Search
Relativity Theory
The idea of gravitational redshift crossed Einstein's mind years before General Relativity was complete. Here's why it had to be there.
Time isn't the same for everyone, even on Earth. Flying around the world gave Einstein the ultimate test. No one is immune from relativity.
Look out at a distant object, and you're not seeing it as it is today. It's size, brightness, and actual distance are all different.
We take for granted that time is real. But what if it's only an illusion, and a relative illusion at that? Does time even exist?
Realism in science cannot be completely unmoored from human experience. Otherwise, realism ends up tortured with unreal paradoxes.
Einstein's theories of relativity faced fierce opposition. One critic claimed he was attempting to subvert the scientific method.
From physics and alchemy to theology and eschatology, Isaac Newton’s research was rooted in a personal pursuit of the Divine.
The Solar System isn't a vortex, but rather the sum of all our great cosmic motions. Here's how we move through space.
Setting resolutions for the new year means you think the future is up to you — but is it?
Even without the greatest individual scientist of all, every one of his great scientific advances would still have occurred. Eventually.
Going to smaller and smaller distance scales reveals more fundamental views of nature, which means if we can understand and describe the smallest scales, we can build our way to […]
Cosmic rays aren’t just limited by the speed of light. Even among non-scientists, it’s well-understood that there’s an ultimate speed limit to the Universe: the speed of light. If you’re a […]
The concept of ‘relativistic mass’ has been around almost as long as relativity has. But is it valid? No matter who you are, where you are, or how quickly you’re moving, […]
It’s 92 billion light-years wide after just 13.8 billion years. And that’s just fine. If there’s one rule that people know about how fast things can move, it’s that there’s a […]
A single lifetime is more than enough to take you to the limits of the Universe. Right now, there are only three things limiting how far our spacecrafts can take […]
It’s fundamentally different from space. Here’s how. Here’s a question that most of us have been asked at some point in our lives, “what’s the shortest distance between two points?” By […]
We might live in a quantum Universe, but we’ll violate the principle of relativity if space is discrete. If you try and divide matter into smaller and smaller chunks, you’ll […]
Scientific surprises are often how science advances. But more often than not, they’re just bad science. When you’re a scientist, getting an unexpected result can be a double-edged sword. The best […]
It’s a pipe dream that violates the laws of physics, and not even quantum mechanics can give us a way out. One of the most fundamental rules of physics, undisputed since […]
Even extremely simple configurations in General Relativity cannot be solved exactly. Here’s the science of why. It’s difficult to appreciate how revolutionary of a transformation it is to consider the Universe […]
It’s been spectacularly confirmed by observation, but theoretically, it couldn’t have been any other way. If the Sun were to spontaneously cease emitting light, we wouldn’t know about it for about […]
You’ve seen a black hole’s event horizon for the first time thanks to them. But they’re only getting started. Earlier this year, 2019, the Event Horizon Telescope collaboration revealed the first […]
It’s perhaps the most famous equation of all, with lessons about reality for every one of us. If you’ve ever heard of Albert Einstein, chances are you know at least one […]
Particle physics is everywhere, even in the palm of your hand. When you hold out your palm and point it towards the sky, what is it that’s interacting with your hand? […]
The laws of physics are not time-reversal invariant. Here’s how we know. No matter when, where, or what you are in the Universe, you experience time in only one direction: forwards. […]
If you think nothing can move faster than light, check out this clever way to defeat that limit. Nothing can move faster than the speed of light. When Einstein set forth […]
And why Einstein’s quest for unification was doomed from the start. If you wanted to answer the question of what’s truly fundamental in this Universe, you’d need to investigate matter and […]
A single thought experiment reveals a paradox. Could quantum gravity be the solution? Sometimes, if you want to understand how nature truly works, you need to break things down to […]
If you think you have problems today, be glad you’re not moving at the speed of light. Special relativity, even though it’s over 100 years old, is still one of the […]
Einstein’s explanation is the only one that works. When Newton first proposed the law of universal gravitation, it marked the very first time that we realized the same rule governing how […]