, but I can hardly doubt that when we have some control of the arrangement of things on

1188-400: A molecular scale we will get an enormously greater range of possible properties that substances can have, and of the different things we can do. Biological molecular machines have been known and studied for years given their vital role in sustaining life, and have served as inspiration for synthetically designed systems with similar useful functionality. The advent of conformational analysis, or

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1296-482: A movement due to external stimuli on a macro-scale are generally not included, since despite the molecular origin of the motion the effects are not useable on the molecular scale. This definition generally applies to synthetic molecular machines, which have historically gained inspiration from the naturally occurring biological molecular machines (also referred to as "nanomachines"). Biological machines are considered to be nanoscale devices (such as molecular proteins ) in

1404-662: A point of dating other men, but Feynman proposed in early 1960. They were married on September 24, 1960, at the Huntington Hotel in Pasadena . They had a son, Carl, in 1962, and adopted a daughter, Michelle, in 1968. Besides their home in Altadena, they had a beach house in Baja California , purchased with the money from Feynman's Nobel Prize. Feynman tried marijuana and ketamine at John Lilly 's sensory deprivation tanks , as

1512-414: A relativistic version. Feynman thought that he could do this, but when he went back to Bethe with his solution, it did not converge. Feynman carefully worked through the problem again, applying the path integral formulation that he had used in his thesis. Like Bethe, he made the integral finite by applying a cut-off term. The result corresponded to Bethe's version. Feynman presented his work to his peers at

1620-526: A study could capture the rotary motion of a decacyclene molecule on a copper-base metallic surface using a scanning tunneling microscope . Over the following decade, a broad variety of AMMs responding to various stimuli were invented for different applications. In 2016, the Nobel Prize in Chemistry was awarded to Sauvage, Stoddart, and Bernard L. Feringa for the design and synthesis of molecular machines. Over

1728-451: A suitable wavelength ), as seen in numerous designs consisting of stilbene and azobenzene units. Similarly, ring-opening and -closing reactions such as those seen for spiropyran and diarylethene can also produce curved shapes. Another common mode of movement is the circumrotation of rings relative to one another as observed in mechanically interlocked molecules (primarily catenanes). While this type of rotation can not be accessed beyond

1836-514: A train on March 28, 1943. The railroad supplied Arline with a wheelchair, and Feynman paid extra for a private room for her. There they spent their wedding anniversary. At Los Alamos, Feynman was assigned to Hans Bethe's Theoretical (T) Division, and impressed Bethe enough to be made a group leader. He and Bethe developed the Bethe–Feynman formula for calculating the yield of a fission bomb , which built upon previous work by Robert Serber . As

1944-491: A typical switch returns to its original state. Inspired by the use of kinetic control to produce work in natural processes, molecular motors are designed to have a continuous energy influx to keep them away from equilibrium to deliver work. Various energy sources are employed to drive molecular machines today, but this was not the case during the early years of AMM development. Though the movements in AMMs were regulated relative to

2052-657: A way of studying consciousness . He gave up alcohol when he began to show vague, early signs of alcoholism , as he did not want to consume anything that could damage his brain. Despite his curiosity about hallucinations , he was reluctant to experiment with LSD . Feynman had synesthesia , and said that mathematical symbols had different colors for him: "When I see equations, I see the letters in colors. I don't know why. I see vague pictures of Bessel functions with light-tan j's, slightly violet-bluish n's, and dark brown x's flying around." There had been protests over his alleged sexism in 1968, and again in 1972. Although there

2160-478: A widely used pictorial representation scheme for the mathematical expressions describing the behavior of subatomic particles , which later became known as Feynman diagrams . During his lifetime, Feynman became one of the best-known scientists in the world. In a 1999 poll of 130 leading physicists worldwide by the British journal Physics World , he was ranked the seventh-greatest physicist of all time. He assisted in

2268-487: Is a category of characterization techniques which use a range of principles to reveal the chemical composition, composition variation, crystal structure and photoelectric properties of materials. Some common examples of spectroscopy techniques include: A huge range of techniques are used to characterize various macroscopic properties of materials, including: Richard Feynman Richard Phillips Feynman ( / ˈ f aɪ n m ə n / ; May 11, 1918 – February 15, 1988)

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2376-493: Is a fundamental process in the field of materials science, without which no scientific understanding of engineering materials could be ascertained. The scope of the term often differs; some definitions limit the term's use to techniques which study the microscopic structure and properties of materials, while others use the term to refer to any materials analysis process including macroscopic techniques such as mechanical testing, thermal analysis and density calculation. The scale of

2484-412: Is a prominent example, especially in areas like asymmetric synthesis , utilizing noncovalent interactions and biomimetic allosteric catalysis. AMMs have been pivotal in the design of several stimuli-responsive smart materials, such as 2D and 3D self-assembled materials and nanoparticle -based systems, for versatile applications ranging from 3D printing to drug delivery. AMMs are gradually moving from

2592-540: Is either a Communist or very strongly pro-Communist—and as such is a very definite security risk. This man is, in my opinion, an extremely complex and dangerous person, a very dangerous person to have in a position of public trust ... In matters of intrigue Richard Feynman is, I believe immensely clever—indeed a genius—and he is, I further believe, completely ruthless, unhampered by morals, ethics, or religion—and will stop at absolutely nothing to achieve his ends. The U.S. government nevertheless sent Feynman to Geneva for

2700-661: Is known as the Hellmann–Feynman theorem . In 1939, Feynman received a bachelor's degree and was named a Putnam Fellow . He attained a perfect score on the graduate school entrance exams to Princeton University in physics—an unprecedented feat—and an outstanding score in mathematics, but did poorly on the history and English portions. The head of the physics department there, Henry D. Smyth , had another concern, writing to Philip M. Morse to ask: "Is Feynman Jewish? We have no definite rule against Jews but have to keep their proportion in our department reasonably small because of

2808-621: Is no evidence he supported discrimination against women in science, protestors "objected to his use of sexist stories about 'lady drivers' and clueless women in his lectures." Feynman recalled protesters entering a hall and picketing a lecture he was about to make in San Francisco, calling him a "sexist pig". Seeing the protesters, as Feynman later recalled the incident, he addressed institutional sexism by saying that "women do indeed suffer prejudice and discrimination in physics, and your presence here today serves to remind us of these difficulties and

2916-487: Is not to be expected according to Vallarta and Feynman". When they next met, Feynman asked gleefully whether Vallarta had seen Heisenberg's book. Vallarta knew why Feynman was grinning. "Yes," he replied. "You're the last word in cosmic rays." The other was his senior thesis, on "Forces in Molecules", based on a topic assigned by John C. Slater , who was sufficiently impressed by the paper to have it published. Its main result

3024-467: Is responsible for muscle contraction, kinesin , which moves cargo inside cells away from the nucleus along microtubules , and dynein , which moves cargo inside cells towards the nucleus and produces the axonemal beating of motile cilia and flagella . "[I]n effect, the [motile cilium] is a nanomachine composed of perhaps over 600 proteins in molecular complexes, many of which also function independently as nanomachines ... Flexible linkers allow

3132-459: Is the design of a photoresponsive crown ether containing an azobenzene unit, which could switch between cis and trans isomers on exposure to light and hence tune the cation-binding properties of the ether. In his seminal 1959 lecture There's Plenty of Room at the Bottom , Richard Feynman alluded to the idea and applications of molecular devices designed artificially by manipulating matter at

3240-482: The frigideira , a metal percussion instrument based on a frying pan. He was an enthusiastic amateur player of bongo and conga drums and often played them in the pit orchestra in musicals. He spent time in Rio with his friend Bohm, but Bohm could not convince Feynman to investigate Bohm's ideas on physics. Feynman did not return to Cornell. Bacher, who had been instrumental in bringing Feynman to Cornell, had lured him to

3348-508: The Physical Review . One of these, which was co-written with Manuel Vallarta , was entitled "The Scattering of Cosmic Rays by the Stars of a Galaxy". Vallarta let his student in on a secret of mentor-protégé publishing: the senior scientist's name comes first. Feynman had his revenge a few years later, when Heisenberg concluded an entire book on cosmic rays with the phrase: "such an effect

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3456-567: The Arista Honor Society , in his last year in high school he won the New York University Math Championship. His habit of direct characterization sometimes rattled more conventional thinkers; for example, one of his questions, when learning feline anatomy , was "Do you have a map of the cat?" (referring to an anatomical chart). Feynman applied to Columbia University but was not accepted because of its quota for

3564-533: The Pocono Conference in 1948. It did not go well. Julian Schwinger gave a long presentation of his work in quantum electrodynamics, and Feynman then offered his version, entitled "Alternative Formulation of Quantum Electrodynamics". The unfamiliar Feynman diagrams , used for the first time, puzzled the audience. Feynman failed to get his point across, and Paul Dirac , Edward Teller and Niels Bohr all raised objections. To Freeman Dyson , one thing at least

3672-723: The Richard C. Tolman professorship in theoretical physics at the California Institute of Technology. Feynman was a keen popularizer of physics through both books and lectures, including a 1959 talk on top-down nanotechnology called There's Plenty of Room at the Bottom and the three-volume publication of his undergraduate lectures, The Feynman Lectures on Physics . Feynman also became known through his autobiographical books Surely You're Joking, Mr. Feynman! and What Do You Care What Other People Think? , and books written about him such as Tuva or Bust! by Ralph Leighton and

3780-637: The University of Wisconsin–Madison as an assistant professor of physics, but was on unpaid leave during his involvement in the Manhattan Project. In 1945, he received a letter from Dean Mark Ingraham of the College of Letters and Science requesting his return to the university to teach in the coming academic year. His appointment was not extended when he did not commit to returning. In a talk given there several years later, Feynman quipped, "It's great to be back at

3888-524: The development of the atomic bomb during World War II and became known to the wider public in the 1980s as a member of the Rogers Commission , the panel that investigated the Space Shuttle Challenger disaster . Along with his work in theoretical physics, Feynman has been credited with having pioneered the field of quantum computing and introducing the concept of nanotechnology . He held

3996-516: The ferry to Staten Island , where they were married in the city office. The ceremony was attended by neither family nor friends and was witnessed by a pair of strangers. Feynman could kiss Arline only on the cheek. After the ceremony he took her to Deborah Hospital , where he visited her on weekends. In 1941, with World War II occurring in Europe but the United States not yet at war, Feynman spent

4104-539: The mobile protein domains connected by them to recruit their binding partners and induce long-range allostery via protein domain dynamics ." Other biological machines are responsible for energy production, for example ATP synthase which harnesses energy from proton gradients across membranes to drive a turbine-like motion used to synthesise ATP , the energy currency of a cell. Still other machines are responsible for gene expression , including DNA polymerases for replicating DNA, RNA polymerases for producing mRNA ,

4212-579: The principle of stationary action to problems of quantum mechanics, inspired by a desire to quantize the Wheeler–Feynman absorber theory of electrodynamics, and laid the groundwork for the path integral formulation and Feynman diagrams. A key insight was that positrons behaved like electrons moving backwards in time. James Gleick wrote: This was Richard Feynman nearing the crest of his powers. At twenty-three ... there may now have been no physicist on earth who could match his exuberant command over

4320-451: The spliceosome for removing introns , and the ribosome for synthesising proteins . These machines and their nanoscale dynamics are far more complex than any molecular machines that have yet been artificially constructed. Biological machines have potential applications in nanomedicine . For example, they could be used to identify and destroy cancer cells. Molecular nanotechnology is a speculative subfield of nanotechnology regarding

4428-431: The synagogue every Friday. However, by his youth, Feynman described himself as an "avowed atheist ". Many years later, in a letter to Tina Levitan , declining a request for information for her book on Jewish Nobel Prize winners, he stated, "To select, for approbation the peculiar elements that come from some supposedly Jewish heredity is to open the door to all kinds of nonsense on racial theory", adding, "at thirteen I

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4536-574: The "Mathematical Formulation of the Quantum Theory of Electromagnetic Interaction" in 1950 and "An Operator Calculus Having Applications in Quantum Electrodynamics" in 1951, he developed the mathematical basis of his ideas, derived familiar formulae and advanced new ones. While papers by others initially cited Schwinger, papers citing Feynman and employing Feynman diagrams appeared in 1950, and soon became prevalent. Students learned and used

4644-400: The 1954 Oppenheimer security hearing ("Where there's smoke there's fire") offended him. They separated on May 20, 1956. An interlocutory decree of divorce was entered on June 19, 1956, on the grounds of "extreme cruelty". The divorce became final on May 5, 1958. He begins working calculus problems in his head as soon as he awakens. He did calculus while driving in his car, while sitting in

4752-507: The California Institute of Technology (Caltech). Part of the deal was that he could spend his first year on sabbatical in Brazil. He had become smitten by Mary Louise Bell from Neodesha, Kansas . They had met in a cafeteria in Cornell, where she had studied the history of Mexican art and textiles. She later followed him to Caltech, where he gave a lecture. While he was in Brazil, she taught classes on

4860-604: The September 1958 Atoms for Peace Conference. On the beach at Lake Geneva , he met Gweneth Howarth, who was from Ripponden , West Yorkshire, and working in Switzerland as an au pair . Feynman's love life had been turbulent since his divorce; his previous girlfriend had walked off with his Albert Einstein Award medal and, on the advice of an earlier girlfriend, had feigned pregnancy and extorted him into paying for an abortion, then used

4968-511: The Talmud had evolved, and everything that was discussed was carefully recorded. Despite being impressed, Feynman was disappointed with the lack of interest for nature and the outside world expressed by the rabbis, who cared about only those questions which arise from the Talmud. Feynman attended Far Rockaway High School , which was also attended by fellow Nobel laureates Burton Richter and Baruch Samuel Blumberg . Upon starting high school, Feynman

5076-630: The University of California, but the head of the physics department, Raymond T. Birge , was reluctant. He made Feynman an offer in May 1945, but Feynman turned it down. Cornell matched its salary offer of $ 3,900 (equivalent to $ 66,000 in 2023) per annum. Feynman became one of the first of the Los Alamos Laboratory's group leaders to depart, leaving for Ithaca, New York , in October 1945. Because Feynman

5184-437: The advent of the electron microscope and secondary ion mass spectrometry in the 20th century has revolutionized the field, allowing the imaging and analysis of structures and compositions on much smaller scales than was previously possible, leading to a huge increase in the level of understanding as to why different materials show different properties and behaviors. More recently, atomic force microscopy has further increased

5292-412: The atomic level. This was further substantiated by Eric Drexler during the 1970s, who developed ideas based on molecular nanotechnology such as nanoscale "assemblers", though their feasibility was disputed . Though these events served as inspiration for the field, the actual breakthrough in practical approaches to synthesize artificial molecular machines (AMMs) took place in 1991 with the invention of

5400-578: The base of natural logarithms , e = 2.71828 ...), and found that the three filing cabinets where a colleague kept research notes all had the same combination. He left notes in the cabinets as a prank, spooking his colleague, Frederic de Hoffmann , into thinking a spy had gained access to them. Feynman's $ 380 (equivalent to $ 7,000 in 2023) monthly salary was about half the amount needed for his modest living expenses and Arline's medical bills, and they were forced to dip into her $ 3,300 (equivalent to $ 58,000 in 2023) in savings. On weekends he borrowed

5508-529: The biography Genius: The Life and Science of Richard Feynman by James Gleick . Feynman was born on May 11, 1918, in New York City, to Lucille ( née  Phillips ; 1895–1981), a homemaker , and Melville Arthur Feynman (1890–1946), a sales manager. Feynman's father was born into a Jewish family in Minsk , Russian Empire , and immigrated with his parents to the United States at the age of five. Feynman's mother

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5616-635: The broad array of reversible chemical reactions (heavily based on acid-base chemistry ) to switch molecules between different states. However, this comes with the issue of practically regulating the delivery of the chemical fuel and the removal of waste generated to maintain the efficiency of the machine as in biological systems. Though some AMMs have found ways to circumvent this, more recently waste-free reactions such based on electron transfers or isomerization have gained attention (such as redox-responsive viologens ). Eventually, several different forms of energy (electric, magnetic, optical and so on) have become

5724-489: The cafeteria at Cornell when someone tossed a dinner plate in the air. He read the work of Sir William Rowan Hamilton on quaternions , and tried unsuccessfully to use them to formulate a relativistic theory of electrons. His work during this period, which used equations of rotation to express various spinning speeds, ultimately proved important to his Nobel Prize–winning work, yet because he felt burned out and had turned his attention to less immediately practical problems, he

5832-603: The calutron, but Feynman and Paul Olum struggled to determine whether it was practical. Ultimately, on Lawrence's recommendation, the isotron project was abandoned. At this juncture, in early 1943, Robert Oppenheimer was establishing the Los Alamos Laboratory , a secret laboratory on a mesa in New Mexico where atomic bombs would be designed and built. An offer was made to the Princeton team to be redeployed there. "Like

5940-426: The conditions of Feynman's scholarship to Princeton was that he could not be married; nevertheless, he continued to see his high school sweetheart, Arline Greenbaum, and was determined to marry her once he had been awarded his PhD despite the knowledge that she was seriously ill with tuberculosis . This was an incurable disease at the time, and she was not expected to live more than two years. On June 29, 1942, they took

6048-470: The conventional solution-phase chemistry to surfaces and interfaces. For instance, AMM-immobilized surfaces (AMMISs) are a novel class of functional materials consisting of AMMs attached to inorganic surfaces forming features like self-assembled monolayers; this gives rise to tunable properties such as fluorescence, aggregation and drug-release activity. Most of these applications remain at the proof-of-concept level, and need major modifications to be adapted to

6156-471: The difficulty of placing them." Morse conceded that Feynman was indeed Jewish, but reassured Smyth that Feynman's "physiognomy and manner, however, show no trace of this characteristic". Attendees at Feynman's first seminar, which was on the classical version of the Wheeler–Feynman absorber theory , included Albert Einstein , Wolfgang Pauli , and John von Neumann . Pauli made the prescient comment that

6264-414: The engineers there in devising safety procedures for material storage so that criticality accidents could be avoided, especially when enriched uranium came into contact with water, which acted as a neutron moderator . He insisted on giving the rank and file a lecture on nuclear physics so that they would realize the dangers. He explained that while any amount of unenriched uranium could be safely stored,

6372-401: The enriched uranium had to be carefully handled. He developed a series of safety recommendations for the various grades of enrichments. He was told that if the people at Oak Ridge gave him any difficulty with his proposals, he was to inform them that Los Alamos "could not be responsible for their safety otherwise". Returning to Los Alamos, Feynman was put in charge of the group responsible for

6480-754: The field. A major route is the introduction of bistability to produce molecular switches, featuring two distinct configurations for the molecule to convert between. This has been perceived as a step forward from the original molecular shuttle which consisted of two identical sites for the ring to move between without any preference, in a manner analogous to the ring flip in an unsubstituted cyclohexane . If these two sites are different from each other in terms of features like electron density , this can give rise to weak or strong recognition sites as in biological systems — such AMMs have found applications in catalysis and drug delivery . This switching behavior has been further optimized to acquire useful work that gets lost when

6588-408: The groundwork for the path integral formulation and Feynman diagrams. With Murray Gell-Mann , Feynman developed a model of weak decay , which showed that the current coupling in the process is a combination of vector and axial currents (an example of weak decay is the decay of a neutron into an electron, a proton, and an antineutrino ). Although E. C. George Sudarshan and Robert Marshak developed

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6696-469: The history of furniture and interiors at Michigan State University . He proposed to her by mail from Rio de Janeiro, and they married in Boise, Idaho , on June 28, 1952, shortly after he returned. They frequently quarreled and she was frightened by what she decided was "a violent temper". Their politics were different; although he registered and voted as a Republican , she was more conservative, and her opinion on

6804-653: The house's convenience and said that "it's there that I did the fundamental work" for which he won the Nobel Prize. Feynman spent several weeks in Rio de Janeiro in July 1949. That year, the Soviet Union detonated its first atomic bomb , generating concerns about espionage. Fuchs was arrested as a Soviet spy in 1950 and the FBI questioned Bethe about Feynman's loyalty. Physicist David Bohm

6912-423: The industrial scale. Challenges in streamlining macroscale applications include autonomous operation, the complexity of the machines, stability in the synthesis of the machines and the working conditions. Characterization (materials science) Characterization , when used in materials science , refers to the broad and general process by which a material's structure and properties are probed and measured. It

7020-499: The introduction of bistability to create switches. A broad range of AMMs has been designed, featuring different properties and applications; some of these include molecular motors , switches , and logic gates . A wide range of applications have been demonstrated for AMMs, including those integrated into polymeric , liquid crystal , and crystalline systems for varied functions (such as materials research, homogenous catalysis and surface chemistry ). Several definitions describe

7128-477: The length of the molecule for the first time. In 1994, an improved design allowed control over the motion of the ring by pH variation or electrochemical methods, making it the first example of an AMM. Here the two binding sites are a benzidine and a biphenol unit; the cationic ring typically prefers staying over the benzidine ring, but moves over to the biphenol group when the benzidine gets protonated at low pH or if it gets electrochemically oxidized . In 1998,

7236-519: The living room, and while lying in bed at night. In the wake of the 1957 Sputnik crisis , the U.S. government's interest in science rose for a time. Feynman was considered for a seat on the President's Science Advisory Committee , but was not appointed. At this time, the FBI interviewed a woman close to Feynman, possibly his ex-wife Bell, who sent a written statement to J. Edgar Hoover on August 8, 1958: I do not know—but I believe that Richard Feynman

7344-592: The machine to click in musical rhythms. Other work at Los Alamos included calculating neutron equations for the Los Alamos "Water Boiler", a small nuclear reactor , to measure how close an assembly of fissile material was to criticality. On completing this work, Feynman was sent to the Clinton Engineer Works in Oak Ridge, Tennessee , where the Manhattan Project had its uranium enrichment facilities. He aided

7452-447: The maximum possible resolution for analysis of certain samples in the last 30 years. Microscopy is a category of characterization techniques which probe and map the surface and sub-surface structure of a material. These techniques can use photons , electrons , ions or physical cantilever probes to gather data about a sample's structure on a range of length scales. Some common examples of microscopy techniques include: Spectroscopy

7560-408: The molecule itself (because the rings are confined within one another), rotaxanes can overcome this as the rings can undergo translational movements along a dumbbell-like axis. Another line of AMMs consists of biomolecules such as DNA and proteins as part of their design, making use of phenomena like protein folding and unfolding. AMM designs have diversified significantly since the early days of

7668-613: The money to buy furniture. When Feynman found that Howarth was being paid only $ 25 a month, he offered her $ 20 (equivalent to $ 202 in 2022) a week to be his live-in maid. Feynman knew that this sort of behavior was illegal under the Mann Act , so he had a friend, Matthew Sands , act as her sponsor. Howarth pointed out that she already had two boyfriends, but decided to take Feynman up on his offer, and arrived in Altadena, California , in June 1959. She made

7776-418: The native materials of theoretical science. It was not just a facility at mathematics (though it had become clear ... that the mathematical machinery emerging in the Wheeler–Feynman collaboration was beyond Wheeler's own ability). Feynman seemed to possess a frightening ease with the substance behind the equations, like Einstein at the same age, like the Soviet physicist Lev Landau —but few others. One of

7884-474: The need to remedy them". In 1975, in Long Beach, CA , Feynman bought a Dodge Tradesman Maxivan with a bronze-khaki exterior and yellow-green interior, with custom Feynman diagram exterior murals. After Feynman's death, Gweneth sold the van for $ 1 to one of Feynman's friends, film producer Ralph Leighton, who later put it into storage, where it began to rust. In 2012, video game designer Seamus Blackley ,

7992-566: The number of Jews admitted . Instead, he attended the Massachusetts Institute of Technology , where he joined the Pi Lambda Phi fraternity. Although he originally majored in mathematics, he later switched to electrical engineering, as he considered mathematics to be too abstract. Noticing that he "had gone too far", he then switched to physics, which he claimed was "somewhere in between". As an undergraduate, he published two papers in

8100-525: The only university that ever had the good sense to fire me." As early as October 30, 1943, Bethe had written to the chairman of the physics department of his university, Cornell , to recommend that Feynman be hired. On February 28, 1944, this was endorsed by Robert Bacher , also from Cornell, and one of the most senior scientists at Los Alamos. This led to an offer being made in August 1944, which Feynman accepted. Oppenheimer had also hoped to recruit Feynman to

8208-538: The past few decades, AMMs have diversified rapidly and their design principles, properties, and characterization methods have been outlined more clearly. A major starting point for the design of AMMs is to exploit the existing modes of motion in molecules. For instance, single bonds can be visualized as axes of rotation, as can be metallocene complexes. Bending or V-like shapes can be achieved by incorporating double bonds , that can undergo cis-trans isomerization in response to certain stimuli (typically irradiation with

8316-441: The possibility of engineering molecular assemblers , biological machines which could re-order matter at a molecular or atomic scale. Nanomedicine would make use of these nanorobots , introduced into the body, to repair or detect damages and infections, but these are considered to be far beyond current capabilities. The construction of more complex molecular machines is an active area of theoretical and experimental research. Though

8424-459: The powerful new tool that Feynman had created. Computer programs were later written to evaluate Feynman diagrams, enabling physicists to use quantum field theory to make high-precision predictions . Marc Kac adapted Feynman's technique of summing over possible histories of a particle to the study of parabolic partial differential equations , yielding what is now known as the Feynman–Kac formula ,

8532-494: The presence of moving parts, the ability to consume energy, and the ability to perform a task. Molecular machines differ from other stimuli-responsive compounds that can produce motion (such as cis - trans isomers ) in their relatively larger amplitude of movement (potentially due to chemical reactions ) and the presence of a clear external stimulus to regulate the movements (as compared to random thermal motion ). Piezoelectric , magnetostrictive , and other materials that produce

8640-472: The primary energy sources used to power AMMs, even producing autonomous systems such as light-driven motors. Various AMMs have been designed with a broad range of functions and applications, several of which have been tabulated below along with indicative images: The most complex macromolecular machines are found within cells, often in the form of multi-protein complexes . Important examples of biological machines include motor proteins such as myosin , which

8748-524: The project and was present at the Trinity nuclear test . Feynman claimed to be the only person to see the explosion without the very dark glasses or welder's lenses provided, reasoning that it was safe to look through a truck windshield, as it would screen out the harmful ultraviolet radiation. The immense brightness of the explosion made him duck to the truck's floor, where he saw a temporary "purple splotch" afterimage . Feynman nominally held an appointment at

8856-499: The question showed that the superfluid was displaying quantum mechanical behavior observable on a macroscopic scale. This helped with the problem of superconductivity , but the solution eluded Feynman. It was solved with the BCS theory of superconductivity, proposed by John Bardeen , Leon Neil Cooper , and John Robert Schrieffer in 1957. Feynman, inspired by a desire to quantize the Wheeler–Feynman absorber theory of electrodynamics, laid

8964-445: The random thermal motion generally seen in molecules, they could not be controlled or manipulated as desired. This led to the addition of stimuli-responsive moieties in AMM design, so that externally applied non-thermal sources of energy could drive molecular motion and hence allow control over the properties. Chemical energy (or "chemical fuels") was an attractive option at the beginning, given

9072-403: The structures observed in materials characterization ranges from angstroms , such as in the imaging of individual atoms and chemical bonds, up to centimeters, such as in the imaging of coarse grain structures in metals. While many characterization techniques have been practiced for centuries, such as basic optical microscopy, new techniques and methodologies are constantly emerging. In particular

9180-492: The study of conformers to analyze complex chemical structures, in the 1950s gave rise to the idea of understanding and controlling relative motion within molecular components for further applications. This led to the design of "proto-molecular machines" featuring conformational changes such as cog-wheeling of the aromatic rings in triptycenes . By 1980, scientists could achieve desired conformations using external stimuli and utilize this for different applications. A major example

9288-604: The summer working on ballistics problems at the Frankford Arsenal in Pennsylvania . After the attack on Pearl Harbor brought the United States into the war, Feynman was recruited by Robert R. Wilson , who was working on means to produce enriched uranium for use in an atomic bomb , as part of what would become the Manhattan Project . At the time, Feynman had not earned a graduate degree. Wilson's team at Princeton

9396-706: The theoretical work and calculations on the proposed uranium hydride bomb , which ultimately proved to be infeasible. He was sought out by physicist Niels Bohr for one-on-one discussions. He later discovered the reason: most of the other physicists were too much in awe of Bohr to argue with him. Feynman had no such inhibitions, vigorously pointing out anything he considered to be flawed in Bohr's thinking. He said he felt as much respect for Bohr as anyone else, but once anyone got him talking about physics, he would become so focused he forgot about social niceties. Perhaps because of this, Bohr never warmed to Feynman. At Los Alamos, which

9504-504: The theoreticians were completely overshadowed by the achievements of the experimentalists, who reported the discovery of the Lamb shift , the measurement of the magnetic moment of the electron, and Robert Marshak 's two-meson hypothesis. Bethe took the lead from the work of Hans Kramers , and derived a renormalized non-relativistic quantum equation for the Lamb shift. The next step was to create

9612-436: The theory nearly simultaneously, Feynman's collaboration with Gell-Mann was seen as seminal because the weak interaction was neatly described by the vector and axial currents. It thus combined the 1933 beta decay theory of Enrico Fermi with an explanation of parity violation . Feynman attempted an explanation, called the parton model , of the strong interactions governing nucleon scattering. The parton model emerged as

9720-568: The theory would be extremely difficult to quantize, and Einstein said that one might try to apply this method to gravity in general relativity , which Sir Fred Hoyle and Jayant Narlikar did much later as the Hoyle–Narlikar theory of gravity . Feynman received a PhD from Princeton in 1942; his thesis advisor was John Archibald Wheeler . In his doctoral thesis entitled "The Principle of Least Action in Quantum Mechanics", Feynman applied

9828-482: The theory, which Feynman and Wheeler had tried, unsuccessfully, to work around. "Theoreticians", noted Murray Gell-Mann , "were in disgrace". In June 1947, leading American physicists met at the Shelter Island Conference . For Feynman, it was his "first big conference with big men ... I had never gone to one like this one in peacetime." The problems plaguing quantum electrodynamics were discussed, but

9936-509: The use of which extends beyond physics to many applications of stochastic processes . To Schwinger, however, the Feynman diagram was "pedagogy, not physics". By 1949, Feynman was becoming restless at Cornell. He never settled into a particular house or apartment, living in guest houses or student residences, or with married friends "until these arrangements became sexually volatile". He liked to date undergraduates, hire prostitutes, and sleep with

10044-665: The wives of friends. He was not fond of Ithaca's cold winter weather, and pined for a warmer climate. Above all, he was always in the shadow of Hans Bethe at Cornell. Despite all of this, Feynman looked back favorably on the Telluride House , where he resided for a large period of his Cornell career. In an interview, he described the House as "a group of boys that have been specially selected because of their scholarship, because of their cleverness or whatever it is, to be given free board and lodging and so on, because of their brains". He enjoyed

10152-559: Was an American theoretical physicist . He is best known for his work in the path integral formulation of quantum mechanics , the theory of quantum electrodynamics , the physics of the superfluidity of supercooled liquid helium , and in particle physics , for which he proposed the parton model . For his contributions to the development of quantum electrodynamics, Feynman received the Nobel Prize in Physics in 1965 jointly with Julian Schwinger and Shin'ichirō Tomonaga . Feynman developed

10260-482: Was arrested on December 4, 1950 and emigrated to Brazil in October 1951. Because of the fears of a nuclear war, a girlfriend told Feynman that he should also consider moving to South America. He had a sabbatical coming for 1951–1952, and elected to spend it in Brazil, where he gave courses at the Centro Brasileiro de Pesquisas Físicas . In Brazil, Feynman was impressed with samba music, and learned to play

10368-422: Was born and the family moved to Far Rockaway, Queens . Though separated by nine years, Joan and Richard were close, and they both shared a curiosity about the world. Though their mother thought women lacked the capacity to understand such things, Richard encouraged Joan's interest in astronomy, and Joan eventually became an astrophysicist. Feynman's parents were both from Jewish families, and his family went to

10476-554: Was born in the United States into a Jewish family. Lucille's father had emigrated from Poland, and her mother also came from a family of Polish immigrants. She trained as a primary school teacher but married Melville in 1917, before taking up a profession. Feynman was a late talker and did not speak until after his third birthday. As an adult, he spoke with a New York accent strong enough to be perceived as an affectation or exaggeration, so much so that his friends Wolfgang Pauli and Hans Bethe once commented that Feynman spoke like

10584-416: Was clear: Shin'ichirō Tomonaga , Schwinger and Feynman understood what they were talking about even if no one else did, but had not published anything. He was convinced that Feynman's formulation was easier to understand, and ultimately managed to convince Oppenheimer that this was the case. Dyson published a paper in 1949, which added new rules to Feynman's that told how to implement renormalization. Feynman

10692-451: Was experimenting with mathematical topics such as the half-derivative using his own notation. He created special symbols for logarithm , sine , cosine and tangent functions so they did not look like three variables multiplied together, and for the derivative , to remove the temptation of canceling out the d {\displaystyle d} 's in d / d x {\displaystyle d/dx} . A member of

10800-404: Was isolated for security, Feynman amused himself by investigating the combination locks on the cabinets and desks of physicists. He often found that they left the lock combinations on the factory settings, wrote the combinations down, or used easily guessable combinations like dates. He found one cabinet's combination by trying numbers he thought a physicist might use (it proved to be 27–18–28 after

10908-486: Was no longer working at the Los Alamos Laboratory, he was no longer exempt from the draft . At his induction physical, Army psychiatrists diagnosed Feynman as suffering from a mental illness and the Army gave him a 4-F exemption on mental grounds. His father died suddenly on October 8, 1946, and Feynman suffered from depression. On October 17, 1946, he wrote a letter to Arline, expressing his deep love and heartbreak. The letter

11016-593: Was not only converted to other religious views, but I also stopped believing that the Jewish people are in any way 'the chosen people '". Later in life, during a visit to the Jewish Theological Seminary , Feynman encountered the Talmud for the first time. He saw that it contained the original text in a little square on each page, and surrounding it were commentaries written over time by different people. In this way

11124-499: Was probably the first job Feynman had, and during this time he showed early signs of an aptitude for his later career in theoretical physics, when he would analyze the issues theoretically and arrive at the solutions. When he was in grade school, he created a home burglar alarm system while his parents were out for the day running errands. When Richard was five, his mother gave birth to a younger brother, Henry Phillips, who died at age four weeks. Four years later, Richard's sister Joan

11232-589: Was prompted to publish his ideas in the Physical Review in a series of papers over three years. His 1948 papers on "A Relativistic Cut-Off for Classical Electrodynamics" attempted to explain what he had been unable to get across at Pocono. His 1949 paper on "The Theory of Positrons" addressed the Schrödinger equation and Dirac equation , and introduced what is now called the Feynman propagator . Finally, in papers on

11340-635: Was quickly promoted to a higher math class. An IQ test administered in high school estimated his IQ at 125—high but "merely respectable", according to biographer James Gleick . His sister Joan, who scored one point higher, later jokingly claimed to an interviewer that she was smarter. Years later he declined to join Mensa International , saying that his IQ was too low. When Feynman was 15, he taught himself trigonometry , advanced algebra , infinite series , analytic geometry , and both differential and integral calculus . Before entering college, he

11448-399: Was sealed and only opened after his death. "Please excuse my not mailing this," the letter concluded, "but I don't know your new address." Unable to focus on research problems, Feynman began tackling physics problems, not for utility, but for self-satisfaction. One of these involved analyzing the physics of a twirling, nutating disk as it is moving through the air, inspired by an incident in

11556-483: Was surprised by the offers of professorships from other renowned universities, including the Institute for Advanced Study , the University of California, Los Angeles , and the University of California, Berkeley . Feynman was not the only frustrated theoretical physicist in the early post-war years. Quantum electrodynamics suffered from infinite integrals in perturbation theory . These were clear mathematical flaws in

11664-465: Was working on a device called an isotron, intended to electromagnetically separate uranium-235 from uranium-238 . This was done in a quite different manner from that used by the calutron that was under development by a team under Wilson's former mentor, Ernest O. Lawrence , at the Radiation Laboratory of the University of California . On paper, the isotron was many times more efficient than

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