“The air around you is filled with floating atoms, sliding down the Earth's spacetime curve. Atoms first assembled in the cores of long-dead stars. Atoms within you, everywhere, disintegrating in radioactive decays. Beneath your feet, the floor - whose electrons refuse to let yours pass, thus making you able to stand and walk and run. Earth, your planet, a lump of matter made out of the three quantum fields known to mankind, held together by gravity, the so-called fourth force (even though it isn't a force), floating within and through spacetime.” MatterEarthForceStarsAirMankindAtomsGravityDeadDecayQuantumWalkRunPlanetElectronsStandDisintegrationAtomFloorSpacetimeRadioactiveAssembledRadioactive DecayCoresQuantum Fields Book:The Universe in Your Hand: A Journey Through Space, Time, and Beyond Source: The Universe in Your Hand: A Journey Through Space, Time, and Beyond
“Even today, more than eighty years after Oort's bold guess, we still don't have a clue what this dark matter is made of. We know it exists. We know where it is. We have maps of its presence within and around galaxies throughout the universe. We even have stringent constraints on what it is not, but we have no clue what it is. And yes, its presence is overwhelming: for every one kilogram of ordinary matter made out of neutrons and protons and electrons, there are five kilograms of dark matter, made out of who-knows-what.” MatterUniverseMapsOverwhelmingClueGalaxyPresenceKnowConstraintsWhatElectronsExistDark MatterGalaxiesMapWhereNeutronsGuessExistsProtonsOort Book:The Universe in Your Hand: A Journey Through Space, Time, and Beyond Source: The Universe in Your Hand: A Journey Through Space, Time, and Beyond