3257: Beam Pipe

2026-06-18T10:48:51Z

2A02:586:4D08:4300:7404:A3E6:60F5:8BEF: /* Explanation */ Last paragraph, first sentence: Clarified what sort of increase in water pressure is called "impossible" (otherwise one can increase the pressure as described in the second paragraph).

{{comic
| number = 3257
| date = June 10, 2026
| title = Beam Pipe
| image = beam_pipe_2x.png
| imagesize = 309x397px
| noexpand = true
| titletext = 'If you keep trying to spray your collaborators with the beam when they're not looking, I'm turning off the ion source and NO one will get to play with the beam!' --Physics's mom
}}

==Explanation==
{{incomplete|This page was given a Nobel prize for its effort. Don't remove this notice too soon.}}
When a liquid is flowing within a tube, the pressure at any point is determined by an equilibrium between the supply pressure and the forces that restrict flow, such as friction with the walls and hydrodynamic effects in the liquid. If the tube is short and the outflow opening is large, the pressure within the tube is close to the exterior pressure (air pressure, in the case of a liquid flowing into air). If the outflow opening is negligible, the pressure within the tube is essentially equal to the pressure of the liquid's supply. If the tube is constructed of an elastic material, it will expand until an equilibrium is reached between the internal pressure and the elastic stretch of the tube... unless the pressure is enough to rupture the tube.

In the case of a hose carrying water, if the exit is fully open, the water pressure near the exit will be moderate: greater than atmospheric pressure, but less than the full pressure of the water supply. The more the exit is restricted, such as by part covering it with a thumb, decreasing the water flow, the closer the pressure near the exit will come to the full pressure of the water supply. (In the limiting case where the exit is fully blocked, the hose will essentially be an extension of the plumbing, and its internal pressure will be that of the water supply, as modified by the gravitational effects of raising or lowering the hose, and the weight of the water). If the hose is elastic (e.g. the usual garden-hose reinforced rubber), it's possible to see it stretch as the nozzle is restricted. Covering it with a thumb, while reducing the water flow, allows the water that does come out to do so at relatively high pressure.

As the {{w|Large Hadron Collider}} ("LHC") can be considered a sort of "pipe" (a beam pipe, as pointed out in the comic title), this comic makes the ridiculous assumption that the same logic applies there — that its beam can be concentrated and redirected by partially covering the end of the beam with a thumb. This wouldn't work in real life: water molecules are moving at low speed and thus do not have sufficient energy to overcome the electrostatic repulsion between their electrons and those of the thumb, forcing them to change path. In contrast the kinetic energy of the particles in the LHC (7 TeV, in the case of protons destined for 14-TeV proton-proton collisions) is far far larger than the repulsion of the thumb. Most particles will pass through unaffected, while those hitting thumb nuclei directly will produce a cascade of new particles similar to those the LHC is intended to produce. This procedure would have to be done at one of the LHC's two [https://home.cern/autopsy-lhc-beam-dump/ beam dump sections], where the contents of the beam are allowed to exit into long steel-encased graphite blocks. Over time, those blocks become dangerously radioactive from the impact of the beam particles. There isn't currently any means to bypass these blocks and allow a person to interact with the beam while the LHC is in operation. Although the section of the 'pipe' shown seems to indicate that it is in a section where one or other of the {{w|Compact Muon Solenoid|main detectors}} surrounds the pipe (which, during inoperable periods of construction, modification or other extensive maintenance, might have a part of the adjacent length of pipe withdrawn), this couldn't be done while the system was running. Apart from the basic problem that the system can't work while part of it has been removed, the interior of the LHC must be maintained at an extremely high vacuum while it's running.

While there is no recorded case of a human getting struck by the particle beam at LHC, {{w|Anatoli Bugorski|Anatoli Petrovich Bugorski}} did accidentally hold his head into the proton beam of a 76 GeV (about 180 times less than the energies at the LHC) particle accelerator while trying to repair a faulty part. This had severe but not lethal consequences: the resulting acute radiation sickness caused the affected parts of his face to swell and the skin to flake off, The affected nerves never recovered, leaving the left side of his face paralysed and his left ear deaf. The damage to his brain resulted in several epileptic seizures, but did not affect him otherwise, allowing him to continue his work as a physicist, and at time of publication he was still alive at the age of 82.

Thus, while pointless, holding the thumb into the LHC beam for a short time is unlikely to significantly harm anyone trying it... apart from possibly requiring amputation of the thumb, if there was enough tissue damage or induced radioactivity. At any rate, this wouldn't work in real life: the relativistic particles would not behave as a liquid.

The title text expands the joke, once more treating the LHC as if it were a hosepipe. Applying the effect above to a hosepipe is a common thing for children to do — often to spray family and friends with the pressurized water. This applies the same logic to the LHC, imagining the mother of "physics" (the science, as opposed to a person) telling off their presumably adult child for "spraying their colleagues with the beam" — something very incomprehensible in real life.

A variety of devices are marketed to increase the pressure of water supplied to them past what would result from decreasing the outlet area. The {{w|pressure washing|pressure washer}} is a common example; it uses electrical power to add force to the output water. There are also scams based on devices that supposedly attain this increase ''without'' using any externally-provided power, but this is a physical impossibility. The force of the water coming out can't be greater than the force of the water coming in, or a perpetual-motion device could be constructed with the water running in a loop and the added force being tapped to power a generator. At most, the output pressure will be the same as that of the water supply, in the limiting case of zero flow, less any frictional losses within the device.

==Transcript==
{{incomplete transcript|Don't remove this notice too soon.}}

:[A picture shows a (partly obscured by the panel) particle accelerator (namely this one being the Large Hadron Collider at CERN). Megan is shown on a stepladder, covering the beam pipe with her thumb. Cueball is shown standing behind the ladder, watching.]
:[Caption below the panel:]
:This year's physics Nobel will go to the scientists who figured out that you could make the Large Hadron Collider more powerful by covering part of the beam pipe with your thumb.

{{comic discussion}}<noinclude>
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Physics]]

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3257: Beam Pipe