The word vacuum means suction from higher pressure to lower pressure. The universe is bustling with matter and energy. Even in the vast apparent emptiness of intergalactic space, there’s one hydrogen atom per cubic meter. A barrage of particles and electromagnetic radiation passing every which way from stars, galaxies, and into black holes. There’s even radiation left over from the Big Bang.
So is there such thing as a total absence of everything? It isn’t just a thought experiment. Empty spaces, or vacuums, are beneficial. Inside homes, most vacuum cleaners use a fan to create a low-pressure, relatively empty area that sucks matter to fill the void. But that’s far from empty.
There’s still plenty of matter bouncing around. Manufacturers rely on more thorough, sealed vacuums for all sorts of purposes. That includes vacuum-packed food that stays fresh longer. And the vacuums inside early light bulbs protected filaments from degrading. These vacuums are generally created with some version of what a vacuum cleaner does.
It uses high-powered pumps that generate enough suction to remove as many stray atoms as possible. But the best of these industrial processes tends to leave hundreds of millions of atoms per cubic centimeter of space. That isn’t empty enough for scientists who work on experiments, like the Large Hadron Collider. Here, particle beams need to circulate at close to the speed of light for up to ten hours without hitting any stray atoms. So how do they create a vacuum?
Is space a perfect vacuum?
Gases tend to fill up all available space and get comfortable. That’s usually out to the walls of some solid container like the ISS or like an atmosphere. The gas will expand again to fill lower pressure outside the ISS (International Space Station). Space has this kind of vacuum. But technically, only when there is outer space. Most of the time-space has whatever pressure it has, and there’s no suction. Outer space has lots of matter in it. There’s solar wind zipping out of the Sun, filling the solar system with protons and electrons.
- They’re 5 to 10 protons in every cubic meter of space in the solar system. That’s 82 to 164 protons per cubic inch or 113 to 227 million in the space of a ten-by-ten room.
To make matters worse, there’s also no clear boundary between Earth and space. The air fins out slowly as you go higher and higher. In fact, 57.8% of the atmosphere is under Mount Everest. So there’s not enough air to breathe up there. So There’s no such thing as the vacuum of space.
The LHC’s pipes are made of stainless steel materials that don’t release their molecules. And they are lined with a special coating to absorb stray gases. Raising the temperature to 200 degrees Celsius burns off any moisture, and hundreds of vacuum pumps take two weeks to trap enough gas and debris out of the pipes for the collider’s incredibly sensitive experiments. Even with all this, the Large Hadron Collider isn’t a perfect vacuum.
In the emptiest places, there are still about 100,000 particles per cubic centimeter. But let’s say an experiment like that could somehow get every last atom out. There’s still an unfathomably huge amount of radiation all around us that can pass right through the walls.
- Every second, about 50 muons from cosmic rays, 10 million neutrinos coming directly from the Big Bang, 30 million photons from the cosmic microwave background, and 300 trillion neutrinos from the Sun pass through your body.
It is possible to shield vacuum chambers with substances, including water, that absorb and reflect this radiation, except for neutrinos. Let’s say you’ve somehow removed all of the atoms and blocked all of the radiation. Is space now empty? Actually, no!
All space is filled with what physicists call quantum fields. Subatomic particles, electrons, photons, and relatives are vibrations in a quantum fabric extending throughout the universe. And because of a physical law called the Heisenberg Principle, these fields never stop oscillating, even without any particles to set off the ripples.
They always have some minimum fluctuation called a vacuum fluctuation. It means they have a huge amount of energy. It is because Einstein’s equations tell that mass and energy are equivalent. And the quantum fluctuations in every cubic meter of space have energy corresponding to a mass of about four protons. In other words, the seemingly space inside the vacuum would weigh a small amount.
Quantum fluctuations have existed since the earliest moments of the universe. As the universe expanded, they were amplified and stretched out to cosmic scales in the moments after the Big Bang. Cosmologists believe that these original quantum fluctuations were the seeds of everything we see today:
- Galaxies and the entire large-scale structure of the universe, as well as planets and solar systems.
They’re also the center of one of the greatest scientific mysteries of time. That is because, according to the current theories, the quantum fluctuations in the vacuum of space ought to have 120 orders of magnitude more energy than we observe. Solving the mystery of that missing energy may entirely rewrite understanding of physics and the universe.
Atoms are mainly empty spaces. Empty space is full of quark-and-gluon field fluctuations. On average, it is possible to eradicate a quark from an empty space cause it’s not empty! In fact, to clear out the fluctuations and create a truly empty vacuum would require a lot of energy. The empty vacuum costs an enormous amount of energy to make.
Consider a permanent magnet. It has a magnetic field around it at low energy, at room temperature. The individual little magnetic moments of all the atoms inside are lined up. But if you were to heat it, you would give thermal energy to all those particles. And at a certain point, called the Curie Temperature. They would be so randomly aligned that there would no longer be an overall magnetic field. So it takes energy to get rid of the permanent magnetic field. It is just like the quantum vacuum.
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Chambers, Austin, Modern Vacuum Physics. Boca Raton: CRC Press. ISBN 978-0-8493-2438-3. OCLC 55000526.
Harris, Nigel S., Modern Vacuum Practice. McGraw-Hill.
Billings, Charles E. (1973), “Barometric Pressure,” Bioastronautics Data Book.
Borowitz, Sidney; Beiser, Arthur, Essentials of physics: a text for students of science and engineering, Addison-Wesley series in physics.