When Light Isn’t Enough: How Physics Discovered It Can’t See 95% of the Universe
🔭 Was everything we knew – wrong?
All previous models – from classical physics to the Standard Model – described a world that absorbs and emits light. However, at the beginning of the 20th century, astronomers were faced with facts that caused a revolution in the understanding of the cosmos. It was observed that galaxies were moving faster than they should, and light was bending as if an invisible hand was curving space. The conclusion was inevitable: there exists matter that we cannot see. It does not emit light, does not reflect it, does not interact with anything – except through gravity.
🌌 Dark Matter: The Invisible Skeleton of the Universe
This mysterious matter constitutes ~27% of the Universe. It is not subject to electromagnetism, the weak or the strong force – only gravity. Without it, galaxies would scatter into dust! It is the invisible skeleton holding the cosmos together.
⚛️ Dark Energy: The Greatest Mystery in Physics
At the end of the 20th century, the shock was even greater. It was discovered that the expansion of the Universe is accelerating. This means there is an energy that pushes everything apart – contrary to gravity. It constitutes ~68% of everything that exists and we have named it dark energy. This discovery presented the greatest challenge to modern physics.
🤯 The Greatest Misunderstanding in the History of Science: 10¹²⁰
When physicists tried to unify quantum mechanics (QED) and General Relativity (GR), a collapse occurred. The quantum estimate of vacuum energy (QED) was 10¹²⁰ times larger than the one from GR. If the quantum estimate were true, the Universe would have exploded at the moment of its birth and our reality would not exist.
🔍 Why don’t the theories agree?
QED operates in flat space (Minkowski) and ignores gravity. GR is a theory of curved space – the metric itself is a dynamic variable. Quantum fluctuations cannot simply be forced into a geometric theory because GR assumes a precise distribution of matter to determine the curvature of space. QED starts from the fundamental assumption, best expressed through the Heisenberg uncertainty principle, that this is impossible.
🚀 The Solution? Sought in Quantum Gravity
The two main candidates for a theory of quantum gravity are:
- String Theory – all particles are vibrations of strings in a higher-dimensional space. However, the main problem with this theory is the existence of an additional 6 spatial dimensions, which have not yet been experimentally observed.
- Loop Quantum Gravity – space-time is composed of discrete cells. The problem with this theory is that it predicts a slowing down of high-energy light (e.g., gamma radiation) in a vacuum, which has not yet been experimentally proven.
🌗 Dark Photons: A New Hope?
This year, a revolutionary idea emerged: photons have a dark state – an invisible version that cannot be detected by standard measurements. In the double-slit experiment, the dark fringes could be dark photons. They could explain a part of dark matter and energy. Weak measurement (which does not collapse the wave function) could potentially detect them.
🔮 What’s next?
The path to understanding dark reality is long, but the LHC and future experiments are testing new theories. Dark photons are one of the most exciting hypotheses. Yet, the story is not over…
👉 In the next post:
We will explore light from another angle – a biological one. How do our eyes and brain perceive light? How do we deceive ourselves? Stay with us!
Leave a Reply