Problem: Extract the answer to the question from the following context. Question: Blackbody photons make it impossible to achieve what? Context: In quantum mechanics and quantum field theory, the vacuum is defined as the state (that is, the solution to the equations of the theory) with the lowest possible energy (the ground state of the Hilbert space). In quantum electrodynamics this vacuum is referred to as 'QED vacuum' to distinguish it from the vacuum of quantum chromodynamics, denoted as QCD vacuum. QED vacuum is a state with no matter particles (hence the name), and also no photons. As described above, this state is impossible to achieve experimentally. (Even if every matter particle could somehow be removed from a volume, it would be impossible to eliminate all the blackbody photons.) Nonetheless, it provides a good model for realizable vacuum, and agrees with a number of experimental observations as described next.

A: QED vacuum

Problem: Extract the answer to the question from the following context. Question: what type of machine is mentioned first? Context: Examples of energy transformation include generating electric energy from heat energy via a steam turbine, or lifting an object against gravity using electrical energy driving a crane motor. Lifting against gravity performs mechanical work on the object and stores gravitational potential energy in the object. If the object falls to the ground, gravity does mechanical work on the object which transforms the potential energy in the gravitational field to the kinetic energy released as heat on impact with the ground. Our Sun transforms nuclear potential energy to other forms of energy; its total mass does not decrease due to that in itself (since it still contains the same total energy even if in different forms), but its mass does decrease when the energy escapes out to its surroundings, largely as radiant energy.

A: turbine

Problem: Extract the answer to the question from the following context. Question: What location sold less slaves in the 1600s, North Africa or the Nile river? Context: During the 16th and 17th centuries slave traders began to raid the region as part of the expansion of the Saharan and Nile River slave routes. Their captives were slaved and shipped to the Mediterranean coast, Europe, Arabia, the Western Hemisphere, or to the slave ports and factories along the West and North Africa or South the Ubanqui and Congo rivers. In the mid 19th century, the Bobangi people became major slave traders and sold their captives to the Americas using the Ubangi river to reach the coast. During the 18th century Bandia-Nzakara peoples established the Bangassou Kingdom along the Ubangi River.

A: North Africa

Problem: Extract the answer to the question from the following context. Question: What does the National HIstorical Publications and Records Commission do? Context: The National Historical Publications and Records Commission (NHPRC)the agency's grant-making armawards funds to state and local governments, public and private archives, colleges and universities, and other nonprofit organizations to preserve and publish historical records. Since 1964, the NHPRC has awarded some 4,500 grants.

A:
awards funds