Jump to content

qqwertzde

Members
  • Content Count

    1,015
  • Donations

    $60.00 
  • Joined

  • Last visited

Community Reputation

330 Excellent

About qqwertzde

  • Rank
    Member - 1,000+

Profile Information

  • Gender
    Male
  • Location
    Nova Scotia, Canada

Flight Sim Profile

  • Commercial Member
    No
  • Online Flight Organization Membership
    VATSIM
  • Virtual Airlines
    No

Recent Profile Visitors

The recent visitors block is disabled and is not being shown to other users.

  1. I just had a look at the publication in the European Physical Journal (https://epjc.epj.org/articles/epjc/abs/2021/07/10052_2021_Article_9484/10052_2021_Article_9484.html ). This is a typical case of media blowing things out of proportion. They didn't perform an experiment, just numerical simulations of a different system, and those simulations led them to the Alcubierre metric (that's the mathematical model for a warp drive in relativity). I will not hold my breath that they can actually create a warp drive with this, not even a tiny one. Peter
  2. Newton's second law is 350 years old and is still valid. It explains most of the physics of flight, for instance. However, it is not considered a universally valid law anymore. It has its range of validity (very roughly anything larger than a micrometer to anything smaller than a galaxy), but it fails to describe larger structures or the realm of atoms and molecules. We have other laws for that, and those laws will for sure also have a limited range of validity. Time will tell. The infinite mass and zero length is just a limiting case. In order to achieve that, you would have to put an infinite amount of energy into the body. Even the entire energy in the universe wouldn't suffice 🙂
  3. Oh, you've found on one of my favourite physics experiments 🙂I remember well when that experiment was conducted in 1999, it was a big breakthrough, beautiful work. By now, scientists can even stop light in an atomic gas and retrieve it again ( https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.107.053603 ). But to your question: a more precise statement about the speed of light is that "nothing can go faster than the (local) speed of light in vacuum". The speed of light when it travels through nothing is called c=299,793km/s and is fixed. c poses an absolute speed barrier for everything (almost, see below). Virtually all of modern physics would have to be rewritten if something would go faster. However, nothing prevents light from moving slower when it is inside a medium. An intuitive picture is that light gets absorbed by an atom, spends a little time in it (as a form of energy) and is then re-emitted. As a consequence, its velocity is slowed down compared to a vacuum. This is basically what the people in the paper above have done. There is a beautiful effect in nuclear reactors that is a consequence of this: https://en.wikipedia.org/wiki/Cherenkov_radiation . In the cooling water of a reactor, light only travels at about 2/3 c. The reactor can produce electrons that move faster than that (but still less than c). These electrons produce a blue glow in the water. That's the short answer to your question. There are some ramifications that are worth mentioning: physicists distinguish between group velocity (the speed at which a short flash of light travels) and phase velocity (the speed at which light wiggles inside that flash) of light. The latter can actually be larger than the speed of light in vacuum, but since you can't use it to transfer information, there is no contradiction with relativity. It gets even more weird: in a curved space-time, space itself can travel, and the speed of space itself is not bound. For instance, the Hubble law states that galaxies move away from us faster if they are farther away from us. The galaxies are carried along with space, and, as seen from us, space far away could move faster than the speed of light in vacuum. Hence, light emitted from some far away sources can actually appear to move at superluminal speed, even though locally (roughly, where it has been emitted), it always travels at c. We just perceive it as faster. Peter
  4. Your second pic is even Blue in Green 🙂
  5. Just in case someone else will face the same problem: I found an old thread in the official MSFS forum in which it was recommended to update Windows. After I installed the latest Windows patches, MSFS is loading nicely again.
  6. Anyone else has problems starting MSFS today? It was slow all day to launch for me, typically taking 5 minutes or so. Tonight, it doesn't load at all. I managed to get a pop-up window that says they are synching data and should be done soon, but I've waited for 20 minutes and it doesn't go anywhere. Peter
  7. This is my favourite movie on black holes:
  8. I just had a look at the video. I didn't like his explanations with the angles very much. It is not really wrong, but I am pretty sure many people might get wrong ideas from it. Math is really important to properly understand all of this pretty confusing stuff, but it is not the reason why we think that light travels at the same speed for all observers. The reason is simply because countless experiments have shown that this is actually the case. Math just models these findings very accurately. My favourite relativity experiment is the GPS system. The satellites move at several km/s, which is a tiny fraction of the speed of light, but still enough to make their clocks go slower by several nanoseconds every day. Likewise, they are farther away from Earth, so gravity changes their time by a similar amount of time. Only if you take both effects into account will GPS give you your correct location on Earth. If relativity is ignored, your location will be off by a kilometer within a matter of days.
  9. Pizza! Definitely! ( https://insidetheperimeter.ca/physics-eating-pizza/ ) 😉 Conventionally, one would think of only one spacetime in which all matter and radiation is moving. However, in quantum physics, there is the many-worlds interpretation, which basically states that (many!) new universes are created each time we observe something. In that sense, everything is attached to many different universes. I am not a fan of that interpretation, but it is a consistent point of view. As for the muon, one can explain the conundrum of having different times for the person and the muon by taking into account that not only time depends on how fast something is moving ("time dilation"), but also space ("Lorentz-Fitzgerald contraction"). From the point of view of the person, the muon lives longer, so it can travel farther. From the point of the muon, it only lives for a microsecond, but since the Earth's surface is moving towards it, the distance is contracted. Hence, the muon does not live longer, but it has to travel a shorter distance to hit the Earth. The bottom line is: time and distance are relative in the sense that different observers will measure different values for both. However, the measurements will lead to the same physical conclusions (e.g., that the muon can hit the Earth). Yes, it's complicated 🙂
  10. Oh, you're opening a big can of worms there 🙂 Yes, time is relative. From the perspective of the muon itself (its own watch, so-to-speak), it will decay in a microsecond. However, if it is moving very fast from the perspective of a person, the muon may live much longer as measured on the person's watch. The muons we detect on Earth are generated in the upper atmosphere ( > 10km) and are moving close to the speed of light. Within a microsecond, they would only be able to cover a few hundred meters, but in our time they live sufficiently long to reach the Earth's surface. Gravity does not play a big role for these muons. Yes, clocks go slower closer to a massive object, but it is a small effect, only a few nanoseconds every day for satellites. However, for high-precision systems like the GPS network, you need to take that into account, otherwise GPS location would become unreliable within a few days. Peter
  11. Don't worry too much about that, Noel. It's my job to know that 😉 Peter
  12. Not quite. The electron is stable, it does not decay at all. The link you provided compares the decay time of muons (less than a microsecond) to the decay of atomic nuclei. The latter ranges from a much shorter time than the muon decay time so millions of years. A better comparison would be the decay time of other elementary particles. Compared to those, the muon actually lives quite long (since it can only decay through the electroweak force, as opposed to the strong nuclear force). Many particles only live about a billionths of the lifetime of the muon 🙂
  13. Yes, it's basically the same as an electron, just heavier. The main difference is that muons can decay into an electron (plus two other particles, but let's not get into details): since it has more mass M, it has more energy E = M c^2. A free muon therefore can release some of the energy to turn into an electron, but the opposite cannot happen for a free electron (it doesn't have enough energy). Luckily for us, since our world wouldn't exist if electrons were unstable. Peter
  14. The first thing I would do is to change the graphics settings to very low values. Your system should be fine with ultra settings, but for the sake of testing I would start low. If that helps, check out the process manager (ctrl + alt + del) and see if any other processes are running in the background. MSFS is incredibly well optimized and should easily get you 50fps.
  15. Indeed, I do. In our area, not even the observed weather matches what we actually experience because there are mountains between us and the weather station. If we have rain coming our of low-hanging clouds, the weather radar still shows clear skies 😄 There is no question that METARs aren't the perfect source for weather information. I currently fly a lot in Northern Manitoba, where many METAR stations are automated. They give you correct temperature and air pressure, but they do not observe the conditions (cloud coverage, precipitation). Until SU6, I usually had the choice between Asobo's omnipresent thunderstorm, or always flying with clear skies using REX's METAR-based weather 🙂 I think Asobo is on the right path, but they still need to put more work into the weather engine. They need to enable us to do flight planning with real-world weather information, which usually consists of METARs and/or something like Foreflight or Skyvector (in the US). I am quite optimistic that this will eventually be the case. Peter
×
×
  • Create New...