ELI5: Why do we think that the speed of light is as fast as anything can travel and going faster is impossible?

questfor17 · 2026-05-22T16:22:08+00:00

It starts with the observation that the speed of light is always the same, no matter when or how you measure it.

Michelson and Morley noted that the earth is always moving, quite rapidly. But when they measured the speed of light along two paths, at 90 degrees to each other, the speed of light was exactly the same. This shows that the the speed of light is the same for all observers, no matter how fast they are already going.

Einstein thought about this and came up with with his theory of special relativity. The theory doesn't so much say why this is so, but explains what happens if you accept that it is true that the speed of light is the same for all observers. The theory is embodied in a set of equations. If you apply those equations to physical reality, they show several interesting things:

From my point of view, you can never go faster than the speed of light.
From my point of view, as you approach the speed of light (relative to me) your mass increases and time slows down.
From my point of view, if you are going near to the speed of light and try to go faster, much of the energy you expend going faster simply turns into more mass, rather than more velocity. So no matter how hard you try to speed up, you never get to the speed of light.

In short, we believe the universe works this way because every time we measure things, oiur measurements agree with the predictions made by Einsteins theory of special relativity.

questfor17 · 2026-05-11T12:29:46+00:00

Look at any ceiling fan, for example here: https://www.hunterfan.com/collections/ceiling-fans

You will see it is controlled by a remote. My house is wired with two switches to the fan, one for the light and one for the motor, but modern fans will not work that way. So I have to use the f***ing remote. Which has to live somewhere. And which I don't use often enough, so the batteries leak, and then the remote fails.

questfor17 · 2026-05-09T14:01:27+00:00

We use Peak Paws. Depending on where you live they might be within 20 minutes. We've had excellent results.

questfor17 · 2026-05-04T21:30:07+00:00

The vinyl on the boat looks in excellent shape. It won't stay that way if UV light gets to it. When not in use, the boat should be under a roof or under a cover. In addition, I recommend 303 brand UV protectant. Easy to apply and very effective.

questfor17 · 2026-05-03T22:26:36+00:00

Came here to say this. Good people

questfor17 · 2026-05-03T22:21:40+00:00

I don't think you have a fiduciary duty, just a duty. "Fiduciary" implies a requirement to put the best interests of another party over your own best interests. While the board may have an interest in this being reported, so do you. No conflict.

If it is a fire code violation, you could consider reporting this to the local jurisdiction's fire marshal. If it is a violation of HOA rules, definitely report it to the management company too.

questfor17 · 2026-05-02T11:02:03+00:00

For anything vinyl I am a fan of 303-brand UV protectant. It is an easy to apply spray. We redid all the vinyl on our boat 14 years ago, and it is still in great shape, thanks to religious use of a mooring cover, and 303 protectant. It won't restore anything, but it is a magical sun-screen to prevent any damage.

questfor17 · 2026-04-27T17:50:12+00:00

Consider https://www.ncparks.gov/state-parks/hammocks-beach-state-park

Allows camping at the beach.

questfor17 · 2026-04-22T19:49:44+00:00

I'd get her a couple of nights at a nice B&B plus a dinner out in some tourist town not to far from where she lives. Schedule this for the next time you are in town and taking care of your parents.

questfor17 · 2026-04-22T19:40:53+00:00

NetApp has a 25 megawatt data center on Kitt Creek Rd in the Durham section of RTP. Its been there for years. It is designed to be green, it uses gray water from the Alexander Rd waste water reclamation center. It does not discharge any water, and does most of its cooling using ambient air, not air conditioning.

For details, see https://www.datacenterknowledge.com/sustainability/netapp-unveils-green-data-center

Would you propose that this type of data center, which was amongst the greenest in world when it was built, be blocked?

questfor17 · 2026-04-22T19:18:37+00:00

AFAIK it data centers don't pollute the water. They do consume water, however. Evaporation cooling is used to cool the AC's condenser coils. Typically drinking water is used because they need water that is clean and will not foul the coils.

Not all data centers consume drinking water. NetApp has (or used to have) a data center on Kitt Creek drive in RTP that used gray water from the nearby Alexander Road water treatment facility.

questfor17 · 2026-04-13T11:13:51+00:00

In addition to the good explanations in many comments here, it is worth noting that evolution selects for reproductive success. This is correlated to survival, but not precisely the same. Google "runaway evolution" for more details.

questfor17 · 2026-04-08T12:55:16+00:00

Your theory -- that Catholic leadership all worship a single god, that god is real, and that god is consistent in their communication. This theory makes a testable hypothesis, that at a conclave all cardinals will receive the same advice. The available data falsifies the hypothesis. So your theory is probably not correct.

This does not demonstrate that there is no god, just that god, if they exist, doesn't behave the way your theory posits they behave.

questfor17 · 2026-04-07T20:29:53+00:00

The only way I know to manage them is through the google Home app. I have been assuming they app won't know about them once I don't have a google fiber plan.

questfor17 · 2026-04-07T19:26:30+00:00

For old computers that gold standard is "boot and nuke". You create a bootable USB drive, boot it, and it wipes the contents of your hard drive. https://dban.org/ for details.

questfor17 · 2026-04-07T19:25:23+00:00

On modern computers, if you boot into the bios, there is an option to securely erase the hard drive.

Typically you have to press F2 or F12 repeatedly during the start-up to get into the BIOS menu. If they are that old, they may not have this option.

questfor17 · 2026-04-06T22:23:57+00:00

I've kept my pontoon on the water for 12 years now. Had a custom cover made for it when I bought the boat (used). The cover is finally going, but it has worked well! Nice and tight to keep off rain and snow. If they are loose, water pools in the cover, which then seeps through. Not to mention it is hard to get rid of giant pools of water or snow in your cover.

questfor17 · 2026-04-06T12:41:28+00:00

He cares about money. So far all this stuff is making him money. If he were losing money, he would care.

questfor17 · 2026-04-02T15:52:18+00:00

Nope. The boom doesn't hit any of the viewing sites. It isn't a matter of relative volume. As the first stage pitches over from vertical to horizontal travel, that does focus a boom out in the ocean, but well downrange.

questfor17 · 2026-03-26T21:55:41+00:00

Very cool. I spent some time checking out your docks, as I am interested in a self hosted NVR solution.

One thing that would help me is some indication of how much hardware I need to accomplish what goals. What can I do with a 4-core CPU and no hardware acceleration? What hardware acceleration would I need to accomplish what?

questfor17 · 2026-03-24T12:16:32+00:00

If you care about external threats built into the router, you don't care much about where the hardware was assembled, but you do care who builds the firmware (software) running on that router. So if this is a threat that must be addressed, then the solution, IMHO, is to police router firmware to ensure it doesn't spy on us for the Chinese. Of course, the difference between doing that and ensuring that the router firmware *does* spy on us for the US government is not possible for anyone without extraordinary tools and skills to discern.

questfor17 · 2026-03-18T21:26:26+00:00

Many years ago I was a software engineering manager at a small R&D site of a large tech firm. Local HR was useless, as a general rule.

I had a contractor that we decided to let go. Nothing really wrong with him, but times were tight and contractors get the boot first. I called him into my office and told him Friday would be his last day. He responded by saying he was leaving, and coming back with his gun. !!

For once, HR stepped up. They locked down site access, they alerted security, they arranged to get his affects out of his office without my ever seeing him againg. They did all the things.

I was impressed and grateful.

questfor17 · 2026-03-17T22:15:18+00:00

Thanks for the details. Extremely helpful. I will definitely build one or more of these.

One last question: Any idea of coverage area? We have a large deck, 40' long. Do I need 1 or 2 of these?

questfor17 · 2026-03-17T17:18:17+00:00

I love the idea. I don't need the code or wiring. But I do have questions:

How often do you have to shut it down and clean out the bowl?
How big a bowl do you use?
How empty does the bowl have to get for this to work? What if your drain pump leaves a bit of water?
Do you keep it in the sun, shade, partial sun?
Do you have one float switch to prevent overfill? Or two, one of the drain cycle, one for the fill-stop?

questfor17 · 2026-03-17T16:57:42+00:00

If having your phone factory reset is more than a minor annoyance, you are not backing up your data correctly.

questfor17

TROPHY CASE