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The concept of ‘relativistic mass’ has been around almost as long as relativity has. But is it a reasonable way to make sense of things?
Memorial day is a time to remember veterans killed in the line of service. These spaceflight heroes deserve to be remembered, too.
It's been 100 years since we discovered that the Universe was expanding. But if it's expanding, then what is it expanding into?
If our Universe were born a little differently, there wouldn't have been any planets, stars, galaxies, or chemically interesting reactions.
Einstein's most famous equation is E = mc², which describes the rest mass energy inherent to particles. But motion matters for energy, too.
A surprising JWST discovery around Fomalhaut has a different, superior explanation: not a great dust cloud, but a mere background object.
Massive objects like black holes, stars, and rogue planets routinely pass near our Solar System. An ensuing comet storm could destroy us.
Yes, "the laws of physics break down" at singularities. But something really weird must have happened for black holes to not possess them.
A new, unexpected brightening, just 3 years after a massive dimming event, has astronomers watching Betelgeuse. Is a supernova imminent?
The odds are slim, but the consequences would be literally world-ending. There really is a chance of a black hole devouring the Earth.
The problem of the electroweak horizon haunts the standard model of cosmology and beckons us to ask how deep a rethink the model may need.
The standard model of cosmology has a big new problem: Some galaxies seem to be too old.
It's not about fairness. It's about using every possible advantage.
All forms of energy affect the expanding Universe. But if matter and radiation slow the expansion down, how does dark energy speed it up?
The best evidence for dark matter is astrophysical and indirect. Do new lensing observations point to ultra-light, wave-like dark matter?
From quarks and gluons to giant galaxy clusters, everything that exists in our Universe is determined by what is (and isn't) bound together.
What would become the Big Bang model started from a crucial idea: that the young Universe was denser and hotter.
The Universe is grand, awe-inspiring, and greater than we likely imagine. Even astrophysicists get anxious thinking about it, but we cope.
For many years, some cosmologists embraced the idea of an eternal, steady state universe. But science triumphed over philosophical prejudice.
From up close, the cracking sound of a thunderclap dominates. From far away, it's more like a drawn-out rumble. Can science explain why?
Finding this missing piece of water’s path through the universe offers clues to how it came to be on Earth.
We are about to learn a lot more about the most elusive of cosmic particles.
Temperatures in the Sun's core exceed 10 million degrees Celsius. But how on Earth did we actually come to know that?
This beautiful JWST image of Wolf-Rayet star WR 124 has been called a "prelude to a supernova" by NASA. That might be entirely wrong.
2023 is an exciting time for the study of quark-gluon plasmas.
Everything everywhere all at once.
When supermassive black holes merge, they emit more energy than anything else to occur in our Universe except the Big Bang.
We can't go back to the Big Bang, nor ahead to the heat death of the Universe. Nevertheless, here are today's natural temperature extremes.
Even with quantum teleportation and the existence of entangled quantum states, faster-than-light communication still remains impossible.
Not even Einstein immediately knew the power of the equations he gave us.