Recent content by Tiago

Hi, We all know the universe is expanding and it's doing so at a rate greater than the speed of light. But what does expansion mean? Popular Science videos usually give the loaf of bread example expanding in the oven. But even the loaf of bread has limits, it can only expand so far. Do we know...

Hello, Let me explain my question. We know from GR, that gravity is just something (planet, light, etc) following a geodesic path through distorted spacetime. But that's just because everything is still in motion from the big bang, traveling at the speed of its own inertia. So let's assume...

Don't worry, it's probably me that's not explaining myself in the best way. My point was, if the Earth is traveling at different speeds according to different IRF's, it also means that it's traveling at different % of c. According to the Sun it might be traveling at 10% the speed of light...

Ok, but what do we mean when we say that Earth is traveling at 10% the speed of light? How do we even measure that? Earth is traveling at different speeds according to different IRF's, right?

So, from what I understand, all it matters is what speed everything "else" is traveling relative to light. If Earth is traveling (for example) at 10% the speed of light and the Sun is traveling at (again, an example) at 15% the speed of light, there is a ratio here that we can mathematically...

So to go back to my initial question, Stephen Hawking says that a good way to travel to the future would be to go on a rocket and travel very close to the speed of light and come back to Earth in a few years (ok, so far so good). But when he says "travel very close to the speed of light", we'd...

Ok, but if I'm going close to the speed of light for 10 years, when I'd return to Earth, 20 years (or so) would have passed and I only aged 10. So time went slower for me than time of people on Earth. What's confusing me is at what speed should I go to do that. Einstein says it should be very...

Hi, We know that gravity affects time and the presence of big masses such as planets will cause big distortions in spacetime which slows things down (if I'm floating in space, won't I be distorting spacetime for.. say.. an ant? Won't the ant gravitate towards me?). Anyway. we know that...

Knowing that it's off subject here, but there is something else that's been mindblowing me. Of course we know that gravity affects time and the presence of big masses such as planets will cause big distortions in spacetime which slows things down (if I'm floating in space, won't I be distorting...

Ok, it makes sense. It's basically an adaptation of Einstein's Special Theory of Relativity, right? It doesn't really matter if the ground hits the person or if the person hits the ground, it all depends on reference frame. Still, if a person jumps of a building and an external observer is on a...

I'm going to risk bringing a different subject that I think relates to everything we've been talking about. Of course, before Einstein, gravity according to Newton was much easier to understand. And in some websites, people will still say that gravity is a force that pulls to the center of the...

Is this video accurate on ilustrating GR?

I think what makes it confusing (at least for me) is understanding the principle of equivalence. Of course it's easy to understand why a person would feel an artificial gravitational field if traveling upwards on a rocket in empty space. I would feel the force of the acceleration of the rocket...

Of course I probably understand the idea behind what Brian Greene explained, but not the complexity of its concepts. And it's good that I don't, cause I'm not a physicist, I'm merely someone that admires physics, live fascinated by it and largely because of enthusiasts like Brian Greene that...

I understand what you're saying about the rolling balls on rubber sheet, but have you seen the Elegant Universe by Brian Greene? He actually explains the GR, not quite like rolling balls on a rubber sheet but he does say that the distortion of spacetime caused by the presence of a large mass...