Want to ask something?
Send us an e-mail with the subject “Physics mysteries” to the address:
We can't wait to tackle your interesting questions!
Did the dinosaurs measure the half-life?
How have we measured half-lives that are millions and millions of years for some isotopes? After all, the discovery of radioactivity and the Geiger counter is less than two hundred years old so did th ...
The ability of dinosaurs to construct radiation detectors, take measurements, and record the results has not yet been proven, and it is quite likely that they did not actually do any such thing. Yet we know the half-lives of elements that are longer than the time that dinosaurs ruled the Earth.
In order to explain how this is possible, it is first necessary to clarify what the half-life is ...
Do photons know the future?
While reading a text on the refraction of light, I came across the disturbing formulation “light chooses the fastest path” ...
Photons are particles with zero rest mass moving in a vacuum at the speed of light. As bosons, they are not constrained by the Pauli Exclusion Principle and can pass through each other or occupy the same quantum state ...
Elements from the island of stability
Is the periodic table of elements finite or are there other elements in the universe that we haven’t discovered yet? Do we have any idea what properties they might have? Could aliens make spaces ...
The nucleus of each atom is made up of protons with the addition of more or less neutrons. It is thus theoretically possible for an element to exist with any number of protons in its nucleus. Perhaps a thousand or a million. But protons, as charged particles, repel each other, and the more there are in the nucleus, the harder it is to keep the nucleus together ...
Where does the “first neutron” that starts a fission chain reaction in a nuclear reactor come from?
The fission chain reaction in a nuclear reactor takes place when a neutron flies to a uranium-235 atom and collides with it, splitting the nucleus into two or three fragments. Several neutrons fly out of the whole process, slow down appropriately, collide with other uranium atoms, and so on. Each fission of uranium generates neutrons, which cause other uranium nuclei to fission ...
Why are people crowding in the hall and not in the door through which they go out?
When we are leaving the concert hall, a terrible crowd and pushing forms. But once we’re in the doorway, where it’s the narrowest and people should therefore be pushing the hardest, the sp ...
You may not like it, but people crowding outside the exit of a concert hall are subject to the Venturi effect. The same physical principle applies to water flowing through a pipe or wind blowing through a canyon.
The fluid flowing through a pipe must obey the laws of conservation of energy. The total energy of the fluid, i.e ...
Could two photons collide?
The short answer is yes, they can, but it is extremely unlikely.
Photons are quanta of electromagnetic waves. When you turn on a light bulb, it starts producing billions and billions of these particles that whizz through your living room at the speed of light. They’re pure energy. They have no rest mass. Photons are a type of quantum particle called bosons ...
In the event of a nuclear apocalypse, can I somehow build a radioactivity detector out of the stuff in my pockets?
Hopefully, it will never be necessary. To answer your question, let’s first look at what radioactivity is, and how it is measured.
Radioactivity is the process by which unstable atoms produce ionising radiation. This radiation can also reach us from space, where it is produced by stars and dramatic processes in the cores of galaxies. Ionising radiation is divided into several types ...
I peeled off the adhesive tape in total darkness and a bluish light appeared. What happened?
By quickly peeling off the adhesive tape, you not only caused a flash of visible light, but even a brief pulse of X-rays. Don’t worry, you are not in any danger and you can keep using the tape.
This phenomenon is called triboluminescence. In some substances, the mechanical energy to which they are subjected, say during crushing or scrubbing, is converted into its internal energy ...
From a safety point of view, could a collision of 1 mg of H-H produce neutrons, T, D and beta radiation?
In a container filled with hydrogen under normal conditions, i.e. at room temperature and atmospheric pressure, hydrogen molecules (H-H, H2) collide quite normally. However, nothing at all is formed — only their temperature and momentum change as they collide.
In order for hydrogen to become a different isotope, a change must occur in its atomic nucleus ...
Why can a swallow sit on a wire?
There are signs on power poles saying it is dangerous to climb up and touch the wires. In the media I can find frightening stories of people who have climbed up to the wires and been killed or mu ...
Depending on the distribution power lines of the country in which the bird lives, it can choose to sit on lines with a voltage of 100—400 kV, in some parts of the world even up to 800 kV. Electricity with such a high voltage has low transmission losses and is easier to transport over long distances from power plants to cities and factories. Here it is transformed to lower voltages ...
Does lightning always have to strike the ground?
The most common way to draw lightning is a zigzag line from the cloud to the ground. However, this is not the only way lightning can strike. This relates to the rather complicated way in which lightning is produced in a storm cloud.
Even though it is made up of only water, a storm cloud is a huge structure, ranging from a few kilometres above the ground to 12 kilometres up ...
Water is said to have been brought to Earth by comets. But where did the water in space come from?
Water is a compound of hydrogen and oxygen. A water molecule contains one oxygen atom and two hydrogen atoms bonded to it at an angle of 104.45 degrees. In order for water to appear in the universe, these two basic elements had to be present first.
Hydrogen was created at the very beginning of the universe ...
Can anything be lighter than hydrogen?
At the carnival, we can buy helium-filled balloons that float because helium is lighter than air. If hydrogen balloons were available, they’d be even lighter, but hydrogen is explosive, so it&rs ...
Hydrogen is the lightest element in the known universe. It consists of just one proton orbited by a single electron. It would seem, therefore, that nothing could be lighter.
Theoretically, it would be possible to create an artificial element from subatomic particles, for example muonium ...
Is it possible that aliens have visited the Earth in history?
Some materials or products are said not to be “earthly”.
It’s certainly possible, but I’m not aware of any irrefutable evidence for it.
Astronomers are convinced that there must be more than 1 planet in the universe to support life as we know it (which is understandable with billions of star systems) ...
What is done with used wind turbine blades?
Even green power plants eventually run out of life, and I can’t imagine how such a hundred-metre blade from a wind turbine is carried to the scrap yard… What is actually done with th ...
Wind turbine blades are made of composites, fiberglass or carbon fibre, strengthened together with polymeric resin. They are designed to withstand harsh natural conditions. Strong winds, rain, frost, and ultraviolet radiation from the scorching sun. This is definitely not a material that can be easily destroyed. But even so, they have a lifespan of about twenty years ...
Is a hammer or a feather lighter?
If I drop a hammer and a feather on the moon at the same time, as astronaut David Scott did in the famous video, they will fall simultaneously ...
All bodies in the Earth’s gravitational field are subject to a gravitational force that gives them the same gravitational acceleration g. If nothing obstructed the bodies when falling, they would all accelerate equally and therefore any pair of simultaneously dropped bodies would hit the ground at the same moment. Just as the feather and the hammer fell at the same moment on the moon ...
Is there a place on the Earth where a person ages faster or slower (very deep underwater or very high in the mountains, etc.)?
I imagine the place where I am on holiday is such a place :D But if we tried to answer this question purely from the physical point of view, there is no place on Earth where we would age noticeably slower ...
Is it possible to teleport yourself or at least something?
We mean the immediate movement of anything to any place by teleportation which we know from Star Trek, for example.
The problem I see is mainly that we want to move anything and immediately.
Every highlighted word alludes to the laws of physics — “anything” to quantum physics and “immediately” to the theory of relativity ...
Is it possible to travel in time?
So far it seems that time travel is limited by causality — this means that the effect can never precede the cause — I can’t be full before I start eating.
Therefore, travelling to the future is real, but it is a one-way journey ...
Is there energy left in the world after a person dies?
In the physical sense, certainly yes, in the philosophical sense, maybe also and whether in the metaphysical sense, I don’t know.
Since we are composed of carbon, oxygen and water, it would be possible to extract these elements from the body and use them, for example, in combustion or nuclear fusion ...