# KG3

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Spacecraft Engineer

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1. ## Confused about black holes

Try looking at it like this. You build a ship and you put enough fuel in it to go twice the speed of light (2c). I'm back on earth watching you go. You've told me that you are going to burn 100 gallons of fuel a minute for 30 days to get up to 2c. Everything is going great as far as I can tell until I notice that it's taking you longer to burn up that 100 gallons of fuel. There appears to have been a change plan on your part. That same 100 gallons of fuel is taking longer than a minute to burn. It looks like you're slowly taking your foot off of the accelerator and stretching that 30 day burn out to 60 then 90 days. Not only that it appears that the exhaust gasses leaving your engines are going at a slower and slower rate making them less efficient the faster you go. Even if you do mange to burn up all that fuel it still won't get you up to the speed of light never mind twice! The only remedy for this is of course send the next guy with MORE BOOSTERS!!! Of course for you on the ship everything goes as planned and you get to Alpha Centauri in only 2 years.
2. ## Special Relativity Questions

I'm not a physicist either but I have put some thought into this. Anyone else can feel free to jump in and help me out! The speed of light is constant for everyone evolved and there lies the tricky bit. Say you wanted to go to Alpha Centauri 4 light years away but you only wanted to spend 2 years traveling there. All technical aspects aside you can do this. You calculate how much fuel you need to accelerate to 2c, light the fuse and away you go! Newtonian physics works for you the same way it always seems to work. You burn up the fuel, accelerate to 2c, Alpha Centauri in only 2 years... for you. Now if you've decided to drag race a photon from earth to Alpha Centauri you will be disappointed. You back up a bit so you've already accelerated to 2c when you pass the earth on your way to AC. So there you are traveling past the earth at twice the speed of light! Your ship is working perfectly at 2c, even the headlights and tail lights are working normally (despite what you might see out the windshield or rear view mirrors). You blow right past the earth at 2c when the photon you are racing leaves the earth at the poky speed of only 299,792,458 meters per second. You are traveling twice the speed of that photon but somehow it still passes you literally like you are standing still (at the speed of light). Still according to your clock it takes only 2 years to get to Alpha Centauri but to folks back on earth it's taken the photon 4 years and even more than 4 years for you to get there. That photon is going to beat you EVERY time and pass you at the speed of light no matter how much rocket fuel you burn up or how fast you are going, 2c, 20c, 20,000c. You can not change your relationship to the speed of light but what can do is change your relationship to time and space.
3. ## How ask a doctor for sick leave?

Where I live in the USA you are not likely to see your primary care physician before you get better from the cold or flu. I can literally take weeks before you get to see your doctor. If you are REALLY sick you can go to the emergency room. Many people here in the food service industry need to work every hour that they can and don't get paid sick leave. Also the boss might decide the employee is unreliable if they don't show up for work because they are sick and give them fewer hours to work or fire them entirely. This leads a lot of people to show up for work sick and is a real problem.
4. ## Hayabusa 2 arrives at ryugu, minerva II-1 "rover" deployed

How are rocks from Ryugu classified geologically? I'm assuming that the reason they are so interesting is that they haven't changed much over the eons but that also means that they are not on the familiar rock cycle of igneous, sedimentary, metamorphic that we find here on earth.
5. ## Mysterious cloud on Mars.

Are there any working seismometers on Mars?
6. ## For Questions That Don't Merit Their Own Thread

Yes, I believe these are standard issue in the army of cloned Marilyn Monroe. https://www.youtube.com/watch?v=hEyWqVfY4vo
7. ## For Questions That Don't Merit Their Own Thread

I guess I will post this here. In the movie First Man, the scene where Neil Armstrong was flying the X-15 they showed the altimeter on the aircrafts instrument panel. It displayed an altitude on over 100,000 feet it I recall correctly. If an altimeter works by measuring barometric pressure at what altitude does it stop working? Same with pitot tubes. Is there an altitude that pitot tubes stop reading air speed because there just isn't enough air?
8. ## For Questions That Don't Merit Their Own Thread

Gamma rays are high energy photons, I don't think they will be influenced by a magnetic field. Are you maybe thinking of cosmic rays? The solar wind is made up of charged particles, protons, electrons and alpha particles and makes up most of the radiation in the Van Allen belts.
9. ## What do you think about "First Man" a naw biopic movie about Neil Armstrong?

I didn't like the movie much. It seemed like it was filmed entirely with a shaky hand held camera. Also the director tries to get you to connect emotionally with Neil, his wife and other characters by using extreme close up shots of their faces. Long lingering close up shots of faces, with a jittery hand held camera. I felt like I spent 2/3 of the movie staring into the nostrils and inscrutable forlorn eyes of Ryan Gosling. I think that the director would have put the camera directly into his sinus cavity if he could! It did really nothing to help the story and just made me mad after a while. But that's what I get for sitting in the second row of the theater.
10. ## Serious Scientific Answers to Absurd Hypothetical questions

I will try to tackle question #3. The stuff we can observe in the observable universe is either stars or has something to do with stars. We can see galaxies going back to just millions of years after the big bang and they are lit by stars. Everything about stars from how they are formed out of clouds of gas to the fusion that powers them to how they organize themselves into galaxies requires mass and gravity to work the way it does. If it didn't we would see galaxies that just didn't look right or there would be stars that exploded as they were forming or some such thing. As far as the unobservable universe, well you got me there. If we can't see it maybe there aren't any working stars there?
11. ## what is geo orbit

Should be pointed out that geostationary earth orbit is different from geosynchronous earth orbit. I was confused by this at one time but I assume that I'm still confused so please someone correct me. A geostationary satellite orbits prograde over the equator (or close to) every 24 hours and appears to stay (mostly) in one spot in the sky. A geosynchronous satellite orbits every 24 hours but can be more inclined. I believe a geosynchronous satellite can in a polar orbit or an elliptical orbit (such as a tundra orbit) and maybe even retrograde orbit too maybe?.
12. ## Bad science in fiction Hall of Shame

Close to being spot on about the horse. Although in my area there are some folks that still use horses and even oxen on small farms or logging in ecologically sensitive areas. Also there are plenty of people who aren't rich or live in the country/suburbs but still own horses: https://www.youtube.com/watch?v=NGgdxN532zE I think that it's a bit sad that horses have been shod for over 2000 years but the invention of machine made horseshoe nails happened just 20 years before the invention of the automobile!
13. ## Bad science in fiction Hall of Shame

Ok, this is a pet peeve of mine. A parsec = the apparent parallax movement of one arc second of an astronomical object compared to more distant objects due to earths motion around the sun. So a parsec probably is not a standard unit in an interstellar society. Unless it's like a foot, which was a particular persons foot at one point but most people have switched to metric... I liked the movie Men In Black. At one point in one of the movies aliens give earth 3 standard galactic months to return their (whatever it was, can't remember) or else they would blow up the earth. Then they say 3 standard galactic months = about 20 minutes!
14. ## Bad science in fiction Hall of Shame

If the plane was configured for take off or landing and all of it's systems failed it would probably stall and come down rather quickly. The longest glide of a commercial airliner was about 120 km by an Airbus A330-300. They lost power to both engines as they were cruising at 39,000 ft because of a fuel leak. These planes have a small wind turbine that can deploy to give limited power to some of the planes electrical systems and hydraulics, so they did have some control over the plane. The scariest part I think was that the cabin slowly decompressed because the air compressors stopped working! https://www.youtube.com/watch?v=ie55MjoVHLw
15. ## Serious Scientific Answers to Absurd Hypothetical questions

Does the intended use of the device get taken into consideration? After all, if you put a pint of petrol in a bottle with rag stuffed into it you have a bomb. If instead you put the same petrol in the fuel tank of your car you have fuel.