Core–mantle boundary Core–mantle boundary The core–mantle boundary (CMB in the parlance of solid earth geophysicists) of the Earth lies between the planet's silicate mantle and its liquid iron-nickel outer core. This boundary is located at approximately 2891 km (1796 mi) depth beneath the Earth's surface. The boundary is observed via the discontinuity in seismic wave velocities at that depth due to the differences between the acoustic impedances of the solid mantle and the molten outer core. P-wave velocities are much slower in the outer core than in the deep mantle while S-waves do not exist at all in the liquid portion of
What the Bleep Do We Know!? "What the Bleep Do We Know!?" have described distinct assertions made in the film as pseudoscience. Lisa Randall refers to the film as "the bane of scientists". Amongst the assertions in the film that have been challenged are that water molecules can be influenced by thought (as popularized by Masaru Emoto), that meditation can reduce violent crime rates, and that quantum physics implies that "consciousness is the ground of all being." The film was also discussed in a letter published in "Physics Today" that challenges how physics is taught, saying teaching fails to "expose the mysteries physics has encountered [and]