In the physical sciences, a particle is a small localized object to which can be ascribed several physical properties such as volume or mass. The word is rather general in meaning, and is refined as needed by various scientific fields.

Whether objects can be considered particles depends on the scale of the context; if an object's own size is small or negligible, or if geometrical properties and structure are irrelevant, then it can be considered a particle. For example, grains of sand on a beach can be considered particles because the size of one grain of sand (~1 mm) is negligible compared to the beach, and the features of individual grains of sand are usually irrelevant to the problem at hand. However, grains of sand would not be considered particles if compared to buckyballs (~1 nm).

The concept of particles is particularly useful when modelling nature, as the full treatment of many phenomena is complex. It can be used to make simplifying assumptions concerning the processes involved. Francis Sears and Mark Zemansky, in University Physics, give the example of calculating the landing location and velocity of a baseball thrown in the air. They gradually strip the baseball of most of its properties, by first idealizing it as a rigid smooth sphere, then by neglecting rotation, buoyancy and friction, ultimately reducing the problem to the ballistics of a classical point particle.

Joseph "Joe" Satriani (born July 15, 1956) is an American instrumental rock guitarist of Italian origin, multi-instrumentalist and multiple Grammy Award nominee. Early in his career, Satriani worked as a guitar instructor, and some of his former students have achieved fame such as Steve Vai, Larry LaLonde, Rick Hunolt, Kirk Hammett, Andy Timmons, Charlie Hunter, Kevin Cadogan and Alex Skolnick. Satriani has been a driving force in music credited to other musicians throughout his career, as a founder of the G3 tour, as well as performing in various positions with other musicians.

In 1988, Satriani was recruited by Mick Jagger as lead guitarist for Jagger's first solo tour. In 1994, Satriani was the lead guitarist for Deep Purple. Satriani worked with a range of guitarists, including Steve Vai, John Petrucci, Eric Johnson, Larry LaLonde, Yngwie Malmsteen, Brian May, Patrick Rondat, Andy Timmons, Paul Gilbert, Adrian Legg, and Robert Fripp through the annual G3 Jam Concerts. He is currently the lead guitarist for the supergroup Chickenfoot. Since 1988, Satriani has been using his own signature guitar, the Ibanez JS Series, which is sold in music stores worldwide.

DJ Logic (born Jason Kibler) is an American turntablist active primarily in jazz and with jam bands.

Kibler was born and raised in The Bronx. An early interest in hip hop led to his using the turntables, practicing often. Kibler was also interested in funk and jazz music, and began collaborating with various musicians. His own recordings are perhaps best described as contemporary soul jazz with a strong hip hop feel.

Kibler tours often with his own group, Project Logic, and has recorded or performed with Vernon Reid, moe., John Mayer, Medeski Martin & Wood, Bob Belden, Jack Johnson, Chris Whitley, Uri Caine, Christian McBride and others. On April 6, 2006, Kibler sat in with Bob Weir's Ratdog, adding his style to the famous Grateful Dead song combo "China Cat Sunflower/I Know You Rider". He is a founding member of The John Popper Project. On August 15, 2009, Kibler sat in with O.A.R. at Madison Square Garden, adding his style to their latest single "This Town".

His mentor was Vernon Reid, and the twosome recorded and toured occasionally as the Yohimbe Brothers with various guests. Kibler has appeared on studio and live performances with Reid's solo projects, and Reid also did a guest solo on one track from Kibler's original band, Eye and I, which also featured D.K. Dyson and Melvin Gibbs, the latter of which has played on all of the DJ Logic solo releases as well.

Don Lincoln is an American particle physics researcher at Fermi National Accelerator Laboratory and adjunct Professor of Physics at the University of Notre Dame. He received a Ph.D. in experimental particle physics from Rice University in 1994. In 1995, he was a codiscoverer of the top quark. He has coauthored hundreds of research papers and, more recently, contributed to ruling out possible values of the Higgs boson's mass.

Lincoln is a public speaker and science writer and has contributed many science articles in magazines that include Analog Science Fiction and Fact in July 2009. He is also the author of books describing particle physics written for the public. They are "Understanding the Universe: From Quarks to the Cosmos" (2004), "Understanding the Universe: From Quarks to the Cosmos (Revised edition)" (2012) and "The Quantum Frontier: The Large Hadron Collider" (2009).

In recent years, he has been heavily involved in research using the DZero detector at the Fermilab Tevatron and also at the Compact Muon Solenoid (CMS) on the Large Hadron Collider at CERN. His popularizations also include columns that translate CMS (monthly) and DZero (biweekly) physics measurements for the public.

Colm Kelleher is a research scientist and author. He received his PhD in biochemistry at Trinity College, Dublin and has 21 years of experience in the field of cell and molecular biology. In addition he was an adminisrator for a Nevada aerospace company, Space Sciences Inc., and was also Deputy Administrator of the NIDS, where he led the investigation at Skinwalker Ranch. He currently works in the biotechnology sector.

He has published 38 peer-reviewed scientific papers (in molecular biology, immunology, biochemistry and virology) as well as a number of articles in magazines such as OMNI and two books: Brain Trust (2004) and, with George Knapp, Hunt for the Skinwalker (2005).