What is Cold: Definition and 394 Discussions

Cold is the presence of low temperature, especially in the atmosphere. In common usage, cold is often a subjective perception. A lower bound to temperature is absolute zero, defined as 0.00 K on the Kelvin scale, an absolute thermodynamic temperature scale. This corresponds to −273.15 °C on the Celsius scale, −459.67 °F on the Fahrenheit scale, and 0.00 °R on the Rankine scale.
Since temperature relates to the thermal energy held by an object or a sample of matter, which is the kinetic energy of the random motion of the particle constituents of matter, an object will have less thermal energy when it is colder and more when it is hotter. If it were possible to cool a system to absolute zero, all motion of the particles in a sample of matter would cease and they would be at complete rest in this classical sense. The object would be described as having zero thermal energy. Microscopically in the description of quantum mechanics, however, matter still has zero-point energy even at absolute zero, because of the uncertainty principle.

View More On Wikipedia.org
Recent contents Top users
  1. daniel_i_l

    Why does cold air go to the bottom of the room?

    I was thinking to myself, why does cold air go to the bottom of the room and the hot air to the top? At first the answer looked simple, the cold air is "denser" than the hot air. But if you think about it, at the molecular level the only difference between hot air and cold air is that the...
  2. D

    Friend with Hepatitis B and Cold Body Symptoms

    can someone help please my friend has hepititis b and is feeling COLD throughout the body symptom his stomach hurts what is the illness?
  3. B

    The Feeling of Cold: Where Does It Come From?

    Where does the feeling of cold come from? Is it from heat rushing past cells, when we step outside in the cold, that creates this feeling we signal as cold?
  4. W

    Uncovering the Truth: Why Do We Get Sick in Cold Weather?

    A friend of mine were discussing the cold weather and how everyone's getting sick. I was then trying to figure out why exactly people to tend to get sick when it gets cold? I'm sure there some very logical explanation, but I could not for the life of me think what it was. Everyone knows your...
  5. wasteofo2

    Help coming up with a formula for determining weight lost in cold.

    When you're cold, your body naturally burns calories to keep you warm. So it makes sense to me that if people were to just stay out in the cold enough, that they could lose some weight. Also, it seems that you could probabally figure out a formula to determine exactly how much weight you'll lose...
  6. Pythagorean

    Exploring Physics Experiments in Cold Weather Conditions

    I'm a physics major in Alaska, where it's not uncommon to have temperatures of -40. Are there any interesting experiments or designs that I can do in my freetime that are convenient because of the cold weather? I remember learning briefly about gradients being a source of power. If...
  7. wolram

    Betting on a Record Cold Winter: What's the Forecast?

    The british press are forcasting a record cold winter, and a major betting company have slashed the odds for this. what are they basing their predictions on ?
  8. Garth

    The origin of cold dark matter halo density profiles

    http://www.arxiv.org/abs/astro-ph/0508624 This paper offers a fairly natural explanation for the universality of dark matter halo profiles. In this model the mass accretion history has two distict phases, first a fast phase dominated by frequent mergers of smaller condensations of CDM...
  9. R

    How can cold radiation heat?

    How can "cold" radiation heat? I have enough experience with steam radiators and heat lamps to know that they don't radiate enough heat to warm their surroundings to the temperature of the radiator or lamp. How then can ground and water emit radiation with sufficient energy to warm the air to...
  10. Q

    Why is hot wax thrown into cold water a dangerous combination?

    Hi, recently I found something out by playing around with candles. Basically I heated some candle wax until it was completely out of its solid state (at least through the first approximation of my eye.) Then I continued to heat the wax until the liquid wax ignited and started to burn. Usually...
  11. Pengwuino

    Does anyone know a good way to get rid of cold sores?

    Cold sore :( Does anyone know a good way to get rid of cold sores. I Have this one on my cheek and its so hard to eat!
  12. Reshma

    What Causes Common Cold? Investigating the Myths

    I have a weird question here :biggrin:. What exactly causes common cold? I'm aware it is caused due to viruses but why do doctors prescribe anti-biotics for common cold which are supposed to fight bacterial infection? Do the following cause common cold: *Eating ice-creams *Wet hair *Hot...
  13. Evo

    Cold medicine now a controlled substance

    Has anyone tried to buy over the counter cold or allergy medicine lately? A lot of states have just started enforcing a new law that restricts sales of most cold and allergy medicines. I just stopped on the way home to pick up a box of Actifed (the best thing in the world for allergies...
  14. A

    Reason of hot water 'float' on the cold water

    i think that the reason of hot water 'float' on the cold water is not becuase of diffrent density. i make a model of a container containing a higher energy particle (hot water) and lower energy particle (cold water) using action script in flash and uploaded it in geocities...
  15. M

    Indian scientist who claimed to have caused cold fusion in a lab

    Hey, I remember watching a program (Horizon - UK) on an indian scientist who claimed to have caused cold fusion in a lab. The program tried to recreate it (the procedures were not actually the same - but some big name scientists advised them which equipment would be used), and failed. I...
  16. M

    Exploring the Origins of the Flu and Cold Viruses

    Every year we hear about the flu season and the cold season without fail. Everybody is always so riled up about the flu. With good reason too. Now they have patented a vaccine that is supposed to prevent you from getting the virus. Makes sense to me. Vaccinate high risk people who could...
  17. S

    How does extreme cold weather affect speech and coherence?

    Hi. I recently went paintballing in muddy and snowy conditions (at the same time). I found a really curious thing happened to me. My words would get stuck in my mouth more often, I'd make pronuciation errors and I'd generally mess up words. For example, when I wanted to say: "Let's go!"...
  18. M

    Inverted the pipet into cold water

    ok in this lab, we heated a plastic pipet in water so that it expandes. then we covered the top so that the gases are trapped inside the pipet. then we inverted the pipet into cold water, and releases our thunb that covered the hole of the pipet. thus water got sucked in...but why? :uhh...
  19. Mk

    Skydiving Temperature: The Impact of Air Resistance on Body Heat

    I've never gone skydiving, but, if you jump off an airplane, will it be hot or cold, or neither? I was thinking, ram pressure and friction from the air would heat you up, though wind cools you off by carrying away heat... hot or cold?
  20. R

    Is Moisture Harmful to Telescope Lenses in Cold Weather?

    i just bought a telescope and i am in Canada it iz really cold outside and i want to take it outside to look at the stars but someone told me that moisture would get stuck in the lens and it would be ruined can somebody tell me if this is true personally i don't think it would but i don't want...
  21. T

    Is Cold Plasma Possible? Exploring the Energetic State of Matter

    I thought plasma was the most energetic state of matter, and that heat is proportional to energy levels? How is it possible for cold plasma then?
  22. D

    Laser Inquiry: What are Cold Lasers?

    Cold Lasers? Hi, I was overheard one of my profs talking and he was talking about cold lasers. I googled it but I could not find anything worth while. Does the laser "slow" down the electrons in the obitals? I don't really know how to approach this one... Does anyone know anything about this...
  23. R

    Could hot dark matter be cold dark matter?

    Could hot dark matter be cold dark matter? In other words did hdm cool and become cdm? And could hdm moving at or close to the speed of light exist beyond the most distant detected galaxies?
  24. W

    Cold Fusion Questions: Answers to Common Questions

    I am very ignorant on this subject and was just wondering a few things. What exactly is it (how do they do it), I am having trouble finding information on it. Why can't it be recreated, or was it really done at all? Also I was wondering what resources it uses to create the energy. Thanks
  25. M

    Iraq War: Cold cut argument.

    In a brainstorming exercise in my English 151 class a few weeks ago, my teacher told us to write down all of the things that we feel strongly about on a sheet of paper. I couldn’t write anything. As she requested our papers I hastily wrote down a few things, but none of them I truly felt strong...
  26. T

    Why is my bum itching after washing my jeans with cheap soap and cold water?

    I think I've figured out why I've been so grumpy lately. My bum has been itching like crazy. I don't think all the soap rinsed out of that last batch of Levi's I washed. I couldn't figure out why I had a rash on my bum and inner thighs, I hadn't switched brands of adult diapers recently, but I...
  27. brewnog

    The Cold Beer Dilemma: The Ultimate Conundrum

    Right! I don't actually have an answer here, so don't get your hopes up, but your thoughts please! I buy two bottles of cold beer at the bar, they're both taken out of the fridge and opened at the same time. I'm holding one in each hand. I can only down a few before my stomach gets full...
  28. X

    Ethyl ether can react with cold concentrated H2SO4?

    I wonder if ethyl ether can react with cold concentrated H2SO4. I think that it cannot react but I still not sure because my books don't say anything about temperature condition. What about heated concentrated H2SO4, can it react without water or alcohol just only conc. sulfuric acid. Thank you...
  29. marcus

    Is Avoiding the Central Issue Dishonest? The Truth About Cold Fusion's Return

    you decide the headline is something about Back from the Dead http://www.spectrum.ieee.org/WEBONLY/resource/sep04/0904nfus.html
  30. P

    How do the Casimir force and cold welds relate?

    What is Friction? Making contact amounts to the mutual repulsion of electrons on each body's surface. So is friction the lateral repulsion experienced as a result of surfaces not being smooth? In other words, the surfaces have roughness and so 'fit' into each other whereupon the electrons can...
  31. R

    Reigniting the Cold Fusion Debate: MIT Professor's Quest

    http://www.boston.com/news/globe/health_science/articles/2004/07/27/heating_up_a_cold_theory/ QUOTE: COLD FUSION Heating up a cold theory MIT professor risks career to reenergize discredited [...] So over time, cold fusion scientists have become members of a small...
  32. F

    Questions on the common cold virus

    1) How long can this virus last between hosts? 2) When you "get better", what is actually happening? has your body overcome the virus's replicating abilities? evicted it? "killed" it? 3) Can the same virus re-infect one right away? like, say you've just had a cold, gotten better, and then you...
  33. K

    Is Cold Fusion Possible with Palladium and Heavy Water?

    how about cold fusion? I know it's got avid supporters as well as those who say it's total B.S. last I heard, it had something to do with the way Palladium acts in hard water... I'm going to go look some of that up. I want input! anyway, i hear it's possible. edit: thanks...didn't even notice...
  34. O

    Haarp Weapon, and Europe's Cold Summer

    The cod have moved off the coast of Sweden, due to fluctuations in the jet stream. Five miles of nets producing ten pounds of fish. A summer that is the coldest since 1847, and if it doesn't warm up soon, it will be the coldest since the 1700's. The Butterfly Theory talked about even minute...
  35. shintashi

    Is Cold Fusion a Feasible Energy Source or a Dangerous Concept?

    Over the past year, I've evaluated my own research and observations and matched them up with some statements from a pair of friends. One worked on a nuclear sub, and the other worked on an aircraft carrier. Both worked in the nuclear engine rooms. As I've been refining the concept of...
  36. R

    Is photosynthesis a form of cold fusion?

    Well Dr. Kaku?
  37. Z

    Exploring Cold Welding: Understanding Friction and Surface Roughness

    If I'm understanding it correctly, my book says that frictional forces are the result of cold welds - that when two surfaces are in contact with one another, the highest points on the surfaces on an atomic scale weld together to form a single object, and these welds are what resists movement...
  38. Antonio Lao

    Hot & Cold: Understanding the Universe

    If scientists understand hot and cold completely then high temperature superconductivity will become a reality and cold fusion is just child play. Until then, we can do all the theorizing we want but to really understand the universe we must understand what is hotness and what is coldness...
  39. wasteofo2

    Water evaporating from my hand in the cold.

    Recently I was playing in the snow without gloves. I made a snowball and the residual water on my hand began evaporating and was visible, much the way your breath is in the cold. Why did the water do this?
  40. R

    Do cold blooded animals do best in cold weather? or hotblooded?

    i wasnt sure where to post this... but I've been really curious about this since i am always the one that isn't cold... I was wondering if the animals that live in cold weather are hotblooded or cold blooded... like penguins for example and if there really is a pattern. also i was...
  41. F

    Uncovering the Truth Behind Cold Fusion: Separating Fact from Fiction

    So what is the deal with cold fusion these days what is hindering the progress of an ubundace of energy? Please Explain [?]
  42. Z

    Exploring Cold Fusion: Accelerator Smashing and Deuteron Collisions

    why they don't use good ol' accelerator smashing? bring two deutrons to couple of KeV (witch is not a particular problem) and collide them in some vacuum chamber. same charge repulsive force will be couple of magnitudes smaller than force on paticle under acceleration, so where's the problem?
  43. V

    Exploring Cold Fusion's Possibility: USA

    Having read my Command and Conquer Generals book I have seen that the USA use Cold Fusion. Is this theoretically possible and could it be done in the future and if so how would it work?
  44. J

    The Possibility and Potential Implications of Cold Fusion

    Do you think that cold fusion is posible? Also, if it is what would some of the implications of this be, how would it change our world?
Back
Top