If we wish to draw philosophical conclusions about our own existence, our significance, and the significance of the universe itself, our conclusions should be based on empirical knowledge. A truly open mind means forcing our imaginations to conform to the evidence of reality, and not vice versa, whether we like the implications.

— Lawrence M. Krauss

In 5 billion years, the expansion of the universe will have progressed to the point where all other galaxies will have receded beyond detection. Indeed, they will be receding faster than the speed of light, so detection will be impossible. Future civilizations will discover science and all its laws, and never know about other galaxies or the cosmic background radiation. They will inevitably come to the wrong conclusion about the universe...... We live in a special time, the only time, where we can observationally verify that we live in a special time.

— Lawrence M. Krauss

[I]n science we have to be particularly cautious about 'why' questions. When we ask, 'Why?' we usually mean 'How?' If we can answer the latter, that generally suffices for our purposes. For example, we might ask: 'Why is the Earth 93 million miles from the Sun?' but what we really probably mean is, 'How is the Earth 93 million miles from the Sun?' That is, we are interested in what physical processes led to the Earth ending up in its present position. 'Why' implicitly suggests purpose, and when we try to understand the solar system in scientific terms, we do not generally ascribe purpose to it.

— Lawrence M. Krauss

It never ceases to amaze me that every second of every day, more than 6,000 billion neutrinos coming from nuclear reactions inside the sun whiz through my body, almost all of which will travel right through the earth without interruption.

— Lawrence M. Krauss

It's hard to imagine a more extraordinary claim than that some hidden intelligence created a universe of more than a hundred billion galaxies, each containing more than a hundred billion stars, and then waited more than 13.7 billion years until a planet in a remote corner of a single galaxy evolved an atmosphere sufficiently oxygenated to support life, only to then reveal his existence to an assortment of violent tribal groups before disappearing again.

— Lawrence M. Krauss

I've told you two things : First, you're much more insignificant than you ever imagined and second, the future is miserable. But you should be happy, because we may live in a universe without purpose, but that means the purpose in our lives is the purpose we create. And we should consider ourselves fortunate to have evolved in this place in the middle of nowhere and evolved a consciousness so we can understand the universe from the earliest moments of the big bang to the far future. So instead of being depressed, you should enjoy your brief moment in the sun.

— Lawrence M. Krauss

Keeping religion immune from criticism is both unwarranted and dangerous.

— Lawrence M. Krauss

Metaphysical speculation is independent of the physical validity of the Big Bang itself and is irrelevant to our understanding of it.

— Lawrence M. Krauss

More often than you might think, teaching science is inseparable from teaching doubt.

— Lawrence M. Krauss

Neutrinos alone, among all the known particles, have ethereal properties that are striking and romantic enough both to have inspired a poem by John Updike and to have sent teams of scientists deep underground for 50 years to build huge science-fiction-like contraptions to unravel their mysteries.

— Lawrence M. Krauss