Tag Archives: vacuum

Writing prompt: create a vacuum day

Time: 10 minutes. Click here to go to my list of prompts.

“Create a vacuum day” (Inspired by this list of silly holidays.)


“Aren’t you the asshole that wiped out Charlottesville?” the woman said, spotting me from across the diner. She walked over.

“Well, technically no, it wasn’t me,” I rubbed my arm. I felt eyes study me from all around.

“Your work then. Whatever. I didn’t think I’d ever see you in person, or at least not without a fake beard.”

“I’m not ashamed of what happened,” I said. “Regretful, yeah, but not ashamed.”

“How do you work that out? Wiping out thousands of homes and businesses because you did something stupid?”

She looked genuinely curious. I was used to being berated. But maybe she would understand. I launched into the speech I’d recited in my head so many times. The speech no one ever let me speak. “Have you ever seen a vacuum chamber setup? A real, scientific one? For trying to create nothing, the suckers are enormous. And chock full of specialized equipment, like pumps that can literally be destroyed if they have to push thousands of atoms rather than tens. Frankly, I thought it was all a mess. I thought I could do better,”

She cocked her head to the side. She looked like she thought I was nuts, but she didn’t look angry.

“It was a wild idea,” I continued. “So wild I didn’t tell my advisor. But I didn’t need to tell him, I had the materials to get it done on the cheap.”

“Yea, yea, yea,” she waved her hand. “You decided to make a black hole in one instead, I watch the news. And trust me, no matter how you tell that part, it won’t sound clever to someone who lost a house to it.”

I looked away. “I can’t do anything about that now. I ran simulation after simulation that looked fine. I still don’t know what happened.”

“You got it wrong.”

“I really don’t think I did,” I said. “And I’m not afraid to be wrong—really, go find my undergraduate biology professor. I don’t have any data, it all got destroyed, but something other than just a black hole happened that day.”

She frowned. “You got it wrong. Apparently you are afraid to admit it. How sad that you can’t even see that.”

She walked away.

“Excuse me,” an elderly woman with a colorful scarf said from a booth nearby. “I can’t help but have overheard your conversation. And I have a theory about what went wrong that I’ve entertained for a while. Are you willing to try to reproduce your experiment?”


Fun Science: Vacuum and Pressure

Pressure is caused by collisions between particles. Scientists use the term “vacuum” when there are few particles, and thus few collisions. Air in our atmosphere is dense with particles; atmospheric pressure is very high compared to lab vacuum or the vacuum of space. Scientists use vacuum in many ways. Vacuums were used in lightbulbs and vacuum tubes (such as the old CRT or cathode ray tubes of old TVs and computers). Vacuums are used for depositing materials in clean environments, such as on silicon wafers for microcircuitry. Vacuums are used for separating liquids that have different evaporation points. In scientific labs, we can produce pressures billions of times lower than atmospheric pressure, but the pressure in space is still lower.

Atmospheric pressure: Every cubic centimeter (also called a milliliter) of air contains 2.5 x 1019  air molecules. That’s 25,000,000 trillion molecules, where the US debt is roughly $12 trillion, and a terabyte (TB) hard-drive holds a trillion bytes of information. That is a lot of particles causing a lot of collisions. The average particle travels only 66 nanometers before colliding with another particle. That’s only about 200 times the size of a nitrogen molecule.

On top of Mount Everest: Pressure is roughly 1/3 of the pressure at sea level, and there are 8 x 1018 molecules of air per cubic centimeter. The average particle travels 280 nm before colliding with another particle.

Incandescent light bulb: The pressure inside a lightbulb is 1 to 10 Pascals (pressure at sea level is 100,000 Pascals). There are still about 1014 molecules/cm3, or 100 trillion molecules. The average particle travels a mm to a cm before a collision. This pressure is too low for plants or animals to survive.

Ultra high lab vacuum: The most sophisticated lab vacuum equipment can produce pressures of 10-7 to 10-9 Pascals, yielding about 10,000,000 to 100,000 molecules/cm3, respectively. Particles travel an average distance of 100 to 10,000 km before colliding with another particle. Such extreme vacuums require highly specialized equipment, including specialized pumps and chambers. Only certain materials can be used; paint, many plastics and certain metals can release gases at very low pressures, making them unsuitable.

Space vacuum: The vacuum of space depends on what part of space you mean. The pressure on the moon is 10-9 Pa, or roughly our highest lab vacuum, with 400,000 particles/cm3. The pressure in interplanetary space (within the solar system) is lower yet, with only about 11 particles/cm3. It is estimated that there is only about 1 particle per meter cubed in the space between galaxies. Still, some microorganisms have survived exposures of days to space vacuum by forming a protective glass around themselves.

Going the other way, there are pressures much higher than the pressure of our atmosphere.

At the bottom of the Mariana trench: Pressure is about 1.1 x 108 Pa, or about 1100 atmospheres. A variety of life has been observed in the Mariana trench.

At the center of the sun: Pressure is about 2.5 x 1016 Pa, or 2.5 x 1011 atmospheres, or about 100,000 times the pressure at the core of the earth. This pressure is sufficient to fuel the fusion process of the sun, where hydrogen is combined to form helium.

At the center of a neutron star: Pressure is about 1034 Pa, or 1018 times the pressure at the center of the sun. Here, pressure is so high that normal atoms with electrons around a core of protons and neutrons cannot exists. Nuclei cannot exist in the core of a neutron star.

Read about other science topics on my fun science page.