Would discovering that the universe was actually infinite or finite change anything regarding our understanding of physics? |
- Would discovering that the universe was actually infinite or finite change anything regarding our understanding of physics?
- Why rocket engine "exhaust pipe" is shaped like a bell rather than a nozzle?
- If hand sanitizer kills 99.99% of germs, then won't the surviving 0.01% make hand sanitizer resistant strains?
- Does the universe rotate?
- Is there anything physically unique about the visual part of the EM spectrum?
- If the CMB was released when it was cool enough for recombination to happen, how are different parts of CMB hotter than others?
- If space and time are relative, then doesn't the age of universe change depending on where you are?
- When and how did we learn that space is a vacuum?
- If just the amount of protons determine what kind of element an atom is, could we transform an element's atom into another by changing this amount? What are the problems and challanges in this?
- Is there a limit to how many atoms there can be in a molecule?
- At the very edge of an event horizon do photons have a velocity of 0?
- Can the Born probability rule be derived from the Shrodinger's Equation, or is it an additional postulate?
- If an asteroid passed through the 36,000km satellite oribtal plane, would it sweep through destroying satellites or is it likely to just pass through and not touch anything? How densely filled is this satellite region?
- Which animals/things crossed the Bering Strait from North America to Asia millions of years ago?
- What are Bose Einstein condensates?
- What burns during re-entry?
- What about vitamin C helps your immune system?
- How do microwaves vibrate water molecules if microwave waves are so much larger?
- Why do all stars almost look the same size when they are so far away and apart?
- Would it be possible to use a neutrino stream to send communications through Earth?
- When an ohm-meter shows a negative value, how was it determined?
| Posted: 10 Oct 2017 05:26 PM PDT |
| Why rocket engine "exhaust pipe" is shaped like a bell rather than a nozzle? Posted: 11 Oct 2017 02:47 AM PDT If you have a nozzle shape, the gass exiting will result in higher exhaust velocity, giving higher impulse. Then why they use bell - like form? Edit: typo [link] [comments]  |
| Posted: 11 Oct 2017 07:00 AM PDT |
| Posted: 10 Oct 2017 04:15 PM PDT |
| Is there anything physically unique about the visual part of the EM spectrum? Posted: 11 Oct 2017 06:51 AM PDT My understanding of the electromagnetic spectrum is that everything from radio waves to gamma rays are just electromagnetic waves with different wavelengths. Is there anything that makes the visual spectrum unique beyond just happening to be what our eyes evolved to see? I understand that some animals have the ability to see some ultraviolet light or have infrared detectors, but for the most part we all seem to see the same very narrow part of the spectrum. Is there any reason we couldn't just as easily see only UV light or see entirely in the IR spectrum? Going further, is there a reason we don't see radio waves (the sun puts these out, right?) Is there something physically unique about that narrow band of the electromagnetic spectrum? [link] [comments]  |
| Posted: 11 Oct 2017 05:09 AM PDT So I heard that the reason CMB is not perfectly smooth, is because when recombination happened, some places of the universe were sligthly denser, and therefore hotter. Here is what I have trouble with understanding. The recombination supposedly happened when matter became cool enough for electrons to be "absorbed" by atomic nucleus. This should mean that no matter the density, recombination will always happen at a specific temperature. Therefore the released blackbody radiation (CMB) should always be of the same temperature. Therefore the CMB should be perfectly smooth. If some places of the universe were hotter than others, the CMB should have just been released at a different time depending on location, but the temperature should be the same. [link] [comments]  |
| If space and time are relative, then doesn't the age of universe change depending on where you are? Posted: 10 Oct 2017 07:20 PM PDT For example, time moves slower on the surface of a black hole, meaning black holes are actually younger in their time than our time. Doesn't this apply to the universe too? [link] [comments]  |
| When and how did we learn that space is a vacuum? Posted: 11 Oct 2017 01:16 AM PDT I'm guessing that before the era of spaceflight scientists already knew about this, and they knew how to construct spaceships so that poor Laika or Gagarin wouldn't die. But when did we go from all of the ether story to actually knowing it's vacuum? [link] [comments]  |
| Posted: 11 Oct 2017 07:09 AM PDT Can we add or remove protons to change an element atom into another? I guess neutrons and electrons will then be handy for stability. Isn't this what happens in fusion or fission? Can we smash Hydrogen and Helium together to make Lithium? I know some elements are artificially made, so why we don't play with this and turn Cobalt into Iron or Gold into Platinum or Iridium, ecc.? Stability it's tricky? [link] [comments]  |
| Is there a limit to how many atoms there can be in a molecule? Posted: 11 Oct 2017 07:18 AM PDT |
| At the very edge of an event horizon do photons have a velocity of 0? Posted: 11 Oct 2017 05:34 AM PDT At a location where if they were closer to singularity they would be pulled in and if they were any farther away they would escape. [link] [comments]  |
| Posted: 11 Oct 2017 07:14 AM PDT |
| Posted: 10 Oct 2017 02:59 PM PDT This article got me thinking. If it was passing a bit closer to Earth, would it be putting lots of satellites at risk? [link] [comments]  |
| Which animals/things crossed the Bering Strait from North America to Asia millions of years ago? Posted: 10 Oct 2017 04:19 PM PDT To clarify, It's known that humans crossed the Bering Strait from Asia to North America, but I never considered what animals came from NA to Asia. Any and all answers are appreciated :) [link] [comments]  |
| What are Bose Einstein condensates? Posted: 11 Oct 2017 06:52 AM PDT I vaguely heard something a bout this a while ago and asked my chem teacher, who said there was no 5th state of matter. Which cconfused me. What are they? [link] [comments]  |
| Posted: 10 Oct 2017 07:26 PM PDT I know that when something re-enters the atmosphere there is burning, but I want to know what is burning. In the case of a meteor, is the meteor burning or is the air around it burning and the heat is breaking apart the meteor, same question applies to shuttles and other space craft re-entry. If the air is burning then what in the air is burning? (Also is this a chemistry question?) [link] [comments]  |
| What about vitamin C helps your immune system? Posted: 10 Oct 2017 06:53 PM PDT There's vitamin supplements that are marketed to help you get better if you have a cold, but if your body is already fighting the bad stuff, how do we know if vitamin supplements are actually doing anything? [link] [comments]  |
| How do microwaves vibrate water molecules if microwave waves are so much larger? Posted: 11 Oct 2017 01:33 AM PDT Bonus question, just how small, into ionising radiation does a wavelength have to be to start damaging cells, and how does it do it? [link] [comments]  |
| Why do all stars almost look the same size when they are so far away and apart? Posted: 10 Oct 2017 01:58 PM PDT Follow up: Should not the suns ratio to the stars be diffrent? [link] [comments]  |
| Would it be possible to use a neutrino stream to send communications through Earth? Posted: 10 Oct 2017 05:37 PM PDT Would there be any advantage to it or are any form of neutrino detector to bulky or expensive? [link] [comments]  |
| When an ohm-meter shows a negative value, how was it determined? Posted: 11 Oct 2017 12:20 AM PDT I took some unexpected electrical measurements on the human body. I attached two metallic wrist straps to my arm, and clipped one lead of an ohm-meter to each strap. With dry wrist straps, I was expecting to get readings of around 1 MΩ. If I connected the meter one way, that's what I got. To my surprise, if I swapped the leads, the meter read around NEGATIVE 1 MΩ. Obviously, a negative resistance is impossible. I switched the multimeter to a volt-meter setting, and I was able to see around 50 mV across the two straps. The human body has bioelectric potentials, and I had managed to connect to two points that had different potentials. Obviously a simple attempt to measure resistance will be meaningless in this situation. I understand all that, but what I would like to understand is how the ohm-meter determined the negative value that it displayed. The classic Wheatstone bridge ohm-meter tries to zero the current flow across the bridge galvanometer, by adjusting a resistor. The lowest value that resistor can have is zero ohms, and if that still doesn't neutralize the current flow across the bridge... then what? I suspect that the multimeter isn't using a Wheatstone bridge after all, but what might be used in its place, I don't know. I also don't know whether that "negative resistance" value is expected to be meaningful. I did notice that it was roughly -1.0 times what I got when I swapped the leads. [link] [comments]  |
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