All posts tagged: Richard Feynman

Strange Physics: Why Wi-Fi and radio waves can pass through walls but light can’t

Strange Physics: Why Wi-Fi and radio waves can pass through walls but light can’t

Published by Jenni Sidey

A closed door feels absolute. Light stays in one room, darkness settles in the next, and the boundary seems obvious enough to stop thinking about. Yet the same wall that blocks the glow from your kitchen barely slows the Wi-Fi signal drifting through it. That mismatch feels strange for a reason. Visible light and radio waves belong to the same family. They are both electromagnetic waves. They follow the same basic physics. James Clerk Maxwell tied that picture together in the 19th century, and nothing in modern physics has overturned it. So the real puzzle is not why Wi-Fi moves through walls. It is why a wall treats two versions of the same phenomenon so differently. The answer has less to do with the wall being a barrier and more to do with the wall acting like a very selective filter. A popular explanation makes this sound simpler than it is. Radio waves have long wavelengths, people say, so they somehow slip through. Visible light has shorter wavelengths, so it gets blocked. That picture feels …

Physics claims the past and future are identical — so why do we age

Physics claims the past and future are identical — so why do we age

Published by Jenni Sidey

A glass slips from a hand, hits the floor, and bursts into fragments. The sound fades quickly. Heat spreads into the room. Nothing about the scene looks reversible. Yet, in the language of physics, it is. That tension sits at the center of one of the oldest questions in science. The equations that govern motion, energy, relativity, and even quantum behavior do not prefer a direction. Run them forward or backward, they still work. But daily life insists on a different story. Glass breaks but does not rebuild. Coffee cools but never reheats itself. Memory points backward, never forward. You do not wake up younger than you were the night before. Cells wear down. Age accumulates in one direction. No one lives Tuesday, then Monday, then Sunday. In ordinary life, time has a grip. It leaves marks on faces, joints, skin, memory, and muscle. That one-way quality feels so natural that it hardly seems like a mystery until physics says it should not be. Somewhere between clean mathematics and lived experience, time seems to pick …

Einstein claims the past and future are identical – then why do we age

Einstein claims the past and future are identical – then why do we age

Published by Jenni Sidey

A glass slips from your hand, hits the floor, and shatters into pieces. The sound fades quickly. Heat spreads into the room. Nothing about the scene looks reversible. Yet, in the language of physics, it is. That tension sits at the center of one of the oldest questions in science. The equations that govern motion, energy, relativity, and even quantum behavior do not prefer a direction. Run them forward or backward, they still work. But daily life insists on a different story. Glass breaks but does not rebuild. Coffee cools but never reheats itself. Memory points backward, never forward. You do not wake up younger than you were the night before. Cells wear down. Age accumulates in one direction. No one lives Tuesday, then Monday, then Sunday. In ordinary life, time has a grip. It leaves marks on faces, joints, skin, memory, and muscle. That one-way quality feels so natural that it hardly seems like a mystery until physics says it should not be. Somewhere between clean mathematics and lived experience, time seems to pick …

Richard Feynman explains why our night sky is dark despite trillions of stars

Richard Feynman explains why our night sky is dark despite trillions of stars

Published by Jenni Sidey

A black patch of sky looks empty until you stop taking it for granted. That is the starting point of a theory from Professor Richard Feynman, built around what sounds like a child’s question, why the night sky is dark. The usual answer feels obvious. The sun sets, Earth rotates, and night falls. That explains why it is not daytime. It does not explain why the sky itself turns black. For centuries, astronomers and philosophers worked from a set of assumptions that seemed reasonable enough. The universe, they thought, was infinite. It had existed forever. And stars were spread through it more or less everywhere, even if they clustered in galaxies. Put those ideas together, and the darkness overhead starts to look strange. The way into the problem is visual. Picture yourself in a forest so vast it never ends. In a small forest, you can look between trunks and catch glimpses of open sky. In an infinite one, every line of sight eventually hits a tree. Shift your gaze slightly, and you miss the …

If the universe is full of stars then why is the night sky dark?

If the universe is full of stars then why is the night sky dark?

Published by Jenni Sidey

A black patch of sky looks empty until you stop taking it for granted. That is the starting point of a theory from Professor Richard Feynman, built around what sounds like a child’s question, why the night sky is dark. The usual answer feels obvious. The sun sets, Earth rotates, and night falls. That explains why it is not daytime. It does not explain why the sky itself turns black. For centuries, astronomers and philosophers worked from a set of assumptions that seemed reasonable enough. The universe, they thought, was infinite. It had existed forever. And stars were spread through it more or less everywhere, even if they clustered in galaxies. Put those ideas together, and the darkness overhead starts to look strange. The way into the problem is visual. Picture yourself in a forest so vast it never ends. In a small forest, you can look between trunks and catch glimpses of open sky. In an infinite one, every line of sight eventually hits a tree. Shift your gaze slightly, and you miss the …

God and the Quantum Mechanic

God and the Quantum Mechanic

Published by Jenni Sidey

You’d be forgiven for thinking that I am an expert in philosophy. I am only a humble physicist. And while physics can instruct us on the merits of one philosophy over another, it cannot necessarily point us to the right one. It is rather the reverse: Every physicist, deep down, has a philosopher struggling to get out because, without philosophy, we are merely wranglers of equations, slingers of predictions, and collectors of measurement data. Without philosophy, physics is just shutting up and calculating. Now, I love a good calculation, but at the end of the day, to understand what that calculation means, I need philosophy. The philosophy I choose can have vast repercussions on how I interpret findings, what theories I find most appealing, and what direction I want my research to take. In this way, physics is not that different from theology. But whereas theologians have great respect for philosophy, physicists have a tendency to treat it like a waste of time. This is even though all of the most fundamental concepts in physics: …

Death is not the end: What physics says about dying

Death is not the end: What physics says about dying

Published by Jenni Sidey

A flame goes out, and something in the room shifts with it. Not because matter has vanished, but because a structure has ended. The candle’s wax remains, the heat disperses, and the air carries what used to be a steady glow. What disappears is the pattern that held it all together. That same tension sits at the center of how physics approaches death. Richard Feynman returned often to a simple statement in his lectures: everything is made of atoms. It sounds basic until you follow the consequences. Atoms obey strict physical laws. They do not vanish. Energy does not disappear. So when a person dies, the idea of complete erasure runs into a problem. Something ends, but not in the way people tend to imagine. Feynman (center) with Robert Oppenheimer (immediately right of Feynman) at a Los Alamos Laboratory social function during the Manhattan Project. (CREDIT: Wikimedia / CC BY-SA 4.0) A body in motion, not a fixed thing Feynman described a human being less like a solid object and more like a process. The …

Interstellar travel is impossible and aliens haven’t visited Earth, physicists say

Interstellar travel is impossible and aliens haven’t visited Earth, physicists say

Published by Jenni Sidey

“There is a silence in the night sky that has bothered me for as long as I can remember.” Richard Feynman’s reflection lingers because it feels personal. The stars look crowded. Common sense whispers that someone else should be out there. Yet the longer physicists examine the universe, the more that silence appears less mysterious and more structural. Intuition evolved for hunting, shelter, and survival. It did not evolve to grasp light years or relativistic energy. “When you take that human intuition and apply it to the scale of the universe, it doesn’t just fail,” Feynman said. “It snaps.” Five constraints shape that quiet: distance, light speed, propulsion physics, biology, and time. Together they form what Feynman described as “absolute walls that prevent civilizations from ever meeting.” These are not temporary engineering gaps. They are consequences of how reality works. Photo of Richard Feynman, taken in 1984 in the woods of the Robert Treat Paine Estate in Waltham, MA. (CREDIT: Tamiko Thiel 1984 / Wikimedia / CC BY-SA 4.0) A Universe That Refuses to Shrink …

Why interstellar travel is impossible and aliens haven’t visited Earth

Why interstellar travel is impossible and aliens haven’t visited Earth

Published by Jenni Sidey

“There is a silence in the night sky that has bothered me for as long as I can remember.” That observation, attributed to American physicist Richard Feynman, captures a tension many people feel when they look up. The sky appears crowded with stars. Intuition suggests someone else should be out there. However, intuition evolved for survival on Earth, not for interpreting cosmic scales. “When you take that human intuition and apply it to the scale of the universe, it doesn’t just fail,” he said. “It snaps.” The deeper you look at physics, the more that silence starts to make sense. Five separate constraints, distance, light speed, energy, biology, and time, combine into what Feynman described as “absolute walls that prevent civilizations from ever meeting.” These are not merely engineering challenges. They arise from the structure of reality itself. Photo of Richard Feynman, taken in 1984 in the woods of the Robert Treat Paine Estate in Waltham, MA. (CREDIT: Tamiko Thiel 1984 / Wikimedia / CC BY-SA 4.0) A Universe Too Large to Cross Carl Sagan …