4185 Phystech, provisional designation 1975 ED, is a Florian or background asteroid from the inner regions of the asteroid belt, approximately 6 kilometers (4 miles) in diameter. It was discovered on 4 March 1975, by Soviet astronomer Tamara Smirnova at the Crimean Astrophysical Observatory in Nauchnij, on the Crimean peninsula.^[1] The presumed S-type asteroid has a rotation period of 4.67 hours. It is named in honor of the Moscow Institute of Physics and Technology ("PhysTech") on its 50th anniversary.^[1]

Phystech is a non-family asteroid of the main belt's background population when applying the hierarchical clustering method to its proper orbital elements.^[3][4] Based on osculating Keplerian orbital elements, the asteroid has also been classified as a member of the Flora family (402), a giant asteroid family and the largest family of stony asteroids in the main-belt.^[5]

It orbits the Sun in the inner asteroid belt at a distance of 2.0–2.4 AU once every 3 years and 4 months (1,206 days; semi-major axis of 2.22 AU). Its orbit has an eccentricity of 0.10 and an inclination of 2° with respect to the ecliptic.^[2] The body's observation arc begins with a precovery taken at Palomar Observatory in October 1953, more than 21 years prior to its official discovery observation at Nauchnij.^[1]

Phystech is an assumed stony S-type asteroid, based on its family classification.^[5]

This minor planet was named after the Moscow Institute of Physics and Technology (informally: "PhysTech"; Физтех) on the occasion of its 50th anniversary in 1996, based on a proposal by the Institute of Theoretical Astronomy (ITA) in Saint Petersburg, Russia.^[1] The official naming citation was published by the Minor Planet Center on 22 February 1997 (M.P.C. 29143).^[7]