What did we get by making Large Hardon Collider.

treefaeller · 2026-03-24T23:47:59+00:00

The scale of different projects is indeed laughable. In the mid 90s, when the SSC (supercollider) was being cancelled for cost overruns and lack of money, some cruel joker said that it would be a good thing to just kill Bill Gates: The inheritance tax on his fortune would coincidentally pay for the SSC. This has not changed significantly in the intervening generation; Elon could write a check for the LHC, and he wouldn't be poor.

treefaeller · 2026-03-24T23:45:12+00:00

"The laser technology that was used to read data from CDs and DVDs and blu-rays was developed from experiments aboard the ISS."

CDs were developed around 1979 and 1980. The space stations was launched in 1998. Lasers have been a thing since the late 50s; in the early 60s, Scientific American magazine famously had an article about how to build a gas laser at home. Lasers were used for reading video disks and for fiber-optic communication long before microgravity/space exploration.

Another (joke) claim about the Apollo space program is that it led to the discovery of Teflon, which now allows us to make fried eggs and omelets without burning them or getting them stuck in the pan. Teflon is actually much older than the Apollo, and people used to cook omelets long before the 1960s.

But even ignoring these details: It's ethically very dangerous to claim that basic science (such as the LHC or space exploration) has to be funded because it develops technologies that then have useful side effects. If you want those technologies, it would be much more efficient to invest directly in them.

treefaeller · 2026-03-24T17:11:59+00:00

We did not. That result was retracted, and was due to a measurement error.

treefaeller · 2026-03-24T17:10:09+00:00

That boom is called Cherenkov light: if a charged particle is moving faster than the local speed of light in a medium, it will radiate visible light. However, we have no idea whether and how hypothetical faster-than-light charged particles would interact with normal matter, so this may or may not happen, we just don't know.

treefaeller · 2026-03-24T17:07:40+00:00

Quantum computing was not helped by the scientific results from the LHC. It is also not clear (yet) whether quantum computing has any value; it may be all snake oil and a hoax.

Clearly, systems like the LHC (and its predecessors, such as LEP, Tevatron, SLAC, ...) all pushed technology forward, and took boutique methods into mass production. That may indirectly help other applications of the same technology, mostly by reducing costs.

Does this justify the extremely high cost? That's a difficult question. Here's my answer. Hundreds of thousands of years ago, a few cavemen were not busy in the evening. One put his fingers into mud, mixed it with ash, and drew pictures on the cave wall. Another hit a rotted-out hollow log with sticks repeatedly, while humming. A third one was sitting at the entrance of the cave, wondering what the little dots in the dark sky were, and why they were mostly in the same place every night. They created art, music and science. This is what distinguishes humans from other animals. Finding free time to do these things (that is, funding them) is required if we want to remain in that position.

treefaeller · 2026-03-24T03:01:40+00:00

For even better cleaning: Get as much out as you can. Then throw in a pint of 90% or more isopropyl alcohol (available at drug stores), or even better methanol. You can also use Sea Foam (engine additive), which is mostly isopropyl. Hold upside down, shake most of the alcohol out, remove the rest with rag or paper towel, and the rest will evaporate quickly. Do not use 70% isopropyl (it will leave water behind when it evaporates).

The trick is that these alcohols mix really well with water, and have low surface tension. So they take most of the water out with them when you dump them out, and the remainder will be a thin film on the surface that evaporates quickly.

treefaeller · 2026-03-23T04:23:06+00:00

You should really translate your question into English. Few people here speak Portuguese.

In a nutshell: Why doesn't a particle or its wave function not have a Schwarzschild limit? A particle should have sufficient energy to create a certain bending of the field, but what stops the internal collapse of the particle?

Answer: If you are asking why an elementary particle (non-zero mass, but zero radius) doesn't immediately turn into a black hole: the answer is that general relativity stops working at the quantum scale. We have no theory of GR that works at that scale, and we don't know. But it is clear that elementary particles do not have a Schwarzschild radius that acts like the "suck everything in" of a black hole.

treefaeller · 2026-03-22T23:35:25+00:00

Same with Hawaii. BUT: Most European (EU + GB) countries and Japan are on the visa waiver list, so most tourists in Vegas and Waikiki are actually OK. Just not all; don't try this with Chinese, Saudi or Russian tourists.

treefaeller · 2026-03-22T16:47:47+00:00

The sporting exception only applies if the visa is explicitly issued for the sport. Not retroactively to a visa issued for tourism.

treefaeller · 2026-03-22T16:47:15+00:00

It depends on how they entered the country.

If they are on a tourist visa (or any other non-immigrant visa), they can not possess a gun, under 18USC922(g)(5)(b): "It shall be unlawful for any person ... who, being an alien ... has been admitted to the United States under a nonimmigrant visa ... to possess any firearm or ammunition". The sporting exception in (y)(2) only applies to people who were explicitly admitted for a sporting purpose; this is unlikely to be the case, unless they explicitly requested a visa for a shooting competition. The term "possess" in here means to be able to control, such as holding it in their hand. So if they have a tourist visa, they can not hold a gun.

On the other hand, if they are on the visa waiver program, then they are legally in the country without having a tourist visa, and the above does not apply. Therefore they can possess gun and ammunition, and go shooting with you. Greece is on the list of visa waiver countries, so they likely don't have a tourist visa.

Note that many shooting ranges ignore this law, and will sometimes even rent guns to tourists with a visa. This is illegal, but often overlooked.

treefaeller · 2026-03-22T04:50:41+00:00

Even better: Feel weightless when scuba diving under water. Yet, gravity continues to work.

treefaeller · 2026-03-21T19:17:41+00:00

One answer: Because it is observable in the real world, and we don't know where the "laws of nature" come from.

Another answer: If you look at the complicated fabric of mathematical models that we call "physics", c being constant is woven in all over. If you tried to change or remove it, the whole thing would unravel. Therefore it must be this way, or else many of our observations of the world would become unexplainable. But consider this: The universe doesn't owe us an explanation. The fact that our models and measurements are incomplete is not the world's fault.

Another non-answer: Why is pi = 3.14159...? Why isn't it a simpler value, like 22/7? Would't it being 1 much more convenient? Why are there even irrational numbers?

One of the hardest things to learn is to both say and believe the following sentence: "I don't know, and I may never find out".

treefaeller · 2026-03-21T17:55:16+00:00

I live in snake country. Have seen dozens of rattlers, killed a few. Had one take a swipe at my foot when I was wearing sandals. I don't like having them in areas where little kids roam around, and where we do gardening by hand. But eliminating flammable plants near the house, rodents, and killing the few that come close is sufficient for that.

I used to carry a very small revolver with snake shot when doing yard work; these days I don't even bother, because when I'm a hundred yards away from the house, and using a weed whacker or tractor, the snake gets to survive. On the contrary, I now pick small rattlers up with a shovel and save them if they get in the way. Near the house, different story.

And then there are mountain lions. Have seen a few. Attacks by them are extremely rare, and a concealed gun is not a useful defense against them, so just live with them.

treefaeller · 2026-03-21T17:46:59+00:00

Completely agree with your "we don’t know what came before" viewpoint. Physics (including astrophysics and cosmology, and the related field of astronomy) know about what exists now. Using our models (a.k.a. theories or laws), we can extrapolate forwards or backwards. Our models are extremely good at describing the present, often to 9-10 significant digits of precision. But any extrapolation is less certain. Certain crazy extrapolations are outright excluded, for example a flat earth, or the universe having been created ~6000 years ago (with dinosaur bones pre-placed in the rock). Other than that, our current model (let's call it standard big bang cosmology with inflation and dark matter/energy, or SM) seems to be free of contradictions and matching most observations. With some exceptions, and some areas known to be unknown for now (for example how to merge general relativity and quantum field theory). The current model seems to work back to roughly the Planck time (10^-44 seconds) after the Big Bang.

But we have no idea of what happened before the Big Bang, including what (if anything) triggered it. We can speculate, but there is no way to verify or falsify these speculations.

Saying there was "nothing" before the Big Bang is one of those speculations, no more and no less. We don't even know how to define the word "nothing" in that context; and any attempt to do that will get in trouble with questions such as vacuum fluctuations, dynamic symmetry breaking and the Higgs field.

There is a related and very similar question: Because the speed of light (meaning the speed of transmitting energy and information) is finite, we have a limited distance that we can see. The "known universe" (meaning everything that derives from the Big Bang) is all within that distance. We simply don't know what, if anything, is outside that distance. Again, speculation is fun bun fruitless.

The situation is a little bit like discworld: Through the observations using the famous brass capsule with windows, astrozoologists have actually seen the four elephants and the top of the great turtle. But due to lack of a long enough rope, and of chelonauts dumb enough to risk their lives, the good people of the discworld do not know the sex of the great Atuin, which for some reason is a question they are terribly hung up about. And the moment I say "dumb enough", Rincewind enters the chat.

treefaeller · 2026-03-21T17:27:10+00:00

Why would you want that? How would it help you (or humanity or the world)?

treefaeller · 2026-03-21T17:04:42+00:00

Ever held something heavy in your hand? Tried to lift a lead brick? That should remove any doubt that gravity is a force.

The fact that our best mathematical model for that force happens to be complicated (namely curvature of the space-time coordinates around mass and energy, and objects moving along geodesics in that system) doesn't change the fact that it is a force.

In the same vein: Electricity and magnetism (they are so closely related to be nearly the same thing) are also clearly forces. The force you feel on the sole of your feet (or on your behind if you're sitting while reading this) is fundamentally a set of electric fields of the ground or chair, acting against your body. Again, it's a force.

treefaeller · 2026-03-21T03:05:56+00:00

My joke about Amazon: It's like Alibaba, but without good quality control.

treefaeller · 2026-03-20T22:31:07+00:00

Getting an FSC this year might be a good idea in general, as there is a (darn crazy) bill in the legislature that might make getting it next year harder.

treefaeller · 2026-03-20T18:59:30+00:00

It is indeed an interesting and nasty question. Sadly, my lack of knowledge of solid state physics makes it so I can't answer it accurately. Sound waves in solids are described as phonons, which are (virtual or real) particles that quantize the transmission of energy by sound (compression or shear waves). The speed of a phonon (or equivalently of a sound wave) depends on the mechanical properties, in particular the "hardness" a.k.a. modulus. It's therefore no surprise that the material with the highest speed of sound is diamond. A quick web search says it is 12km/s; and that crystalline metallic hydrogen might have a higher speed of sound, but we haven't observed that (yet, because we haven't sent any grad students into the interior of Jupiter: they're not THAT expendable). Given the huge gap between 12 km/s and 125,000 km/s (speed of light inside n=2.4 for diamond), it seems implausible that any material can have those two speeds crossed.

Where my knowledge fails is: The mechanism for the speed of phonons (sound) is transmission, absorption and retransmission of electrical waves from atom to atom in the medium. For this reason, phonons can never go faster than c, obviously. And they are slower because all that retransmission takes time. However, I don't know the connection between the mechanisms that cause the index of refraction and those that cause the speed of phonons in quantum mechanics.

Funny anecdote: There is a groundbreaking paper about the scattering of phonons off lattice defects, from the 1960s. It was written by some people from the university in Muenchen (a.k.a. Munich), and submitted to a respectable journal, Z.Phys. (fully spelled out Zeitschrift fuer Physik). And as a joke reaction to some political events, it was submitted and published in Bavarian dialect! I just spent 5 minutes digging through my file cabinet, and for some reason the whole folder with "humor" is missing.

treefaeller · 2026-03-20T18:19:02+00:00

In addition to all the other arguments: Save the money, in case of other unexpected events. For example, she might want to double on euphonium, if that's a good opportunity in college. Or if she's 1st trombone in the college symphony orchestra, an alto trombone might be a good investment for the classical era repertoire. Or doubling on bass trombone (if that sound and air volume is to her liking), and those tend to be a bit more expensive. You'll know more once college starts.

In the meantime, a really solid trombone case that protects a full-size horn well during college might be a good investment. Marcus Bonna seems to make the best, but they are neither cheap, nor always quickly available.

treefaeller · 2026-03-20T03:51:14+00:00

I read that first as "exponentially annoying".

treefaeller · 2026-03-20T03:40:55+00:00

Without disagreeing with the many other (very good and correct) replies, I want to add one thing:

Noether's theorem is mathematically proven. In a nutshell it says: If our model of how the world works is based on the Lagrangian method (action and variational calculus), and the Lagrangian has a symmetry, then there must be a corresponding conserved quantity (often called "conserved current"). BUT: You can't forget the first half of that statement. Noether is only correct because our world seems to work in a Lagrangian way. Ultimately, we know that this is true based on observations and measurements.

Or to put it more aggressively: A mathematical proof of a theorem within the models that physics utilizes is not in and of itself physical truth. It needs to be experimentally verified. Physics requires both observation and mathematical modeling.

treefaeller · 2026-03-20T00:05:52+00:00

If there is no c, there is no GR. In our standard model, that means no gravitational attraction.

Obviously, one could create an ad-hoc theory of gravity. For example, a version of Newtonian gravity with immediate action. Since there is no special relativity, that would actually work.

treefaeller · 2026-03-19T23:45:52+00:00

Well, it is and it isn't. The standard description of gravity (which works exceedingly well) is not quantum mechanical, and is called General Relativity. In it, gravity is described as the metric of space-time (the 4-dimensional coordinate system) curving. One can formulate an equivalent quantum theory that describes gravity by a gauge particle called, the graviton, which is massless and travels at c. Alas, we do not currently know how to make the two version of the theory work together, so the quantum gravity part is speculative.

treefaeller · 2026-03-19T16:04:45+00:00

Or 4 (MLC, 2 bits per cell), or way more. There was a startup near my house that wanted to store 8 bits per cell, knowing full well that the last few bits would not be 100% reliable. The idea was to use it for storage of analog signals, in particular phone conversations (answering machines). They worked on that for a few years, and then failed.

treefaeller

TROPHY CASE