claim: Physics is a fundamental scientific discipline.
evidence: Longitudinal waves are waves in which the displacement of the medium is in the same direction as , or the opposite direction to , the direction of propagation of the wave .. Mechanical longitudinal waves are also called compressional or compression waves , because they produce compression and rarefaction when traveling through a medium , and pressure waves , because they produce increases and decreases in pressure .. rarefaction. rarefaction. The other main type of wave is the transverse / transversal wave , in which the displacements of the medium are at right angles to the direction of propagation .. transverse / transversal wave. Transverse wave. Some transverse waves are mechanical , meaning that the wave needs a medium to travel through .. Transverse mechanical waves are also called `` shear waves '' .. By acronym , `` longitudinal waves '' and `` transverse waves '' were occasionally abbreviated by some authors as `` L-waves '' and `` T-waves '' respectively for their own convenience .. acronym. acronym. While these two acronyms have specific meanings in seismology -LRB- L-wave for Love wave or long wave -RRB- and electrocardiography -LRB- see T wave -RRB- , some authors chose to use `` l-waves '' -LRB- lowercase ` L' -RRB- and `` t-waves '' instead , although they are not commonly found in physics writings except for some popular science books .. seismology. seismology. Love wave. Love wave. electrocardiography. electrocardiography. T wave. T wave