What Is Consciousness?
The hard problem of consciousness (David Chalmers, 1995): why does physical processing in the brain give rise to subjective experience? We can explain the brain mechanisms of vision, but not why there is something it is like to see red. Every neuroscientific explanation leaves the phenomenal gap open. Integrated Information Theory, Global Workspace Theory, and panpsychism are all proposed solutions; none is accepted.
What Is Dark Matter?
Sobre 27% of the universe's mass-energy is dark matter — matter that interacts gravitationally but not electromagnetically (so it emits no light). We know it exists from galaxy rotation curves, gravitational lensing, and cosmic structure formation. We have not directly detected it. WIMPs, axions, and sterile neutrinos are candidates; decades of experiments have found nothing.
How Did Life Begin?
Abiogenesis — the origin of life from non-living chemistry — is one of science's deepest open questions. The RNA world hypothesis proposes that self-replicating RNA molecules preceded DNA and proteins. Hydrothermal vent environments provide chemical energy. But no complete pathway from chemistry to the first replicating cell has been demonstrated.
Is There a Theory of Everything?
General relativity describes gravity; quantum mechanics describes the other three forces. They are mathematically incompatible at the Planck scale (10⁻³⁵ meters). String theory and loop quantum gravity are leading candidates for unification, but neither has made testable predictions yet confirmed. Physicists have sought quantum gravity for 80 years without experimental guidance.
Perguntas Frequentes
What is the hard problem of consciousness?
The hard problem, named by philosopher David Chalmers, is explaining why physical processes in the brain give rise to subjective experience — why there is something it is like to be conscious. Explaining the neural mechanisms of perception (the 'easy' problems) doesn't explain why those mechanisms produce phenomenal experience.
What is dark matter?
Dark matter is a hypothetical form of matter that does not interact with light but has gravitational effects. It accounts for ~27% of the universe's mass-energy. Evidence comes from galaxy rotation curves (stars orbit too fast for visible matter to hold them), gravitational lensing, and the large-scale structure of the universe. Its composition remains unknown.
What is the theory of everything in physics?
A theory of everything (TOE) is a hypothetical unified framework reconciling general relativity (which describes gravity at large scales) with quantum mechanics (which describes the other forces at small scales). String theory and loop quantum gravity are leading candidates, but neither has produced confirmed experimental predictions.