Do the virtual particles exist?

     Virtual particle are indeed real. They have observable effect that physicists have devised ways of measuring it. Quantum theory predicts that every particle spends some time as a combination of other particle in all possible ways. Quantum Mechanics allows and indeed requires temporary violations of conservation of energy. So, one particle can become a pair of heavier "virtual" particle which quickly rejoin into original particle almost as if they had never existed.

While the virtual particle are briefly part of our world, they can interact with other, less exotic particles and researchers can study these interactions to test prediction about virtual particle. In a hydrogen atom, Photon (elementary particle of electromagnetic radiation) binds together a negatively charged electron and a positively charged proton. Every photon will spend some time as virtual electron plus its antiparticle, the virtual position as described above. The hydrogen atom can be in more than one state, in one of those states, the atom

interacts a little differently with the virtual electron and positron than when it is in another, so quantum theory predicts the two states properties ( which would otherwise be identical) to diverge slightly as a result of other interaction. That divergence was measured in 1947 by Willis Lamb, who later received noble prize in physics for this work.

Another phenomenon involves elementary particle known as quarks specifically the "top quark", the heaviest of its six verities. In the early 1990 the European laboratories CERN produced million of particles called”z-bosons" and measured value deviated. A little from the mass apparently predicted by the standard model of particle physics but the difference could be explain by the time the z-boson spent as a virtual top quark if such a quark had a certain mass. The man of the top quark directly measured a few years later at Fermi National Accelerator Laboratory agreed with that obtained from the CERN analysis, providing another dramatic confirmation of our understanding of virtual particle.

Dhurba Raj Paudel

Bio group

Bsc 2^nd year