Environmentalist is often a term used to describe impassioned tree huggers but the word literally means someone who studies the environment so environmentalists can be scientists as well. An ecologist studies the environment and an environmentalist wants to save the environment.
NEIL DEGRASSE TYSON: Just in case our human bodies can't live forever, this computer scientist is trying to design virtual replicas, avatars, that will. JASON LEIGH: An avatar is an instance of yourself that's digital, that will never die. NEIL DEGRASSE TYSON: Jason knows he can't really make you live forever, but he can use computers to preserve your thoughts, memories and even the way you look, for eternity.
Originally Answered: How long can a person live without a heartbeat? The heartbeat is the sound the heart valves' closing makes as the heart contracts and pushes oxygenated blood out to the aorta to supply oxygen to the body and deoxygenated blood to the pulmonary artery into the lungs to pick up more oxygen. The brain can survive for 4 minutes without oxygen, then brain cells start dying. So if there is no heartbeat, the heart is not contracting, the blood is not circulating through the body, and there is no oxygen supply. Other tissues and organs can live longer without oxygen. For example an arm or leg can survive up to 6 hours. That is why if there is a deep cut or wound, a tourniquet can be applied to stop the flow of blood to a limb for several hours if needed.