The US has issued its highest travel advisory, Level 4: “Do Not Travel,” for more than two dozen countries, advising American citizens to steer clear of travel there due to serious extreme safety and ...

The US State Department has issued a Level 4 “Do Not Travel” advisory for 21 countries due to extreme safety and security risks. US issues Level 4 "Do Not Travel" warning for 21 countries due to ...

Physics is the search for and application of rules that can help us understand and predict the world around us. Central to physics are ideas such as energy, mass, particles and waves. Physics attempts ...

Quantum physics is the study of matter and energy at its most fundamental level. A central tenet of quantum physics is that energy comes in indivisible packets called quanta. Quanta behave very ...