Primary waves travel through Earthâs crust at an average speed. of about 5 kilometers per second (3 mi/s). Primary waves can travel. through solids, liquids, and gases. As they pass through a material, the. particles of the material are slightly pushed together and pulled apart.
Why This Occurs. Emotional detachment is usually an issue caused by severe, intense anxiety - most notably panic attacks, although any form of severe anxiety can cause emotional detachment. While it's not entirely clear what causes this detachment, it most likely is a coping mechanism for the brain.
1 If a headache follows the flashes, it is called a migraine headache.. If these flashes or lines of light occur without a headache, it is called an ophthalmic migraine, or a migraine without a headache.  Posterior vitreous detachment - Posterior vitreous detachment (PVD) is a common condition usually caused by aging. The vitreous, which lies against the retina, is the jelly-like substance that fills the center of the eye. Made mostly of water, the vitreous fluid gives the eye its shape. As we get older, the composition of the vitreous changes, and becomes less firm. This change sometimes causes the vitreous to pull on the retina. If the force of the pulling becomes strong enough, the vitreous may actually separate from the retina. When this occurs, we see flashes of light or stars. Most of the time a PVD is annoying but harmless. However, about 5% of the time, a PVD can cause a retinal tear or detachment.