What is a birth mark and why do so many people have them? |
- What is a birth mark and why do so many people have them?
- How can superconductors and superfluids be completely perfect?
- Why don't we have an exact number on the maximum mass of neutron stars?
- How does the hardware for quantum computers differ from classical computers?
- Is there such thing as a "perfect whitebody"/reverse blackbody? i.e. something that absorbs and emits no thermal radiation at all
- Is it possible for other planets with two stars to have star eclipses? Would the star get extra bright or would the star blocking the other star dim the light?
- Why all satellites and space station orbit west to east and not north to south?
- Can photons collide? What happens when we point two torches one at another?
- When electrons give off energy to return to their ground state energy levels in the form of light (incandescence), where do the photons come from?
- Why limit password length?
- Why do trees shed their leaves and go dormant during fall?
- how can our ears tell us exactly the direction sound is coming from?
- Are there any ways in which a lunar space station would be cheaper or have advantages over the ISS for science and research purposes?
- How are studies on rat behaviour applicable on humans?
- Do small "Cold Plasma" generators produce any harmful particles/ions/ozone?
- Do we know how optical illusions affect animals? Can we learn about their sight that way?
- In using directions in interstellar space, how are locations of objects tracked?
- Could Mars dust storms potentially contaminate category 5 areas off limits to the Category 4-B rated rovers?
| What is a birth mark and why do so many people have them? Posted: 25 Sep 2017 08:33 PM PDT |
| How can superconductors and superfluids be completely perfect? Posted: 26 Sep 2017 03:58 AM PDT So often in maths and physics we have to approximate the real world. Wires aren't perfect, they have some resistance; fluids have some viscosity but we assume zero friction... except when they don't. Superconductors actually exist, and they have:
and certain isotopes of helium, when supercooled, flow without loss of kinetic energy. How on earth is this possible? I'd understand negligible friction, or loss of energy, but precisely zero? [link] [comments]  |
| Why don't we have an exact number on the maximum mass of neutron stars? Posted: 25 Sep 2017 07:17 PM PDT A trail of reading wiki lead me to the page on the Tolman–Oppenheimer–Volkoff limit. It says the maximum is approximately 1.5-3.0 solar masses, which seems like a big window to me. One of the sources mentions composition and charge...but I thought neutron stars were uncharged and just made of, well, neutrons? I imagine if the neutron star was spinning fast, centrifugal force would allow it to remain stable with a little more mass. Other than that, my instinct would be that calculating a maximum mass shouldn't be as complicated as it is. [link] [comments]  |
| How does the hardware for quantum computers differ from classical computers? Posted: 25 Sep 2017 06:26 PM PDT Are they still largely silicon based or has the focus been on different materials? [link] [comments]  |
| Posted: 25 Sep 2017 11:52 PM PDT |
| Posted: 25 Sep 2017 03:12 PM PDT |
| Why all satellites and space station orbit west to east and not north to south? Posted: 26 Sep 2017 04:21 AM PDT |
| Can photons collide? What happens when we point two torches one at another? Posted: 25 Sep 2017 12:39 PM PDT |
| Posted: 25 Sep 2017 04:08 PM PDT It's my understanding that the reason things visibly glow when heated is that the electrons have been excited to a higher energy level, and in order to return to their ground state energy level, they give off radiation, some of which is within the visible spectrum, causing the glow. Anyway, when electrons "give off" photons like this as visible light, where do the photons come from? [link] [comments]  |
| Posted: 26 Sep 2017 12:00 AM PDT Heaps of banks do this. I don't see how it can provide any benefits. [link] [comments]  |
| Why do trees shed their leaves and go dormant during fall? Posted: 25 Sep 2017 04:25 PM PDT In high school biology classes I've learned that photosynthesis is the process during which trees utilize CO2 and water to produce carbohydrates and oxygen, and the mechanism requires sunshine and chlorophyll. There's some birch trees growing outside my house and for the past few years I've been observing that the onset of leaf shedding varies. Some years it's earlier in the season, late August-ish while other years it's later in the season, late September-ish. I associate this with temperature, because some years I need warmer clothes earlier in the season and some years later. However, according to the photosynthesis formula only water, co2 and sunshine are required so why don't trees keep photosynthesizing and grow during winter? Where in the plant would this temperature sensitivity be if not involved in the photosynthetic process? [link] [comments]  |
| how can our ears tell us exactly the direction sound is coming from? Posted: 25 Sep 2017 03:11 PM PDT |
| Posted: 25 Sep 2017 11:23 PM PDT |
| How are studies on rat behaviour applicable on humans? Posted: 25 Sep 2017 11:44 AM PDT Rats brainsize is only a fraction of ours and I assume function very differently [link] [comments]  |
| Do small "Cold Plasma" generators produce any harmful particles/ions/ozone? Posted: 25 Sep 2017 10:38 AM PDT I've come across such articles that state that small Plasma generators in certain Air Purifiers or AC units are very harmful to health. However, most manufacturers nowadays have mid to high end devices that incorporate some sort of "PLASMA FILTERING" that uses "NEGATIVE IONS" to battle smoke, bacteria and dust or whatnot. I have settled on an AC that has a small (~4 inches wide) cold plasma generator box shaped device in the inside mounted unit. So my question is can these small devices potentially be a health hazard in the home? Does a cold plasma generator produce Ozone or Ions that can "survive" long enough to travel outside the unit and fill up the whole room and pose a health risk to people inhaling them? Does inhaling such negative ions and ozone particles cause health problems in the first place? And are these not particles that are supposed to exist in nature and aren't we already exposed to them? [link] [comments]  |
| Do we know how optical illusions affect animals? Can we learn about their sight that way? Posted: 25 Sep 2017 11:13 AM PDT |
| In using directions in interstellar space, how are locations of objects tracked? Posted: 25 Sep 2017 08:25 AM PDT First, I figure there is some type of coordinate/grid system, so I am wondering about that and what we use as the x,y,z: (0,0,0) point of center for that system if we track objects in a three dimensional plane. Second, how do we tell relative direction? For example, we use north, south, east and west on a theoretical plane (like on Earth) to tell direction, but in space, there is not only x and y axis, but z as well. Are there directions for this? Or would we just use up and down as the 3rd dimensional directions? [link] [comments]  |
| Posted: 25 Sep 2017 05:42 PM PDT I was thinking about this earlier today, and an earlier post on here prompted me to post. Basically, there are classifications for the cleanliness of spacecraft doing research looking for life on planetary bodies. What I'm wondering is, although while the rovers (which are not rated clean enough to do research in potential water areas) are far away from water areas, could the global dust storms on mars potentially pick up microbes from the rovers, and transport them to the parts of mars that might have water? Is this a problem that we have worried about? [link] [comments]  |
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