Physicist Stephen Hawking was among a select band of extraordinary "agents of change" who received America's highest civilian honour.
President Barack Obama joked that he would not try to attempt to explain the British scientist's work as he bestowed the Presidential Medal of Freedom on him.
Mr Hawking joined recipients yesterday including tennis legend Billie Jean King, South African cleric and civil rights activist Archbishop Desmond Tutu, film star Sidney Poitier and former Irish president Mary Robinson at a ceremony in the White House.
Others being honoured included Senator Edward Kennedy, who has been battling brain cancer and was not present, former Supreme Court Justice Sandra Day O'Connor and Nobel Peace Prize laureate Muhammad Yunus, who pioneered "microloans" to provide credit to poor people who lack collateral.
Mr Obama, awarding his first presidential medals, also gave a posthumous award to gay rights activist and San Francisco, California, politician Harvey Milk, who was assassinated in 1978.
Reflecting on those receiving the honour, President Obama said: "In a moment when cynicism and doubt too often prevail, when our obligations to each other are too often forgotten and when the road ahead can seem too long or hard to tread, these extraordinary men and women, these agents of change remind us that excellence is not beyond our abilities, that hope lies around the corner and that justice can still be won in the forgotten corners of the world.
"They remind us that we each have it within our powers to fulfil dreams, to advance the dreams of others and remake the world for our children."
On the 67-year-old author of A Brief History of Time, the president said: "From his wheelchair, he has led us on a journey to the farthest and strangest reaches of the cosmos. In so doing, he has stirred our imagination and showed us the power of the human spirit."
The Medal of Freedom was established by President Harry Truman in 1945 to recognise civilians for their efforts during the Second World War. President John F Kennedy reinstated the medal in 1963 to honour distinguished service.Reuse content