Physics Concepts Explainer

In physics, even geniuses can be wrong. For decades, many physicists believed that hidden-variable theories had been mathematically ruled out by John von Neumann's famous 1932 proof. The conclusion seemed definitive: quantum mechanics could not be completed by introducing deeper variables beneath the wavefunction. Then came John Bell. Bell carefully examined von Neumann's proof and found something remarkable. The mathematics was correct, but one of the key assumptions was not physically justified. Von Neumann had assumed a particular relationship between the values of observables even for quantities that cannot be measured simultaneously. Bell's criticism was devastating: the proof did not rule out all hidden-variable theories. It ruled out only a specific class of them. And history vindicated Bell. In 1952, David Bohm constructed a fully deterministic hidden-variable theory that reproduced all the predictions of quantum mechanics. Such a theory should have been impossible if von Neumann's no-hidden-variables theorem had truly been general. Bell's deeper achievement was not merely finding a flaw. He went further and proved something far more profound. Through Bell's theorem, he showed that any hidden-variable theory reproducing quantum predictions must be nonlocal in a very specific sense. So the question was never simply: "Von Neumann or Bell?" The real story is subtler. Von Neumann showed that one natural class of hidden-variable theories fails. Bell showed that nature had not exhausted all possibilities and that the real price of hidden variables is nonlocality. That shift transformed the foundations of quantum physics. A reminder that science advances not by worshipping authorities, but by examining assumptions. Source : Ayus Cosmological

AI field note: In 2025, AWS data centers used 0.12 liters of water per kilowatt-hour, over 7x more water-efficient than the industry average of 0.84. That efficiency improved even as AI pushed compute demand higher. Here's how we did it.   Cooling a data center presents a three-way tradeoff: water use, energy use, and the temperature margin that keeps servers reliable. Push hard on one and pressure shows up somewhere else. Cool with little energy and you use more water. Cool with little water and you spend more energy on chillers, which draw 25 to 35% more electricity, often when the grid is most stressed. Keep both water and energy low and the servers run warmer, closer to their limits.   We asked if the cooling threshold we had treated as fixed actually had room to move. If the system can operate safely at a higher threshold before water-assisted cooling kicks in, you can keep water and energy low without sacrificing reliability.   So we tested it. Thousands of hours of operational data across campuses showed we could safely raise that threshold, within tested operating conditions, without increasing failure rates. Water-assisted cooling now starts only around 85°F. About 90% of the time, the data centers cool with outside air alone.   The results hold at scale, not just per unit of compute. In Northern Virginia, our largest region by load, water use fell 42% in a year while capacity grew. Across the sites we own and operate, total water withdrawn fell 2% from 2024 to 2025, even as the number of buildings rose. As per-unit efficiency improved, total use went down.   On the hottest hours, when air alone isn't enough, the systems use a small amount of evaporative water rather than switching to chillers that would spike electricity demand when the grid can least absorb it. A little water during peak heat is a lower total burden on the surrounding community than a lot of electricity at the same moment.   The savings for our most common data center designs came from a lot of systems innovation, and from proving that a constraint we'd long accepted as fixed could actually move. In this era, a lot of fixed constraints are worth re-testing.

Data centers now use 415 TWh of electricity a year. By 2030, that could hit 945 TWh. Cooling alone eats 30–40% of that energy. Fans and air can't keep up with AI chips anymore. Some are looking up. Google, NVIDIA, and startups like Starcloud are exploring data centers in orbit—where solar power is constant and the vacuum of space offers free cooling. No fans. No water. But the hurdles are steep: launch costs, radiation damage, latency, and radiators the size of buildings. Behnood Bazmi looked down instead. A grad student at the University of Illinois, he wasn't chasing AI. He was studying heat. And he kept asking one question: what if cooling is the real bottleneck? His team used algorithms to design copper cooling plates no engineer would sketch. Jagged, branching fins just 30–50 micrometers thick—thinner than a human hair. Too complex for machining. Too intricate for most 3D printing. Then they partnered with Fabric8Labs to build them using electrochemical additive manufacturing at room temperature. What they measured: ↳ 32% lower thermal resistance ↳ 68% less pumping power ↳ Cooling energy drops from ~550 MW to 11 MW in a 1 GW facility ↳ 98% less energy spent keeping chips cool Space data centers may come. But this works now—on Earth, at lab scale, with a path to manufacturing. Sometimes the answer isn't a moonshot. It's a grad student asking a question everyone else stopped asking. 1 question about heat. 10 researchers bridging design and manufacturing. 100 data centers running on a fraction of the energy. What problem have you stopped questioning because it felt too obvious? Follow me, Dr. Martha Boeckenfeld, for insights on thriving as AI rises while leaders stay human. Sources: IEA, Cell Reports Physical Science (May 2026), UIUC, Fabric8Labs https://lnkd.in/euNCgcGg

 Quantum Embezzlement: Physicists Discover a Potential Infinite Source of Entanglement In a groundbreaking study, theoretical physicists have mathematically demonstrated that quantum embezzlement—a process initially described as a thought experiment—could theoretically provide an infinite source of quantum entanglement without disrupting the fragile states involved. What is Quantum Embezzlement? - Originally described by Wim van Dam and Patrick Hayden in the early 2000s, quantum embezzlement refers to the ability to extract entanglement from a quantum system without altering its overall state.   - It’s akin to "stealing from a quantum bank account" where the transaction leaves no detectable trace—it’s the perfect quantum crime.   - In this context, entanglement serves as a critical resource for quantum computing, encryption, and communication systems.  Theoretical Breakthrough Physicists Lauritz van Luijk, Alexander Stottmeister, Reinhard F. Werner, and Henrik Wilming from Leibniz University Hannover in Germany have pushed the boundaries of this concept: - Using algebraic techniques combining general relativity and quantum field theory, they demonstrated that a relativistic quantum field could theoretically act as an infinite reservoir of quantum catalysts.   - These catalysts could entangle quantum systems without altering their observable properties, enabling repeated entanglement without diminishing the original resource.   - Mathematically, the quantum "bank" remains in the same state before and after the entanglement process—rendering the “crime” undetectable.  Lauritz van Luijk explains, "Since the bank is in the same state before and after the embezzlement, that means no one can detect it. It's the perfect crime." Why Entanglement Matters Quantum entanglement is the backbone of technologies like: 1. Quantum Computing: Enabling exponentially faster computations.   2. Quantum Cryptography: Ensuring secure communication channels.   3. Quantum Teleportation: Allowing data transfer without physical movement of particles.  Entanglement is also notoriously fragile. Even the slightest interference can collapse its delicate balance, rendering it useless. The concept of infinite catalytic entanglement—if practically realized—could solve one of the biggest bottlenecks in scalable quantum systems.  How Does it Work? - Quantum states operate under rules dictated by quantum mechanics.   - These states can be described mathematically as wave functions, which represent probabilities rather than definite values.   - Through quantum embezzlement, a catalyst state allows two particles to become entangled without consuming or disrupting the catalyst itself.   - The recent mathematical findings suggest that quantum fields—as described by relativistic quantum field theory—could naturally act as infinite entanglement sources.  

𝐈𝐧 𝐭𝐡𝐢𝐬 𝐩𝐨𝐬𝐭 𝐈’𝐝 𝐥𝐢𝐤𝐞 𝐭𝐨 𝐞𝐱𝐩𝐥𝐚𝐢𝐧 𝐭𝐡𝐞 𝐝𝐢𝐟𝐟𝐞𝐫𝐞𝐧𝐜𝐞𝐬 𝐛𝐞𝐭𝐰𝐞𝐞𝐧 𝐭𝐡𝐞 𝐭𝐲𝐩𝐞𝐬 𝐨𝐟 𝐞𝐥𝐞𝐜𝐭𝐫𝐢𝐜𝐚𝐥 𝐩𝐨𝐰𝐞𝐫. In electrical systems, we commonly talk about three kinds of power: apparent power, active (real) power, and reactive power. 𝐀𝐩𝐩𝐚𝐫𝐞𝐧𝐭 𝐏𝐨𝐰𝐞𝐫 (𝐒): This represents the total power that a system appears to use. It is the product of voltage and current, without considering the phase angle. The formula is: S = V × I Apparent power is measured in VA (volt-amperes). For example, a generator might be rated at 1000 kVA. 𝐀𝐜𝐭𝐢𝐯𝐞 𝐏𝐨𝐰𝐞𝐫 (𝐏): Also known as real or true power, this is the power actually consumed by the system to perform useful work—such as running motors or lighting. Due to inefficiencies and phase differences in real systems, active power is always less than apparent power. The formula is: P = V × I × cos(φ) It is measured in W (watt). For instance, the same 1000 kVA generator might supply around 900 kW of active power. 𝐑𝐞𝐚𝐜𝐭𝐢𝐯𝐞 𝐏𝐨𝐰𝐞𝐫 (𝐐): This type of power doesn’t do any real work but is essential for sustaining electric and magnetic fields in inductive and capacitive components (like motors and transformers). It’s calculated with: Q = V × I × sin(φ) Reactive power is measured in VAR (volt-ampere reactive). Based on the previous example, the generator that supplies 1000 kVA of apparent power and 900 kW of active power would have approximately 435 kVAR of reactive power (using the power triangle formula). These three powers are related by the power triangle, which is represented by the following equation: S² = P² + Q² What is Power Factor? Power Factor (PF) is the ratio of active power (P) to apparent power (S): Power Factor (PF) = P / S = cos(φ) φ (phi) is the phase angle between the voltage and current waveforms. A smaller φ means a better power factor and a more efficient system.

Black holes may not erase information at all. They may process it. Our new work on spacetime and quantum information is now published in IOP Publishing Journal of Physics A: Mathematical and Theoretical. The paper explores a picture in which the edge of a black hole is not silent darkness, but an active quantum-information interface. In this extension to our QMM work, the horizon briefly stores fragments of infalling quantum information, scrambles them, and slowly releases them back into the outgoing radiation through subtle echoes and correlations. Using fully unitary simulations of near-horizon dynamics, we observe Page-curve-like behavior, delayed information retrieval, and structured entanglement patterns that resemble a black hole whispering back traces of what it consumed. Link to paper: https://lnkd.in/gTvcskvP Terra Quantum AG, Leiden University #QuantumPhysics #QuantumInformation #BlackHoles #QuantumGravity #Entanglement #HawkingRadiation #TheoreticalPhysics #Physics #Cosmology #GravitationalWaves

I updated my Schrödinger equation visuals. This time I included the unbounded inner product Gaussian in the first 2 animations, and used the more familiar localized inner product on the last. To review: The Schrödinger equation is one of the cornerstones of quantum mechanics, describing how the quantum state of a physical system changes over time. Here's a detailed explanation without using any equations: ### **Core Idea:** The Schrödinger equation governs the behavior of quantum systems, much like Newton's laws govern classical mechanics. Instead of predicting exact positions and velocities of particles, it tells us how the *probability amplitude* (a complex-valued function related to the likelihood of finding a particle in a certain state) evolves over time. ### **Key Concepts:** 1. **Wavefunction (ψ):** - In quantum mechanics, particles don’t have definite positions or paths. Instead, their state is described by a *wavefunction*, which contains all the probabilistic information about the system. - The wavefunction doesn’t tell us where a particle *is* but rather where it *might be* and with what probability. 2. **Time Evolution:** - The Schrödinger equation explains how the wavefunction changes with time. It doesn’t determine a single outcome but describes a smooth, deterministic evolution of probabilities. - If you know the wavefunction at one moment, the equation tells you how it will look in the next instant. 3. **Energy and Hamiltonian:** - The equation depends on the *Hamiltonian*, which represents the total energy of the system (kinetic + potential energy). - Different potentials (e.g., an electron in an atom vs. a free particle) lead to different wavefunction behaviors. 4. **Superposition & Quantization:** - The equation naturally leads to *superposition*—where a quantum system can exist in multiple states at once until measured. - For bound systems (like electrons in atoms), it predicts *quantized* energy levels, explaining why electrons occupy discrete orbitals. 5. **Uncertainty & Probabilities:** - The wavefunction’s square magnitude gives the probability density of finding a particle in a certain state. - Unlike classical physics, quantum mechanics is inherently probabilistic, and the Schrödinger equation encodes this randomness. ### **Analogy (Rough but Helpful):** Imagine a ripple spreading on a pond. The shape and motion of the ripple depend on the water’s properties (like depth and obstacles). Similarly, the Schrödinger equation describes how the "quantum ripple" (the wavefunction) evolves based on the system’s energy landscape. ### **Interpretations:** - The equation itself doesn’t explain *why* the wavefunction behaves this way or what it "really" is—that’s the realm of quantum interpretations (e.g., Copenhagen, Many-Worlds). #quantum #quantumphysics #quantummechanics #physics #math #engineering #programming #Schrödinger #science

In the well-known double-slit experiment, electrons exhibit wave-like behavior when not being measured, producing an interference pattern on the detection screen. But when we attempt to determine which slit an electron goes through, that pattern disappears, and the electrons behave like particles. This shift is not due to electrons “knowing” they’re being watched. Instead, it’s a fundamental consequence of quantum measurement. According to quantum mechanics—specifically the Copenhagen interpretation and the uncertainty principle—observing a quantum particle requires interaction. To detect an electron’s path, we use photons, which carry energy. Since electrons are extremely small, even a single photon can significantly disturb their motion or momentum, effectively collapsing their wave function into a definite state. This collapse destroys the superposition—the state where an electron exists in multiple possible paths—and eliminates the interference pattern. The act of measurement turns a probability wave into a single, classical outcome. This isn't mysticism or magic. It's a well-documented quantum phenomenon with decades of experimental support. Measurement affects quantum systems—not because of observation in the human sense, but because of unavoidable physical interaction. It's not magic. It's quantum physics.

Bell’s Inequality: Where Physics Breaks Common Sense Bell’s inequality asks a fundamental question: Is reality both local and pre-determined? Local → no influence travels faster than light Realistic → physical properties exist before measurement This aligns with Einstein’s intuition: "The moon is there whether we look at it or not." John Bell formalized this into a test: If the world is local and realistic, then measurement correlations must obey a strict bound known as Bell’s inequality. However, experiments consistently violate this bound. This leads to a profound conclusion: At least one assumption must fail: Locality Realism Quantum mechanics resolves this tension by abandoning classical realism. A simple analogy: Classical world → outcomes are fixed in advance Quantum world → outcomes emerge only upon observation Bell’s theorem shows that reality is not just unknown before measurement. It may not even exist in a definite form.