With the element radium being so rare, only a few kilograms total being mined over time, how did it make it into so many different consumer products, from watch dials to health elixirs? |
- With the element radium being so rare, only a few kilograms total being mined over time, how did it make it into so many different consumer products, from watch dials to health elixirs?
- How does light affect our mood?
- Does detonating two nuclear bombs side by side have the same effect as detonating one doubly-large bomb?
- If quantum entanglement can't be used to transmit information, then how is this experiment (see description for link) possible?
- Can someone please explain the science behind a snowball hitting a wall?
- How are scattering cross-sections measured?
- Maximum information density of photons?
- Why does the intensity of all electromagnetic waves dissipate at the same rate, 1/r^2?
- Why Dimensional Analysis / Buckingham Pi Theorem Works?
- If space is expanding outwards, would part of the night sky eventually get darker?
- How do devices like cell phones and laptops determine the signal strength of wifi signals?
- How does the Hubble telescope position itself to observe different parts of the sky?
- What is the speed of kinetic energy?
- What is the most probable physical distance between you and a random person on the internet?
- Is there a scientific approach to creating (and maintaining) a landfill other than covering trash with giant mounds of dirt?
- [Physics] What is the difference between the sounds of different vowels?
- Why is CMB in every direction?
- For a project like Breakthrough Starshot, how is it possible to take an image that is useful when it is moving 15-20% of C?
- How do your sinuses drain in outer space?
- Why does my water bottle sometimes expel gas when I open it? Is this due to the chemicals in the water?
| Posted: 09 Sep 2017 12:20 AM PDT |
| How does light affect our mood? Posted: 08 Sep 2017 08:58 PM PDT |
| Posted: 08 Sep 2017 06:37 PM PDT |
| Posted: 08 Sep 2017 04:41 PM PDT Been catching up on some reading, came across this experiment here. I've been told over and over again that entanglement can't be used to transmit information. So how the heck does this work? Aren't they extracting or inferring information about one photon's path from its entangled twin's behavior -- the exact sort of thing I've been told isn't possible? [link] [comments]  |
| Can someone please explain the science behind a snowball hitting a wall? Posted: 09 Sep 2017 05:24 AM PDT I watched a video a while ago explaining how when a snowball reaches a certain speed it will explode on impact no matter what angle you throw it at. That's why you end up with a perfect circle of snow left on a wall when the snowball hits it. But this is true for any substance I think. If you get something to a specific speed it will explode on impact. The video I watched related this to the rods from god project. I was trying to explain this to a friend and I couldn't remember the phenomenon or the science behind why this happens and I couldn't find the video I watched so if someone can help me out by explaining this that would be great. [link] [comments]  |
| How are scattering cross-sections measured? Posted: 08 Sep 2017 08:19 PM PDT The question itself is: I have seen on certain textbooks/study material that in order to measure the amount of particles scattered by an angle a, one must place a detector in such an angle with respect to the direction of the incident particles and pointing towards the target and simply count events. However, I can't see how it does not happen that the particles reaching the detector come from various impact parameters. To try and make it a little clear: If you put a detector far away and with a big scattering angle and count the amount of particles reaching it, you will get some counts belonging to particles with big impact parameter which were not scattered at all. On the other side, if you place the detector with no angle at all, you won't measure the amount of particles which were not deflected, because those (usually, I guess) have a big impact parameter. Maybe I have a wrong understanding of what a scattering cross section is. From what I understand, in the case of a rigid potential such as a hard sphere, it is the area of interaction of the potential projected onto the plane of incidence. With continuous potentials, this generalizes to a measure of how strong/how much the incident beam is deflected by the target. [link] [comments]  |
| Maximum information density of photons? Posted: 08 Sep 2017 07:59 PM PDT It impossible to transmit information faster than the speed of light (instantly), but is there a limit to the amount of information that can be transferred at the speed of light. [link] [comments]  |
| Why does the intensity of all electromagnetic waves dissipate at the same rate, 1/r^2? Posted: 08 Sep 2017 02:00 PM PDT I tried to find some answers about this fascinating property online, but all I got was the math behind it. Anyone have a more simple explanation as to why all electromagnetic waves behave this way? Thanks. [link] [comments]  |
| Why Dimensional Analysis / Buckingham Pi Theorem Works? Posted: 08 Sep 2017 04:58 PM PDT I know that we can use dimensional analysis to experimentally correlate several variables and to reduce the amount of experiment that you need to do to determine those correlation. I also know that it can be used to scale things up. In the example above, we want to study how drag (F) is effected by fluid velocity (v), viscosity (mu), density (rho) and diameter (D). Using dimensional analysis / Buckingham Pi Theorem, we can reduce the variables into Drag Coefficient and Reynold numbers. But why is this valid? Why does Buckingham Pi Theorem led to a conclusion that increasing fluid velocity and increasing fluid density will have the same effect on the drag coefficient because both conditions led to the same Reynolds Number? Buckingham Pi Theorem did not take into account any fundamental principles. Every readings I encountered only explained why dimensional analysis is necessary and how to do it. I never found any resources that tried to explain why Buckingham Pi Theorem is justified. [link] [comments]  |
| If space is expanding outwards, would part of the night sky eventually get darker? Posted: 08 Sep 2017 11:43 PM PDT Mainly referring to stars that are getting farther away but also other factors if relevant. If everything is moving away from a point, would that point eventually be darker/emptier than the rest of the sky? [link] [comments]  |
| How do devices like cell phones and laptops determine the signal strength of wifi signals? Posted: 08 Sep 2017 10:52 AM PDT |
| How does the Hubble telescope position itself to observe different parts of the sky? Posted: 08 Sep 2017 02:14 PM PDT |
| What is the speed of kinetic energy? Posted: 08 Sep 2017 03:23 PM PDT This might be an odd question but is there a speed of kinetic and potential energy? I ask this because I'm sitting on a couch right now and there is a water bottle about a foot away from me. My movements and even my heartbeat is making the water in the bottle move. If I get up, the water is still. So I know it's me and not, say, air current from my fan or AC. Now, I've been trying to figure out how fast it takes my heartbeat to transfer into the water. Is there a set limit or is it based on the force, in this example my heart, acting on the water? Or is it like sound or light where it only moves in one single speed? [link] [comments]  |
| What is the most probable physical distance between you and a random person on the internet? Posted: 08 Sep 2017 01:03 PM PDT |
| Posted: 08 Sep 2017 06:23 PM PDT If so - what kind of things are taken into consideration? [link] [comments]  |
| [Physics] What is the difference between the sounds of different vowels? Posted: 08 Sep 2017 08:22 AM PDT I'm not asking about how they're made or the physiology in any way. I mean, if you recorded two sustained vowel sounds, chopped off the beginnings and the ends, and compared the sustained sounds in the middle, what differentiates them? What differentiates a Long A from a Short A or an E? Is it pitch? Timbre? [link] [comments]  |
| Why is CMB in every direction? Posted: 08 Sep 2017 01:47 PM PDT The cosmic microwave background radiation (CMB) is observable in every direction. It is the radiation emitted by the opaque plasma that existed after the big bang that is now reaching us 13 billion years later. if we are still moving away from the origin of the big bang, surely after 13 billion years we would have exited the bounds of the plasma cloud that sources the CMB. Is this true? If so, why is the CMB in every direction? Wouldn't it be like looking at the earth from above the surface, filling a little or a lot less than half the sky? [link] [comments]  |
| Posted: 08 Sep 2017 02:11 PM PDT Wouldn't any camera able to capture images at that speed be too large to be considered for starshot? [link] [comments]  |
| How do your sinuses drain in outer space? Posted: 08 Sep 2017 07:06 AM PDT |
| Posted: 08 Sep 2017 07:57 PM PDT |
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