Messing around with people once more :p (can’t swear it will be the last omegle chat log)

Physics Blog
All about Physics

“Imagine that we could constantly accelerate at the same rate as Earth’s gravitational pull, 9.8 m/s

^{2}, indefinitely. While you’d initially speed up, you’ll rapidly approach the speed of light.Owing to Einstein’s Special Relativity, time will dilate and lengths will contract. As you continue to accelerate, the distances and travel times to faraway destinations will plummet.

At the halfway mark, simply reverse your thrust to accelerate in the opposite direction for the remaining journey.

“

If you wanted to travel to a star that was 100 light-years away, you might think it would take you at least 100 years to get there. That might be true from the perspective of someone who remains on Earth, but for an astronaut who journeyed there at close to the speed of light, Einstein’s Special Relativity tells you that it would take far less than a century of travel. In fact, if you could accelerate at a constant rate, you could pretty much reach anywhere you wanted within 15 billion light-years of us within a human lifetime.

“Imagine that we could constantly accelerate at the same rate as Earth’s gravitational pull, 9.8 m/s

^{2}, indefinitely. While you’d initially speed up, you’ll rapidly approach the speed of light.Owing to Einstein’s Special Relativity, time will dilate and lengths will contract. As you continue to accelerate, the distances and travel times to faraway destinations will plummet.

At the halfway mark, simply reverse your thrust to accelerate in the opposite direction for the remaining journey.

“

If you wanted to travel to a star that was 100 light-years away, you might think it would take you at least 100 years to get there. That might be true from the perspective of someone who remains on Earth, but for an astronaut who journeyed there at close to the speed of light, Einstein’s Special Relativity tells you that it would take far less than a century of travel. In fact, if you could accelerate at a constant rate, you could pretty much reach anywhere you wanted within 15 billion light-years of us within a human lifetime.

“If the Universe had a frame of reference that was distinct from all the others, then there should be some measurement you could make that revealed to you how the laws of nature were different when you moved at one particular speed in one particular direction. But that is inconsistent with the Universe we have. No matter how fast you move or what direction you move in, the laws of physics are the same, and any physical experiment you can perform will give the same measurable results and result in the same physical phenomena.”

When we think about Einstein and the principle of relativity, we normally talk about the Michelson-Morley experiment, which showed that the speed of light remained constant whether it was aligned with or at an angle to Earth’s motion. We might think about the Lorentz transformations like time dilation or length contraction. Certainly, those results played a role, but Einstein himself was thinking about a puzzle that came to light much earlier: about what’s physically occurring to cause Faraday’s law of induction. If you move a bar magnet into a stationary coil of wire, you generate an electric current. If you move a coil of wire onto or off of a stationary bar magnet, you also generate an equal intensity electric current. But the physics of how is entirely different!

“The Universe is not simply made of point masses, but of complex, intricate objects. If we ever hope to tease out the most sensitive signals of all and learn the details that elude us today, we need to become more precise than ever. Thanks to three-atom interferometry, we can, for the first time, directly measure the curvature of space.

Understanding the Earth’s interior better than ever is the first thing we’re going to gain, but that’s just the beginning. Scientific discovery isn’t the end of the game; it’s the starting point for new applications and novel technologies. Come back in a few years; you might be surprised at what becomes possible based on what we’re learning for the first time today.”

Go out and measure how an object falls: that gives you gravitational acceleration. Go out and measure how that falling is different between two locations identical in every way except at different elevations, and you’ll measure a gravitational gradient, sufficient for telling Einstein’s theory apart from Newton’s. But if you can measure the differences in gravitational acceleration between three locations at once, you can measure changes in that gradient, and come away with an understanding of spacetime curvature.

“Given the equation for gravity between two masses, and the fact that photons are massless, how is it possible for a mass (like a star or a black hole) to exert influence on said photon?”

You know the law of universal gravitation: you put in what any two masses are, how far apart they are from each other, and the gravitational constant of the Universe, and you can immediately know what the force is between any two objects. Set one of the masses to zero, and the force goes to zero. So why is it, then, that if you take the ultimate particle with no mass, a photon, and pass it close by a mass, its path does bend? Why do massless particles experience gravity?

To understand why, you should think about what happens if you and I start at the same place near a mass, but I’m stationary and you’re moving. How far away is that mass? What’s the “r” that goes into Newton’s equation? And who’s right: me or you?

“When the lens and a background source align in a particular fashion, quadruple images will result. With slightly different light-travel paths, the brightness and arrival time of each image is unique. In November 2014, a quadruply-lensed supernova was observed, showcasing exactly this type of alignment. Although a single galaxy caused the quadruple image, that galaxy was part of a huge galaxy cluster, exhibiting its own strong lensing effects. Elsewhere in the cluster, two additional images of the same galaxy also appear.”

We normally think of light traveling in a straight line, but that’s only true if your space is flat. In the real Universe, mass and matter not only exist, but clump together into massive structures like galaxies, quasars, and galaxy clusters. When a background source of light passes through these foreground masses, the light can get bent and distorted into multiple images that are magnified and arrive at slightly different times. If an event occurs in one such image, we can predict, based on General Relativity, cluster dynamics, and dark matter, when that event will appear in the other images.