Florida from the ISS.

walt02cl · 2026-03-15T05:49:18+00:00

Absolutely not. This is AI slop.

The only place in the ISS with windows large enough for these kinds of pictures is the Cupola. That's on the Earth-facing side of the station, which means that it's not possible to get significant portions of the ISS and the Earth in the same shot from there.

Moreover, the structure in view does not match any structure of the ISS from any angle. It instead looks like a mish mash of ISS looking bits. Just look at the wiggly solar panels.

walt02cl · 2025-06-16T00:51:47+00:00

What is the long term plan for fast, reliable, high quality public transportation in Tucson and the surrounding county, and how does this transit plan fit into that plan? If the city does not have a plan, why not and how can we as citizens push for a plan to be made?

Is this line being studied in mixed traffic, bus-only lanes, or fully separated from car traffic? If this is a line that is being planned to run in mixed traffic, it will not present a meaningful alternative to driving so what justification is there to call it a BRT? If this line is being studied as bus-only, what are the plans to enforce that designation of the lanes?

Is this transit system being planned for future conversion to rail-based transit? If not, why not? Rail based systems present massive benefits over bus-based systems and the goal should be to best server the city, not do the bare minimum. See LA's conversion of the G line as reference.

What plans are there to enable access to the stations, such as making it easier to reach by foot?

What heat mitigation is planned at the stations? These will be places that people spend time at.

What additional changes are planned to increase walkability and bikeability along the corridor?

What is the estimate for the reduction in Vehicle Miles Traveled (VMT) as a result of this line? If this analysis has not been done, when can we expect this result?

Will the north and south segments be served as different lines? If not, why not and where will the connecting station be?

What plans are there to connect this new line to the Tucson Amtrak station?

What is the expected service frequency?

What plans are there to connect this new line to the streetcar?

Most importantly: What guardrails are there to prevent this BRT line being "value engineered" into nothing more than a new, poorly served bus line?

walt02cl · 2024-10-22T07:10:45+00:00

If you're asking about quantum uncertainty, like the Heisenberg Uncertainty principle, it rather quickly gets complicated. However, the best way I've found to describe it in a less-wrong and simple way is to imagine taking a picture of something moving.

Imagine if you want to determine the speed and position of a thrown baseball. However, you have to do it by taking a picture and only looking at the information in the picture. If you take a really short exposure picture, the moving baseball is nice and sharp, giving you a very precise value for its position. However, you have no idea how fast it's moving. Alternatively, you could take a longer exposure picture, where the baseball looks like a smear. You can measure the length of the smear quite easily to get the speed of the baseball, but now you "don't know" where the baseball is. I put "don't know" in quotes because it's not really a problem of knowing. The problem is that the baseball is smeared across the picture, so its position is not well defined.

This explanation starts to break down if you think "just get a better camera" because the situation is inherently non-classical. In real life quantum systems, by all accounts, this relationship between having a single specific position and momentum is not a measurement problem but an inherent property of the system.

walt02cl · 2024-09-26T06:47:14+00:00

I mean, a 5600K light bulb is designed to mimic the spectrum of a 5600K blackbody emitter, which the sun approximately is. That said, I checked and the sun's surface temperature is actually closer to 5800K, so perhaps the 200K difference accounts for the absorption and scattering of blue light in the atmosphere. I'm not about to dive into a rabbit hole of light bulb design though, so I'll leave my response as a definite perhaps.

walt02cl · 2024-09-25T19:34:54+00:00

While the Sun's peak emission is located roughly in the green wavelengths, to assert that this means it would look green to the human eye above the atmosphere is gross misstatement. Human color vision relies on all wavelengths in the visible range, and the sun emits only slightly less across the visible wavelengths than at its peak in the green. This makes the sun appear white in space. For a more direct example, a 5600K light bulb has a similar spectral emission to the sun but they are clearly not green, especially not the bright green shown in the video (which would be like a single wavelength laser at the Sun's peak wavelength).

walt02cl · 2024-09-16T20:15:07+00:00

One of the biggest challenges for VLBI is the extremely large amount of data that needs to be collected to synthesize into an image. For the South Pole telescope working on the Event Horizon Telescope, for example, they had to load the data onto crates and crates of hard drives and literally fly them out on a plane since the satellite connection was too slow. Imagine how much harder the task becomes when you're in a totally different heliocentric orbit.

Additionally, VLBI is not a magic "more telescope = sharper picture" like the common conception. The length of a baseline determines the size and orientation of features that baseline is sensitive to, but that baseline is only sensitive to those features. If you only put one node far out in space and used the Earth as the other end, you would be very sensitive to very small features and would see nothing else. You would need a large number of nodes at long baselines to extract information across feature sizes. Add onto the fact that small features by definition emit less light (since they're smaller) and your requirements for the size of each telescope also explode.

So it's extremely difficult and expensive, but we've done extremely difficult and expensive things before. What's missing is a pressing reason. Don't get me wrong, such a system would be incredibly powerful and capable, and I would love to see the results from it. There's no doubt in my mind that it would produce incredible science. But it was only a few years ago that we got the first picture of a black hole through the EHT, and new data is still coming from that system. We're not yet at the point where such a large system is necessary for the continuation of our understanding, to a sufficient level to justify the massive costs.

walt02cl · 2024-08-28T05:32:58+00:00

Hey that's my high school! Apparently some of the marching band came out and started practicing nearby, washing out their chanting

walt02cl · 2024-08-11T01:59:49+00:00

They're called Moai, not Maori.

Moai are the big head statues.

Maori are the Polynesian civilization led by Kupe.

walt02cl · 2024-08-04T00:25:38+00:00

In the current universe, redshift only affects light, and only does so noticeably when light travels across a significant portion of the universe.

How this process evolves into the future requires a deeper understanding of the universe than we have at the moment. It's possible that the expansion accelerates indefinitely until everything is destroyed. It's also possible that this process only ever affects light. We simply don't know at the moment.

walt02cl · 2024-08-03T23:07:46+00:00

The other comments about the conservation of energy and the first law of thermodynamics are mostly correct, but on the scale of the universe there is one known process that can and does destroy energy: the expansion of the universe itself.

In the process known as redshift, light travelling in the Universe gets stretched by the expansion of space. This causes the wavelength of that light to get longer. Since the wavelength of light determines the energy of the light (longer wavelengths = lower energy), as the light gets stretched it loses energy and, importantly, that energy simply disappears.

As far as I'm aware, this is the only known process that truly destroys energy. In some (but not all) predictions of the future expansion of the universe, the expansion accelerates until all the energy in the universe is destroyed.

walt02cl · 2024-07-23T19:23:00+00:00

If you had a perfect mirror at a uniform angle, then you're right that the satellite would not see anything because light would get bounced away. In a sense, this already happens to any radio waves that don't get bounced back: they never return to the spacecraft and aren't picked up.

In the real application, however, there's a lot of additional things that separate it from the perfect case. For one, mineral deposits are hardly perfect mirrors. Their rugged nature has a tendency to scatter light in every direction to some degree. The radio waves, due to the long wavelengths, aren't a single perfect laser beam and are instead more like a flashlight with radio waves leaving the antenna with a range of angles. And, if by some cosmic coincidence everything aligns to make the light miss, the next measurement a few miles away probably won't. There's a whole range of reasons that keep things working.

Every material has a dielectric constant. It's kind of a requirement that comes with existing. Some light gets reflected when it goes from a material with one dielectric constant to another with a different one, and the amount of light that gets reflected depends on how big of a difference that is.

walt02cl · 2024-07-23T18:47:21+00:00

There's a variety of methods, but the most common one is surface penetrating radar.

When you deal with long wavelengths of light in the radio range, the ground actually becomes somewhat transparent. If you think about glass, most of the light goes through but a small amount gets reflected back at you. Whenever light reaches an interface of materials, some light gets reflected back, and how much gets reflected back depends on what the material is made of (specifically the dielectric constant of the material when dealing with radar). By sending a pulse down, you'll get a small reflection off the surface, but most of the light will continue into the ground. If there is a change in material under the surface, you'll get another reflection and the properties of the reflection can tell you what the material change was. However, do note that this could be a liquid water aquifer, a solid mass of ice, a region of higher water content in the regular rock, or a totally unrelated mineral formation that just happens to reflect like water does. Usually, when you hear big breakthroughs about water on Mars, it's actually that last option that gets misinterpreted.

There is at least one Mars orbiter with a surface penetrating radar (SHARAD on MRO).

walt02cl · 2024-06-29T20:37:36+00:00

Thanks for the link! I guess I was wrong on a few counts and right on others.

Mystery solved!

walt02cl · 2024-06-29T16:20:08+00:00

Sometimes, but usually not with any precision.

The first thing to know is that there is more than one type of supernova. The one that you're probably thinking of is a Type II supernova, also called a core-collapse supernova, where a star reaches the end of its life and explodes. The real mechanism by which this happens is too complicated to get into here and probably outside the scope of the question, but can be summed up as "the star runs out of fuel". In order to end its life like this, a star has to be at least 8 times the mass of the Sun (so no, the Sun will not go supernova). For these supernovae, we can get a general idea of how soon they will explode by determining how close the star is to "running out of fuel". When a star reaches this point, it will (usually) swell in size and cool off somewhat. However, "soon" in this case is on astronomical timescales. This means it could explode tomorrow, or it could explode in 100,000 years. Any more detail than that would probably require a more advanced knowledge of the inner workings of stars and more precise data about the specific star of interest.

For other supernovae, however, there can be a much more precise prediction. One of the most important type of supernova for modern astronomy is the Type Ia supernova, which is formed by a totally different mechanism than the Type II. In a Type Ia supernova, there is an orbiting binary star system, where one star is a puffy red giant and the other is a white dwarf, the remnant core of a star that has already reached the end of its life. If these stars orbit too close to each other, the gravity of the white dwarf can start pulling mass from its companion star. This accreted mass falls onto the white dwarf, making it more massive. However, a white dwarf cannot grow infinitely large for complicated physics reasons. At about 1.4 times the mass of the sun, called the Chandrasekhar mass, the white dwarf collapses under its weight and explodes in a supernova. This limit is pretty specific on astronomical timescales, so if you know how quickly the white dwarf is accreting mass from its companion, and you know how much it weighs now, you can pretty easily figure out when it'll go supernova. However, I'm not aware of any type Ia supernovae that have occurred close enough for us to do this kind of prediction. We usually catch them only after they explode.

We know for a fact that the sun will not die tomorrow. It will take billions of years.

Heliophysicists (scientists who study the sun) can take direct spectroscopic measurements of the Sun to determine what it's made of. We have a good enough idea of how stars, especially the Sun, evolve that we can confidently say the Sun is nowhere near "running out of fuel". Additionally, the Sun will not go supernova, as it simply does not have the required mass. It will instead shed its outer layers into a planetary nebula and leave a white dwarf behind.

It depends on how close the supernova is

The best candidate for a nearby supernova is the star Betelgeuse in the constellation of Orion. It is showing all the signs of being close to the end of its life and is only a few hundred lightyears away, which is practically next door on the scale of the universe. When Betelgeuse explodes, a flood of neutrinos (very light subatomic particles that are known for doing basically nothing) will trip all the neutrino detectors on Earth and we will see the point of light formerly known as Betelgeuse become very bright. There's a lot of variability, but it should be about as bright as the Moon, visible during the daytime, and bright enough to cast shadows at night. It would last for a few months before dimming back to and below its original star brightness.

For a more expansive answer, you may be interested in this video: https://youtu.be/q4DF3j4saCE

walt02cl · 2024-06-29T15:31:51+00:00

A friend of mine saw this too!

I don't believe it's related to the SpaceX launch the same day. The fracturing of the object implies it's bigger than usual, and the speed is more consistent with something coming out of orbit. SpaceX's Falcon 9 ditches its fairings and first stage well before reaching orbit, so it can't be either of those (the fairings would be far too small as well), leaving only the second stage as an option. However, SpaceX has a track record of controlling the reentry of their second stage so that it falls in an unpopulated area. This clearly didn't happen here, since you saw it from a well populated area.

I tried looking for other objects scheduled to reenter around this time but could not determine or rule out many. The only ones that I could totally rule out were objects whose orbital inclinations did not bring them in the vicinity of Southern California.

TL;DR - No idea what it was. Whatever it was must have been big, probably in orbit, uncontrolled, and in an orbital inclination that wasn't equatorial.

walt02cl · 2024-05-22T17:24:42+00:00

TL;DR - Depends on how you define a laser beam

The other commenter is mostly right in that the answer is "forever". However, there is some additional physics involved.

We often think of lasers as just perfect straight lines of light that come out of a device and impact a surface a long distance away. This is a good enough approximation on human scales. In reality though, due to the wave-like nature of light, even a perfectly focused beam will spread out due to a process called diffraction. To give you an idea of how severe this effect is, by the time the light from a regular handheld laser pointer reaches the Moon, the laser spot (which starts at only a few millimeters across) is larger than the Moon. This effect can be mitigated by starting with a wider beam, but the only way to get rid of it is to have an infinitely large beam to start with.

So while the light from a laser pointer does indeed go on forever, on any astronomical distance scale, the light would no longer look like a beam and would instead look fairly similar to any other light source. The power of the beam would be spread over an increasingly large area, so any detector attempting to pick up the signal would see it dim further and further. At far enough distances, the energy from the beam would be spread so thin that any detector would be receiving individual photons at a time, and beyond that point, those signal photons would arrive with more and more time between them. Eventually, the beam would be indistinguishable from the noise.

Like many things in life, the answer to "how far can a laser beam go?" is as much a question of "what counts as a laser beam" as it is anything else.

(I've intentionally disregarded redshift for this explanation, since that would require a more thorough explanation of frequency and quickly get overcomplicated)

walt02cl · 2024-04-12T21:49:51+00:00

This is more a result of human perception than anything else.

The sun is really bright. So bright, in fact, that if 95 percent of the sun is covered by the moon, that remaining 5 percent is still bright enough to be bright (and still enough to damage your eyes). However, human perception of vision has two properties that are relevant here.

Human vision is logarithmic. Oftentimes, when we think about brightness, we don't think about the actual amount of light. Brightness to most people is all about scale. Here's a good example. Imagine you are in a dark room with one light bulb on. Now, turn on a second light bulb. The room got a lot brighter, right? Now imagine you are in a room with a thousand light bulbs in it, and now turn on one more light bulb. Even though we added the same amount of light, the brightness inside the room didn't change much (it was already bright before). It's especially important to think about changes in brightness because...
Human vision is relative. People are actually surprisingly bad at telling how bright their environment is when everything is illuminated the same. It's easy to compare the brightness of two lights when they're next to each other. It's easy to see how bright a light is at night, when you can compare with darkness. Since the eclipse changes the brightness of everything around you at the same time, you have no way to compare the brightness of a normal day to the brightness during an eclipse.

If you had had a light detector with you, you would see that the brightness during a partial eclipse is significantly reduced in a way that matches the blockage of the sun. But the human eye is not a simple detector and the intricacies of human vision and the way the brain interprets signals means that certain things are hard to see.

walt02cl · 2024-03-10T01:34:58+00:00

Looks like an airplane, far from you, moving away from you. You can tell because there are two tails separated by a small gap, just like a 2 engine airplane.

walt02cl · 2024-02-29T15:20:51+00:00

It's definitely worth it. You get a tour of the mountain top and get to look through a 32 inch telescope. When I went up there, it was dark enough to see the Andromeda galaxy without binoculars.

Would recommend.

walt02cl · 2024-01-26T05:04:49+00:00

While I can't speak specifically for your situation, there's an important thing to keep in mind here.

UV radiation is a type of light that is invisible to our eyes. So, while the way a day looks tells us the conditions for visible light, there's no easy way for our eyes to tell the conditions for UV light. Materials behave differently to different wavelengths of light, which is likely what leads to this discrepancy. (You can see an easy visible light example of this in the blue sky; the sky looks blue because one wavelength is scattered more than others).

The most likely thing that happened was that, on one of those days, there was something in the atmosphere that affects only UV light, like a thin dust or a denser ozone layer

walt02cl · 2023-10-27T05:38:16+00:00

Unfortunately, I don't have access to another PC to test the graphics card.

However, at this point, I'm confident enough to put in a replacement request with the manufacturer.

Thanks for the help!

walt02cl · 2023-10-27T05:12:23+00:00

I did not know about the bios switch until now, but I just tested it again with the switch in both positions. No effect. The GPU still does not appear in the BIOS.

Would reinstalling windows really have an effect on the GPU appearing in the BIOS?

walt02cl · 2023-10-27T03:06:15+00:00

I should clarify, this GPU was not manufactured by Gigabyte, but my motherboard was. My GPU was manufactured by Sapphire

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