Life in the UniverseAnswer
Could a planet without a star support life?
A world with no sunrise could still have internal heat. The question is whether it can keep water liquid and supply usable energy.
SECTION
Life in the Universe.
How did life begin—and are we alone?
How life began on Earth, how evolution works, and whether anyone else is out there, with the evidence labelled at every step.
FROM THE QUESTION LIBRARY
Short answers, with sources.
Life in the UniverseAnswer
Could there be life elsewhere in our solar system?
Mars and icy moons offer different evidence about possible habitats.
Life in the UniverseAnswer
Does evolution have a goal or a direction?
Evolution has no built-in destination or ability to plan ahead. It can nevertheless show directional change. The distinction is between a pattern we observe and a future goal.…
Life in the UniverseAnswer
How can humans and chimpanzees share so much DNA and still be so different?
Humans and chimpanzees inherited much of their DNA from a shared ancestor. Similar DNA can produce different bodies when some protein instructions and patterns of gene activity differ.…
Life in the UniverseAnswer
How can identical twins with the same DNA turn out so different?
Identical twins develop from one fertilized egg and begin with almost the same DNA. Yet their conditions before birth, later environments and gene activity can differ. Shared DNA…
Life in the UniverseAnswer
How closely related are all humans?
Any two people share almost all of their DNA, so here is what that number means, where our shared family tree leads, and what race does and does not capture.
Life in the UniverseAnswer
How did life on Earth begin?
Life showed up early on a young Earth, and nature can make some of its raw parts, but the step from chemistry to the first living cell is still one of science’s big open questions.
Life in the UniverseAnswer
How do astronomers find planets around other stars?
Distant worlds can reveal themselves through changes in starlight and the motion of their stars.
Life in the UniverseAnswer
How do bacteria become resistant to antibiotics?
Bacteria can resist an antibiotic through changes in their DNA or by acquiring resistance genes from other bacteria. The bacteria become resistant; the person’s body does not. Antibiotics…
Life in the UniverseAnswer
If we could replay the history of life, would evolution turn out the same?
Evolution mixes chance with patterns that repeat, so here is what flasks of bacteria, eyes that evolved more than once, and a famous debate reveal about how predictable life really is.
Life in the UniverseAnswer
Is life likely to be rare or common in the universe?
Planets turn out to be everywhere, but we still know of only one living world, so here is what the numbers say, where the arguments split, and how to judge the next headline.
Life in the UniverseAnswer
What decides which genes win in evolution: fitness, luck or timing?
Fitness, luck and timing can all matter. Which matters most depends on the population, its surroundings and which competing variants are available. What does survival of the fittest…
All 14 answers in Life in the Universe
- Could a planet without a star support life?
- Could there be life elsewhere in our solar system?
- Does evolution have a goal or a direction?
- How can humans and chimpanzees share so much DNA and still be so different?
- How can identical twins with the same DNA turn out so different?
- How closely related are all humans?
- How did life on Earth begin?
- How do astronomers find planets around other stars?
- How do bacteria become resistant to antibiotics?
- If we could replay the history of life, would evolution turn out the same?
- Is life likely to be rare or common in the universe?
- What decides which genes win in evolution: fitness, luck or timing?
- What is the Fermi paradox: if aliens exist, where is everybody?
- What would happen if we really found alien life, and have we ever come close?
Life in the UniverseEssay · personal view
We Are Already an Advanced Civilization
We keep imagining advanced civilizations as someone else, somewhere else. From the eyes of our ancestors—or another species—the advanced civilization may already be us.
Life in the UniverseEssay · personal view
The Questions I Would Ask an Alien
If I ever met a visitor from another world, I would skip the small talk. I would ask what its civilization knows about beginnings—and how it knows.
Life in the UniverseExplainer
The Fermi Paradox: Where Is Everybody?
Planets are everywhere, yet the sky seems silent. Here is what that silence does and doesn't tell us, and how scientists are listening now.
Life in the UniverseExplainer
How Did Life on Earth Begin?
Life appeared early on a young Earth, but no lab has yet recreated the leap from chemistry to biology, and the question remains open.
Life in the UniverseExplainer
How Does Evolution Actually Work?
Small inherited differences, filtered over countless generations, add up to the variety of life. Here is how evolution works and how we know.
Life in the UniverseExplainer
Are We Alone in the Universe?
Planets are common. Evidence of life beyond Earth has yet to be confirmed.