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Portrait of Arthur Ashkin
Photo: Bengt Nyman from Vaxholm, Sweden, Arthur Ashkin EM1B5678 · CC BY 2.0 via Wikimedia Commons

Nobel Prize in Physics · 2018

Arthur Ashkin

He turned laser light into tweezers that can hold a living cell or a single molecule without touching it.

The Nobel citation: “for the optical tweezers and their application to biological systems”
Born
September 2, 1922, New York, NY, USA
Died
September 21, 2020, Rumson, NJ, USA
Shared with
Gérard Mourou, Donna Strickland
Affiliation at the time
Bell Laboratories, USA

Physics prize

2018

Shared with 2 other laureates.

Age that year

96years

Born in 1922.

Sources cited

17

Fact-checked September 24, 2026.

  • At 96, Ashkin was the oldest person ever awarded a Nobel Prize at the time of his 2018 win.
  • Bell Labs' own theory department turned down his first light-trapping paper in internal review in 1970. It went on to be cited more than 5,000 times.
  • He learned his light trap could hold living bacteria by accident: virus samples left open overnight filled up with bacteria, and the trap caught them.
  • His father left the Russian Empire stateless; an immigration agent shortened the family name from Ashkenazi to Ashkin.
  • He held 47 patents, and after retiring he kept experimenting in his basement, working on cheaper solar power.

The breakthrough

Optical tweezers: holding cells and molecules with a beam of light

Light carries momentum, so it gives a tiny push to whatever it hits. Sunlight's push is far too weak to feel. Ashkin realized that a laser, which packs light into a narrow, intense beam, could push hard enough to move very small objects. By his estimate, a one-watt laser pushes on a glass bead one micrometre wide with a force about a million times the bead's weight. He also noticed something surprising: a clear bead in a laser beam gets pulled toward the brightest part of the beam, because the bead bends the light passing through it. In 1970 he used two laser beams pointing at each other to trap beads. Next he levitated beads on a single upward beam. Then he found that one beam, focused hard through a strong microscope lens, could hold a bead still in all three directions. Think of a boat in a river: the current pushes it downstream, but a strong whirlpool can hold it in one spot. Here the forward push of the light is the current and the pull toward the bright focus is the whirlpool. He called this single-beam trap optical tweezers. In 1987 he used tweezers to hold viruses, then showed that infrared tweezers could hold living bacteria without harming them, letting scientists grab, move and measure the machinery of life.[2],[3],[4],[5]

“I have always been fascinated by the forces that light can exert on objects.”
Arthur Ashkin, From the written summary of his 2018 Nobel Lecture, which a Bell Labs colleague delivered for him in Stockholm.[5]

What it meant for humanity

Ashkin's tweezers gave biology a way to touch single molecules. Before them, scientists mostly studied molecules in huge crowds and saw only averages. With a bead held in a laser trap and attached to one protein or one strand of DNA, researchers could watch a single molecule work and measure the forces it made. Steven Block's lab used this to show that kinesin, a motor protein that hauls cargo inside cells, walks in steps of 8 nanometres. Later his lab watched a single RNA polymerase, the enzyme that reads genes, move along DNA one base pair at a time, a step of 3.4 angstroms. Other groups used tweezers to learn how bacteria spin their tails and how forces act on DNA. The Nobel committee describes laser tweezers as standard equipment in many laboratories, and several companies now sell them. Ashkin's light-force work also reached atoms. With colleagues at Bell Labs, including future laureate Steven Chu, he took part in the first "optical molasses", which chilled a cloud of atoms with laser light, and the first optical trapping of atoms, work that fed the field of ultracold atoms. The benefits so far are mainly knowledge: a deeper understanding of how the molecules in our cells move, copy genes and fold. Newer holographic versions can run thousands of traps at once, for example to sort healthy blood cells from infected ones, which the Nobel committee says could help research on malaria.

  • Optical tweezers showed that the motor protein kinesin moves along the cell's internal skeleton in discrete steps of 8 nanometres (Block lab, 1993).[4],[5]
  • Dual optical traps revealed a single RNA polymerase enzyme stepping along DNA one base pair (3.4 angstroms) at a time, the highest-resolution measurement made directly on a single enzyme up to then (2005).[5]
  • In 1987 Ashkin showed that infrared laser tweezers could hold living bacteria, which kept reproducing inside the trap, opening the method to living cells.[3],[4],[6]
  • Ashkin was the first to observe optical gradient forces on atoms and took part in the first optical molasses and first optical trapping of atoms at Bell Labs.[6],[7],[8]
  • The Nobel committee describes laser tweezers as standard equipment in many biology laboratories, and several companies now sell them.[4],[5]

Impact in numbers

Ashkin's impact is mostly on knowledge. Optical tweezers let biologists grab, move and weigh the forces of single cells, organelles and molecules, which turned the mechanics of life into something that could be measured directly. That work showed how motor proteins walk, how enzymes read DNA, and how molecules fold. His studies of light forces on atoms also fed the growth of ultracold-atom physics. We record no quantified claims. Tweezers are a research instrument, and we found no approved therapy, crop or product whose value traces mainly to them, so any count of lives or people helped would be invented. Commercial market estimates for 2024 disagree by a factor of three and mix in magnetic tweezers, so they are too weak to support an economic total. No harms are documented.

Fundamental scienceHealthTechnology

No number is given here on purpose. Some contributions cannot be counted honestly, and we would rather describe them than invent a figure.

The double edge

We found no documented harms from optical tweezers, which are used mainly as a laboratory research tool. The one lasting controversy is about credit. Ashkin's biography on the Nobel Prize website, written at the time of his award, says it is generally recognized that he should have shared the 1997 physics prize for laser cooling and trapping of atoms, because his optical traps were used in the prize-winning experiments. The 1997 committee did not include him. In his Nobel lecture he wrote that he produced his 2006 book on optical trapping partly to answer researchers who claimed that magneto-optical traps mattered much more than optical tweezers.

  • Minor

    Dispute over credit for trapping atoms with light

    Ashkin's biography on the Nobel Prize website, written at the time of his 2018 award, states that he is generally recognized as deserving a share of the 1997 physics prize, which went to Steven Chu, Claude Cohen-Tannoudji and William Phillips for cooling and trapping atoms with laser light. His Nobel lecture says he wrote a 2006 book on optical trapping partly to rebut claims that magneto-optical traps were more important than optical tweezers.[2],[5],[17]

Against the odds

Ashkin's own path in America was comparatively open, but his family's story began under Tsarist rule. In the Russian Empire most Jews were confined to the Pale of Settlement, faced limits on where they could live, study and work, and lived through waves of pogroms in 1881 to 1884 and 1903 to 1906 that drove a steady stream of Jewish emigration to America. Ashkin's father, Isadore, was raised in an orphanage. When the passport meant to carry him out of Russia never arrived, he was left stateless, paid his savings for passage on a sealed train to Holland, and crossed to New York in steerage. Ashkin grew up in Brooklyn during the Great Depression and went to public schools. Elite colleges had their own barriers: Columbia, where he enrolled, had cut its share of Jewish students from about 40 percent to 22 percent in the early 1920s, and many private colleges restricted Jewish admissions by 1930. We found no record that Ashkin was personally turned away. War interrupted his studies, and his early Bell Labs career was rocky: he was nearly fired after a year, and the lab's theorists tried to block his first light-trapping paper.

  • —

    Other

    His father, an orphan in the Russian Empire, lent his passport to an older brother fleeing army service. When it was never mailed back he was left stateless, and paid his savings for a sealed train to Holland and steerage passage to New York.[2]

  • —

    Discrimination

    Jews in the Russian Empire were largely confined to the Pale of Settlement, restricted in education and work, and hit by waves of pogroms in 1881-1884 and 1903-1906 that pushed many to emigrate.[15],[16]

  • —

    Quota

    Columbia, where Ashkin enrolled in 1940, had cut Jewish enrollment from about 40 to 22 percent in the early 1920s, and many private colleges restricted Jewish admissions by 1930. We found no evidence that he was personally held back.[2],[14]

  • 1942

    War

    World War II interrupted his Columbia studies. He was drafted and spent the war as a technician building magnetrons for radar at Columbia's Radiation Laboratory.[2],[5],[9]

  • 1970

    Other

    Bell Labs' theory department judged his first optical-trapping paper to contain nothing new; his boss overruled them, and the paper was accepted at once.[2]

Jewish background

Both parents JewishCulturally Jewish

Ashkin was born in Brooklyn to Jewish immigrants from Eastern Europe. His father, Isadore, grew up in an orphanage in the Russian Empire (sources link the family to Kiev and Odessa). His mother, Anna Fishman, arrived in America at age two from Galicia, a region now split between Poland and Ukraine. The family name was Ashkenazi until an immigration agent shortened it. Ashkin and his wife, Aline, were longtime members of Congregation B'nai Israel in Rumson, New Jersey, whose rabbi was among the first to congratulate him on the Nobel. We found no statement from Ashkin himself about religious belief or practice.[2],[6],[7],[8],[11],[12]

Key dates

  1. September 2, 1922

    Born in Brooklyn, New York, the second son of Jewish immigrants Isadore and Anna Ashkin.[1],[2],[7]

  2. 1940

    Enrolls at Columbia College to study physics.[2]

  3. 1942

    Drafted into the Army in World War II; builds high-power magnetrons for radar at Columbia's Radiation Laboratory until 1945.[5],[8],[9]

  4. 1947

    Earns his bachelor's degree in physics from Columbia.[7],[10]

  5. 1952

    Completes a PhD in nuclear physics at Cornell and joins Bell Labs in New Jersey.[5],[6],[7]

  6. 1954

    Marries Aline, a Cornell chemistry student he met on the shore of Lake Cayuga.[2]

  7. 1970

    Publishes the first paper on trapping small particles with laser light, using two opposing beams.[2],[5]

  8. 1971

    Levitates small glass spheres on a single upward laser beam.[2],[6]

  9. 1986

    Publishes the single-beam optical trap, soon called optical tweezers. The same year he, Steven Chu, John Bjorkholm and colleagues at Bell Labs trap atoms with light.[2],[6],[7]

  10. 1987

    Uses optical tweezers to trap viruses and, with infrared light, living bacteria without harming them.[3],[4],[6]

  11. 1992

    Retires from Bell Labs after 40 years and builds a basement laboratory, where he later works on solar energy.[6],[9],[12],[13]

  12. 2004

    Receives the Harvey Prize from the Technion in Israel.[4],[6],[8]

  13. 2013

    Inducted into the U.S. National Inventors Hall of Fame; over his career he held 47 patents.[6],[8],[9],[10]

  14. October 2, 2018

    Awarded half of the Nobel Prize in Physics at age 96 for optical tweezers and their use in biology.[1],[3],[12]

  15. September 21, 2020

    Dies at home in Rumson, New Jersey, aged 98.[1],[7]

Sources

  1. 1.Arthur Ashkin - Facts · NobelPrize.org (Nobel Prize Outreach)
  2. 2.Arthur Ashkin - Biographical · NobelPrize.org (from Les Prix Nobel 2018), 2018
  3. 3.The Nobel Prize in Physics 2018 - Press release · The Royal Swedish Academy of Sciences / NobelPrize.org, 2018
  4. 4.The Nobel Prize in Physics 2018 - Popular information: Tools made of light · The Royal Swedish Academy of Sciences / NobelPrize.org, 2018
  5. 5.Optical Tweezers and their Application to Biological Systems (Nobel Lecture, delivered by René-Jean Essiambre) · NobelPrize.org (Nobel Foundation), 2018
  6. 6.Arthur Ashkin: Father of the optical tweezers (R.-J. Essiambre) · Proceedings of the National Academy of Sciences, vol. 118, no. 7, 2021
  7. 7.Arthur Ashkin (obituary by Kishan Dholakia and Halina Rubinsztein-Dunlop) · Physics Today (AIP), 2020
  8. 8.Arthur Ashkin (obituary) · Optica (formerly The Optical Society), 2020
  9. 9.Nobel-winning physicist Arthur Ashkin, Ph.D. '52, dies at 98 · Cornell Chronicle, 2020
  10. 10.Optical tweezer pioneer Arthur Ashkin dies aged 98 · Physics World (IOP Publishing), 2020
  11. 11.Rumson's Arthur Ashkin is oldest person to win Nobel · New Jersey Jewish News, 2018
  12. 12.Jewish researcher Arthur Ashkin, 96, shares Nobel Prize in Physics · Jewish Telegraphic Agency, 2018
  13. 13.96-year-old Jewish Nobel Prize winner says he's driven by science not accolades · The Times of Israel (with AP), 2018
  14. 14.How Jewish Quotas Began (Stephen Steinberg) · Commentary, 1971
  15. 15.Pale of Settlement (Encyclopaedia Judaica, Yehuda Slutsky) · Encyclopedia.com
  16. 16.Pogroms · United States Holocaust Memorial Museum, Holocaust Encyclopedia
  17. 17.The Nobel Prize in Physics 1997 - Summary · NobelPrize.org (Nobel Prize Outreach)

Fact-checked on September 24, 2026 by a separate AI fact-checking pass that re-opened the sources, with 8 corrections made. How we check

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