December 9, 2017
Zayan Guedim
This is the second part of our two-part series on physics mysteries that scientists have yet to solve.
While our knowledge of the Universe has progressed considerably in recent years, there are still many outstanding questions that need answers.
And, no, it’s not 42!
If you haven’t read the first 10 Unanswered Questions, you can check them out here. Then come back for part 2–or you can do it backward, it’ll still be mysterious.
11. Black Hole Information Paradox
Black holes are the last stage in the life cycle of massive stars that are much bigger than the Sun. Our home star, which has already used up about half of its fuel, will eventually collapse into a white dwarf.
The Milky Way alone is riddled with ten million to a billion black holes, including a recently discovered monstrous one.
As cold relics of giant stars, black hole existence isn’t what puzzles scientists. It’s what’s called the Information Paradox that really gets the gears turning.
According to the theory of relativity, information (objects) that fall into a black hole are annihilated forever. However, quantum physics says that quantum information can’t be destroyed. Thus, anything that passes a black hole’s event horizon could still be retrieved.
However, a new type of wormhole could help solve the Information Paradox. Two researchers at Harvard and Stanford University published a study about “Traversable Wormholes” that would allow information to escape black holes.
12. Naked Singularities
At the center of a black hole lies what’s called a “singularity”, an infinitesimal point where all the matter of the black hole is concentrated. Around the singularity is a spherical region, known as the event horizon, beyond which no object (information!) can escape, not even light.
An object that crosses the event horizon is believed to never come out (unless it falls into a traversable wormhole?)
A “naked singularity” is a gravitational singularity that’s not hidden behind the event horizon, and thus could be observed.
According to mathematical simulations, naked singularities were thought to exist only in a five-dimensional universe, but it may be that these strange objects do exist in a three-dimensional universe [Physical Review Letters] like ours, as theoretically proved recently by Cambridge researchers.
13. CP Symmetry Violation
In particle physics, CP symmetry (charge conjugation parity symmetry) refers to the consistency of physics laws when a particle is inverted to its antiparticle.
In 1964, James Cronin and Val Fitch found CP violation in some radioactivity reactions, a discovery that earned them the Nobel Prize in Physics in 1980.
Scientists, however, still don’t understand why and how certain particles violate the CP symmetry.
14. Sonoluminescence: How Does Sound Create Light?
Sound and light are two phenomena that involve waves, and which are fundamentally different physically speaking, yet there is another amazing phenomenon that links them in a strange way.
Sonoluminescence can be demonstrated using simple setup. If you direct sound wave into a container filled with water, bubbles will form then collapse, emitting short bursts of light in the process.
Where does this light come from? How does the energy of sound waves get converted into light? Tiny nuclear reaction? Gas heating?
15. What is Gravity Anyway?
Unlike the other three fundamental forces, gravity can’t be quantized and has been measured until today only at higher scales.
While the theory of general relativity has succeeded in describing the force of gravity over cosmological distances, it has not been tested in the microscopic realm.
This is the subject of quantum gravity theory, which suggests the existence of gravitons, massless particles that remain theoretical at the moment, as no one has managed to detect this quantum messenger of gravity.
Yet, there’s hope. The Higgs-Boson Particle had also only existed theoretically since the 1960s, within the Standard Model, until it was finally detected in 2012 by CERN’s Large Hadron Collider.
16. Are we in Trouble Inside the “False Vacuum”?
The universe is about 14 billion years old, so that might indicate that it’s relatively stable.
We know that there empty zones in space, but it is not an absolute void because it is unstable. It is constantly stirred by virtual particles that are created and annihilated permanently.
The Higgs-Boson mentioned above is a particle that gives matter its mass via what’s called the Higgs field–an invisible force that however has a very observable effect.
So, the vacuum might not be the lowest possible energy state, and some kind of vacuum energy should be at play. Here comes the “false vacuum” theory, which suggests that the universe might not be stable after all.
Could that mean that a high-energy event could knock this false vacuum into a lower energy state and trigger a “false vacuum bubble” that would annihilate all matter in its way?
But then again, the universe, as we already said, has been around for a long time, witnessing violent cosmic events, and we’re still here. So, with luck, we might be safe from such a demise.
17. “Dimensionless” Fundamental Physical Constants
The mathematical formulas used in physics define relations between physical quantities, which have dimensions, thus can be measured using certain units.
A physical constant is a physical quantity whose numerical value is fixed, like the speed of light.
However, dimensionless constants don’t depend on a units system, and so their value is important to describe the nature of the physical world.
The most known is the fine-structure constant but there are at least 26 dimensionless fundamental physical constants in the Standard Model.
And that leads us to our last problem.
18. The Standard Model Limits
The universe and everything therein seems to be made of fundamental particles obeying is the four fundamental forces: electromagnetism, the weak interaction, the strong interaction, and gravity.
The Standard Model of particle physics is the current theory that explains all observable phenomena, encompassing all known particles.
A theory that is both quantum and relativistic, the standard model has helped, since the early 1970s, make precise predictions time and time again. However, this model can’t explain everything.
For starters, it incorporates only three out of four interactions (fundamental forces) having a particle-scale effect, because gravity is still resisting theoreticians.
The Standard Model can’t provide definitive answers to the 17 questions we’ve covered in our two-part series and remains in itself an unsolved problem.
See the full article here .
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