Karthikeyan KC

Forum Replies Created

Viewing 15 replies - 1 through 15 (of 91 total)
  •   Intuitive explanation for time dilation#9592

    I am oversimplifying this for the sake of explanation. According to relativity, any two observers in the universe who are in inertial frames must always agree about the speed of light. Always! Because it is proven to be constant in all conditions!

    If you and your friend have two light clocks (A light clock measures time-based on the ticks of a light beam that’s bounced between two mirrors A and B) each and are on the ground, the time measured with those two clocks will be in sync. Of course! Because you both are in the same inertial frame and the time it takes for the light to bounced off the mirrors in your clocks will be the same.

    But now let’s put you and your clock on a spaceship that can travel at half the speed of light. The spaceship now is travelling at 1/2 c and you are in it, watching the light beam bounce between A and B vertically. Everything is normal for you.

    But when you fly past your friend, who is looking at you from the ground. He would see weird things happening in your clock. The light beams of your clock will not appear to travel vertically. He’d observe that the light beam in your clock takes a diagonal path (in the direction of the spaceship) as it bounces from B to A or A to B.

    It is obvious that he observes it this way because the spaceship is moving too fast and the mirrors are moving along with the spaceship too. So the light’s path would be diagonal for ANY observer.

    The light beam as it appears to take a diagonal path, it also appears that it has to take a longer distance to cover. Due to this longer distance, the light clock in motion now ticks slower. Therefore time in the spaceship appears to be slower for your friend. This is known as time dilation.

    But for you, inside the spaceship, everything will be normal. And if you happen to observe your friend, it would appear that he is moving at 1/2 of c speed relative to you and you will observe his clock to be slower too.

    Now let’s talk about ageing in the context of special relativity!

    Say if you use that spaceship to travel to Proxima Centauri which is 4.2 light-years from Earth. You will be travelling at 1/2 the speed of light and it would take you 8.4 years to reach the star and another 8.4 years to come back to the Earth.

    For you, the time passed is all normal – 8.4 back and forth, so 16.8 years of your life has passed. But on Earth, as time is relative, the people on Earth would’ve experienced a different time, that would have ticked faster than yours — and hence they would be a few years older than you.

    Graph showing the relation between Lorentz Factor and Speed of Light.

    To have a significant change in the time delta, you’d need to be travelling above 75% of the speed of light.

  •   What would be the effects of the three states of matter happening simultaneously#9572

    Yes, it can. They can homogeneously change between one phase to the other at a particular temperature and pressure or exist as a. Thermodynamically, this particular temperature and pressure, at which a matter occur at all the three phases (solid, liquid, and gas), is known as the triple point. The following is the phase diagram of the water showing the triple point of water 273.16 K.

    Phase diagram of water.

    Illustration by Cmglee | CC BY-SA

    So at 273.16 K and 611.65 Pa, water exists as a homogenous mixture of solid, liquid, and gaseous phases, where any minimal changes to the temperature or pressure of the system can force a rapid transition between these phases.

  •   How to escape the ` character in HTML?#9553

    After experimenting with <code> and <pre>, I don’t think it’s easy to escape it. I settled with using the HTML entity for the ` grave accent. Here you go! sudo kill `cat /var/run/mysqld/mysqld.pid`. Use <code> tags to wrap it instead of ` `.

    escape grave accent in bbpress

    This is how I added it!

  •   At what stage in plants, a burst of light has the most effect on future growth#9547

    Your friend’s observation makes sense. Take a look at the absorption spectra of chlorophyll.

    The absorption spectra of chlorophyll shown as a graph.

    Daniele Pugliesi | CC BY-SA 3.0

    In the green range, the absorption rate is relatively low for the primary pigments chlorophyll b and chlorophyll a, which means the leaf reflects all the green light (the reason why plants appear green).

    But in the violet and red ranges, the absorption peaks and chlorophyll benefit the most. And your 440 nm blue light happens to fall under that spectral range called the photosynthetically active radiation (400 to 500 nm and 600 to 700 nm – your optimal wavelength), which promotes photosynthesis in plants.

    And to back your friend’s observation, here is a study on how the removal of green and near-UV radiation promotes plant and algae growth with visible improvements. Most of the plants have shown positive growth characteristics without the green light. For most of the plants, you could try it right from the germination phase.

    But mind the fact that plants have other pigments that benefit from the green light too. Also, as the green light penetrates deep into the leaves than the red and the blue regions, it enables the chloroplasts that are away from the illuminated surface to promote photosynthesis. More on this, here and here.

  •   Do CO2 molecules stop rising at a certain point in our atmosphere?#9543

    To answer your first part of the question, the CO2 barely rises in our atmosphere. The second part of the question, not likely.

    To a certain extent in our atmosphere called the turbopause layer, all gases exist as a homogenous mix of gases due to factors like turbulence from winds, thermal convection, and molecular diffusion. This region (homosphere) extends up to 100kms in our atmosphere to the turbopause. And within this region, the turbulence of the air dominates any stratification of gases.

    Take helium for example. It exists in our atmosphere in trace amounts–as a homogenous mix along with oxygen, nitrogen, argon, carbon dioxide, and other molecules in trace amounts in the homosphere. Whenever you introduce helium at the surface of the Earth (not as helium balloons) the molecules would tend to rise, but collisions with the other molecules, and stronger turbulent currents, convection, all work stronger to keep helium close to the Earth.

    But beyond the turbopause, the gases actually stratify based on their density. Hydrogen and helium, being the lightest would rise up. And for a gas molecule to leave the Earth’s atmosphere, it should require high kinetic energy and a longer mean free path (a huge space with no collisions happening) to overcome the escape velocity of the Earth. With the energy from the thermosphere and a large mean free path in the upper regions of the atmosphere, helium sometimes escapes Earth’s atmosphere.

    Now back to carbon dioxide (and methane – even more potent than CO2). They are heavy. Compared to helium, a carbon dioxide molecule is approximately 14 times heavier than helium and methane 4 times.

    As you see, methane would likely rise up than carbon dioxide. And when methane is oxidized in the troposphere, carbon dioxide is released along with water vapour. And for the CO2 molecule to blast off into space, it would require 14 times the energy of helium. And if the CO2 gains kinetic energy (14 times the energy required for helium), it would blast off into space. Or the solar storms would strip them away.

  •   How do I update the Windows 10 emoji set manually?#9535

    I don’t think you can just update the emoji set alone. It’s part of the feature updates.

  •   Easiest way to transfer files from PC to Android using Wi-Fi without internet#7536

    You can do that with FTP or SMB. You’ll need to set up an FTP server or enable file sharing on your computer to the folders you would like to share. And then you can access it from your Android with any FTP/SMB clients available from the app store. I’ve used AndSMB client and it does the job! Here is an updated overview on this.

  •   Weight of Baking Soda & Vinegar goes down when mixed, even when gas is captured#7513

    Hello Durran,

    Interesting question.

    The short answer for this is buoyancy.

    Long answer:

    When the flask and the balloon setup is placed, it is inside a fluid (air) medium. And as it occupies a certain volume, the setup would experience a buoyant force. (If the density of the whole setup is less (hypothetically) than that of the air, it will float way, of course. But in reality, the density is high, and so it sinks.) Now when the baking soda and vinegar in the flask reacts, the gas inflates the balloon. This increases the volume of the whole system, which makes it less dense compared to the previous state. As the density decreases, the buoyant force on it increases a bit, making it to weigh lighter than before.

    The law of conservation of mass is not violated here as the total mass remains the same, while the weight (mass × acceleration due to gravity) of the system is the one that changes.

    Hope it helps! :)

  •   What are some good online multiplayer games that are not pay to win?#7339

    Most games—the majority of free MMO games—are pay 2 win sadly. From the top of my mind, DOTA 2 is currently a free, play 2 win MMO that I played some time ago. You only need to pay for the cosmetic stuff. But then there is DOTA plus. But honestly, even the paid games are turning into pay 2 win these days with all that shortcut kits and other loot box craps. It’s a sad state of gaming today. So to answer your question, there are no online games these days that would qualify as a truly skill based play to win!

  •   Could a rocket flying below escape velocity leave Earth’s gravitational field?#7283

    You’re right. A rocket with enough fuel in it would eventually leave the Earth’s gravitational field, even if the velocity is less than the escape velocity. This is because the rocket’s engine is propelling it constantly with enough thrust to counter the effects of the gravitational pull.

    In the other hand, escape velocity is the initial minimum speed threshold required for an object thrown or launched upwards from the surface of the Earth so that the projectile would leave the gravitational field without the need for any propulsion or work. So if you were to launch a rocket at 11.2 km/s, it can theoretically leave the gravitational field of the Earth without any further thrust from the engine. The concept of escape velocity usually applies to projectiles (objects that are not powered).

  •   Chemical elements that would bond with Na+ or Cl- in a water medium#7280

    Hello Javy,

    Welcome to Geekswipe Curiosity. When NaCl dissolves in water to form Na+ and Cl, depending on the ions that are already in the water medium, there would be a lot of possibilities for the two ions to bond with other counterions to become neutral again. At room temperature and pressure, most of such reactions would be soluble in water for Na+ and Cl. However, Lead ion and chloride ion for example, would result in a partially soluble precipitate of lead chloride. And silver ion with chloride ion would result in an insoluble precipitate. You can refer this solubility chart for all possible reactions.

  •   Where do electrons come from in the light-dependent reactions?#6803

    When light is incident on the photosystem II, the electrons in the chloroplast molecules are excited. And when this energy is transferred to the reaction centre (via resonant energy), the electron acceptors remove the excited electron from the (special pair) chlorophyll and initiates the electron transport chain process.

    Also, due to photolysis, the water molecules are split into O2 atoms and H2+ ions. The electrons lost by the chlorophyll pigments in the photosystem II is replaced by these electrons lost (by the H2 atoms) in the splitting of the water. The H2+ ions then form the hydrogen ion gradient coupled with the electron chain, whereas the O2 atoms combine to form oxygen molecule that is released as a by-product.

    Further down the electron transfer chain, the electrons from photosystem II reaches photosystem I and is accepted by the already electron deficit chlorophyll molecules (The photosystem I would also lose electrons the same was like photosystem II) in the reaction centre of photosystem I. The lost electrons from photosystem I will go into making NADPH, further leading to create ATP.

    So to answer your question, the electrons come from a) excitation of electrons in the photosystem II reaction centre, b) splitting of water molecules due to photolysis, c) excitation of electrons in the photosystem I reaction centre.

  •   How did they film the car tracking shot in Zodiac movie?#9567

    Man! This film is a treasure. It’s got full of VFX stuff that blends in the right way.

  •   Is copper scientifically attracted to water ?#9562
  •   Easiest way to transfer files from PC to Android using Wi-Fi without internet#7538

    You’re welcome! :) And actually, this seems better! With an FTP client like Filezilla running on the PC, I can keep select folders in sync with the phone too. Especially my music library! Yay! You could try HTTP too! Should get interesting when you start running a server from your phone.

Viewing 15 replies - 1 through 15 (of 91 total)