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Nicholas Kang

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  1. Ok, though I don't take biology now after high school. I still remember what I learn. This is more of a biochemistry question. The explanation is simple. First, you need to understand what is osmosis, osmotic pressure and how osmoregulation works. Osmoregulation (See:https://en.wikipedia.org/wiki/Osmoregulation) is basically the regulation of an organism's body water content to maintain its osmotic pressure. You also need to understand the term endoosmosis, exosmosis, hypertocnic and hypotonic etc. Ok ,we start with the simple ones first. 3 types of solutions exist: solutions hypotonic to cell, solutions hypertonic to cell or solutions isotonic to cell. Say you place an animal cell into a solution that is hypotonic to the cell. The hypotonic solution means that is has less solute in the solution, thus less concentrated and has lower osmotic pressure. So, relatively, the cell has higher osmotic pressure, and water flows across the cell membrane from the outside (solution) to the intracellular space (inside the cell). The cell will accumulate water over time and swells and may eventually burst. The opposite happens to the animal cell when it is placed in a hypertonic solution. It has high solute content and thus more concentrated. So, an animal cell immersed in it tends to lose water to the surrounding, and the animal cell shrinks in size. For an erythrocyte (Red blood cell), it is said to crenate. For plant cell, the condition differs a bit, given that plant cells have cell walls, which is absent in animal cells. Plant wall gives the plant cell strength. So, when a plant cell is immersed in a hypotonic solution, though water enters the plant cell, the plant cell would not burst, but remain turgid, i.e. the vacuoles are large and the plant cell is stiff. However, if immersed in a hypertonic solution, the plant cell will lose water like an animal cell, thus shrinks in size, and we say the plan wilts. If the dry condition is prolonged, it leads to the death of plant. An isotonic solution is the solution which has the same solute concentration as that of the organism's body. Hence, it is the optimum condition for an organism to live in and the cells won't lose or gain any water, and hence no change in the organism's body size is observed. Here is a website that teaches you the 3 concepts. http://www.phschool.com/science/biology_place/biocoach/biomembrane1/solutions.html --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- So, given such extremes condition, organism (composed of cells) learn to adapt themselves to their surrounding environment. In you question, saltwater fish is the organism in question. Saltwater fish lives in a hypertonic environment, that is their surrounding fluid (sea water) has high salt content, thus hypertonic to the cells in saltwater fish. If no preventive measure is taken, the cells will loss water to its surrounding quickly and they will die due to lack of water. So, one way to overcome this is to increase the organism's body salinity to make them even more concentrated to the surrounding environment (seawater in this situation, or any salty aquatic environment). Now, it is their bodies that are more hypertonic than the surrounding salty water, thus instead of losing water to the surrounding, they gain water from the surrounding. So, the answer to your question is A. Good luck with your studies!
  2. Ok, I think I need to further clarify my case. I don't mean someone just sits on lunar surface and watch Earth wobbling. I mean, get yourself up and high away from lunar surface and stay idle there, see how Earth moves around the Moon. In my test, it does "orbit" around the Moon this way (Moon is observer, Sun is focus, hence Earth is moving): Then, Earth to the right And finally it is between moon and Sun Closer view: Earth is missing which proves that it is really between Moon and Sun. Then, Earth to the left And finally back again (Moon between Earth and Sun). Earth completes one "orbit" around the Moon. Earth does not cover the Moon because Moon is not coplanar with the ecliptic. (That's why you don't have solar and lunar eclipse every months. They only happen when they are collinear.) Here is the orbit plot diagram that I mentioned. My friend told me the white line is Earth's orbit plot. So, I want to know whether the orbit plot diagram is correct or not. In my case, I want to get from low lunar orbit to Earth-moon Lagrange point 1, so the yellow circle is the Moon and the green line is my planned trajectory, but I wonder what the white line is. My friend said that is Earth's trajectory as seem from Moon. So I want to know if that is really the case. And if he is correct, what is the orbital period of Earth around the Moon as seen from the Moon then? Thanks for answering. Nicholas.
  3. Hello I am working on an orbit trajectory plot tool with my friend from the US. I have some question to ask all of you about this question. In our trajectory plot, we would like to fix Moon as the center of our orbit plot. Then, from our perspective (the moon), what would the Earth's orbit be or look like? From the moon's perspective, would the Earth seems like orbiting the Moon? If this is the case, how long does it take for Earth to "orbit" the Moon? The same period as lunar's orbit, i.e. 27 days? Thanks for answering. Nicholas.
  4. Ok, Sensei. In the diagram, Cl atom is larger than B atom. Now, BabcockHall says he thinks Chlorine's orbitals will not (unsure) overlap effectively with the orbitals of boron. So, what do you think, Sensei? What is your opinion? (Simply put, what is your answer to my question? )
  5. Well, this question is basically about mechanics, work and energy. There is no need to use suvat in this case. Strategy: Height already given-Hint: gravitational potential energy Speed given-Hint: kinetic energy Ok, apply principle of conservation of energy at both A and B Assume you already know the basic knowledge: EK = 0.5mv2 , EP = mgh, Assume g=10 ms-2 and let Fc = Frictional force, then EK at A + EP at A = EK at B + EP at B + Word done against friction 3(10)(6) + 0.5(3)(4)2 = (3)(10)(2) + 0.5(3)(8)2 + Fc(12) So, solve for Fc , you get Fc = 4N That is the frictional force is 4N. ------------------------------------------------------------------------------------------------------------------------------------------------------------------------ Now, again using the same concept, we can find how far will the block be when it stops, hint: final energy= Energy required to counteract frictional force. Ok, Total energy at B= total energy at A + work done against friction from A to B = total energy done to do work against friction when the block has stopped 3(10)(6) + 0.5(3)(4)2 = 4(Distance) Total distance traveled by the block until it stops = 204/4 = 51 meter But this distance include the distance from A to B, which is 12 m. So, distance traveled from point B to the point where it has stopped is (51-12)m or 39 m. OR If you choose to start from point B, then (3)(10)(2) + 0.5(3)(8)2 = 4(Distance) Distance = (60 + 96)/4 =39 m, which is the same answer as above. ------------------------------------------------------------------------------------------------------------------------------------------------------------------------ Remember, more practice is essential to develop an instinct that helps you solve Physics problems rapidly. But make sure you master the theories first before you begin. Good luck with you studies!
  6. Are you sure? I thought Boron is larger than Chlorine. The atomic size of elements decreases across a period. And I have checked the atomic radius for both Boron and Chlorine. Boron: 87 pm Chlorine: 79 pm So, apparently, Boron is larger than Chlorine.
  7. Can you explain it in detail? How does electronegativity affects hybridization?
  8. Ok, finally someone replied. Thanks fiveworlds. Personally, I think this configuration is more stable, since hybridisation stabilizes a molecule. Apparently, if achieving octet or duplet is the only thing required for the formation of a particular molecule, why would you hybridise the central atom as well? So, it is clear that you hybridise atoms of molecules to make them stable and hybridise all atoms would definitely make the whole molecule stable. Am I wrong? Nicholas.
  9. I have been offline for almost 2 years and now I am back. I hope you guys still remember me... Here is a question on physical chemistry. Simple question. It is about Valance Bond theory and the use of hybridisation/hybridization (depending on whether your English is American/British variant) concept. My teacher taught me how to explain Boron trichloride's structure using VB theory. Boron atom undergoes sp2 hybridisation. Each sp2 hybrid orbitals will have an unpaired electron that will be shared with the unpaired electron in Chlorine's 3p orbital. So, the orbital overlap diagram looks like this. (Check the attached file.) The 3 red orbitals are the 3 sp2 hybrid orbitals while the 3 green orbitals are from Chlorine's 3p orbital. My question is why Chlorine does not undergo hybridis(z)ation as well? Supposedly, each Chlorine atom should undergo sp3 hybridis(z)ation to produce 4 sp3 hybrid orbitals, one of which is shared with the sp2 hybrid orbital of Boron atom. So, 3 sp3 hybrid orbitals from 3 Chlorine atoms share 6 electrons with 3 sp2 hybrid orbitals from Boron atom. Thanks for answering. Glad to see you guys again. Regards, Nicholas.
  10. Here is another one. Falcon 9 carrying OG2 in its fairing poised for launched at KSC. Thanks for enjoying the screenshot. Regards, Nicholas.
  11. Hello, I have not been around SFN for quite some time. I was focusing on my studies and also flying to different orbits using Orbiter Space Flight Simulator. Nice to see all of you again. Here I would like to start a new thread for those who use Orbiter and love to share their beautiful screenshots. I will start first. Here are 2 (beautiful, or maybe opposite; beauty is in the eye of the beholder) screenshots captured using Orbiter. The first is ThaiCom 8 launched to elliptical transfer orbit after SECO of Falcon 9. The second is GAIA of ESA in Largrange Point 2 or L2 after launched from Kourou Spaceport aboard a Soyuz rocket. The black disc covering the Sun in the GAIA mission screenshot is Earth. Hopefully you enjoy the view. Regards, Nicholas.
  12. I shall give it a try. Let's deal with the equations first. You had followed what studiot said. So, solve the three equations. (In Malaysia, we are taught that general quadratic equation is ax2+bx+c=0; we don't use z in place of c) 4a-2b+c=0--EQ1 16a+4b+c=0--EQ2 9a+3b+c=0--EQ3 EQ1 x2-- 8a-4b+2c=0 4b=8a+2c Substitute 4b=8a+2c into EQ1 You get: 16a+8a+2c=0 24a+3c=0 3c=-24a c=-8a Substitute c=-8a into EQ1 You get: 4a-2b-8a=0 -2b=-4a b=-2a Substitute b=-2a and c=-8a into EQ3 9a+3(-2a)+(-8a)=-15 9a-6a-8a=-15 -3a=-15 a=-3 Substitute a=-3 into b=-2a and c=-8a You get a=-3, b=-6, c=-24 Quadratic equation is 3x2-6x-24=0 To get the minimum value, I invoke the method of completing the square (This was taught in Form 4, 16-year-old syllabus in Malaysia) To complete the square, first you have to understand how it works. Let's say we have quadratic equations: (x-1)(x-1)=0 (x-2)(x-2)=0 (x-3)(x-3)=0 So, x2-2x+1=0 x2-4x+4=0 x2-6x+9=0 Notice the pattern of the above 3 equations. You can conclude: x2-2x=(x-1)2-12 x2-4x=(x-2)2-22 x2-6x=(x-3)2-32 So, x2-nx=(x-n/2)2-(n/2)2 Now, 3x2-6x-24=0 3(x2-2x)-24=0 3[(x-1)2-12]-24=0 3(x-1)2-3-24=0 3(x-1)2-27=0 After completing the square, you will obtain a formula that looks like a(x-s)2+v=0, where s represents the axis of symmetry and v represents the minimum/maximum value of the function/equation In this case x-1=0 thus axis of symmetry is x=1 whereas -27 is the minimum value of the equation. The answer is -27. (I posted a link in case you need some references. The link below directs you to a Malaysian Form 4/16-year-old Malaysia Education Certificate Syllabus-based Additional Mathematics website. Look for Chapter 2(quadratic equations) and 3(quadratic functions) for details.) http://spmaddmaths.onlinetuition.com.my/
  13. studiot, I can roughly figure out where are you leading me to. Also, based on your last assumptions and what pavelcherepan had said, you must be talking be about thermal equilibrium with the surroundings. So, the final temperature must be equal to the temperature of the surroundings instead of just 10 degree Celsius. Is this what you mean? If so, this question must not be talking about a closed system, it must be an open system if you talk about surroundings.
  14. Assumptions based on studiot. Good assumptions, studiot. At least you "fill in the gaps required." Solutions: Picture the problem Imagine an ice cube being placed in a glass of water. Ice cube is 0 degree Celsius. Water is 10 degree Celsius. We know that heat is transferred from the water to the ice so that thermal equilibrium is reached somewhere between 0 and 10 degree Celsius. So, we assume: heat absorbed by the ice = heat released by the water, that is, Qabsorbed = Qreleased We first assume that all sensible heat is removed from the water before latent heat of water sets in Qabsorbed Qreleased micelfusion mwatercwater(10-0) mice(334000 J/kg) 0.225(4180)(10-0) mice(334000 J/kg) 9405 J Now, we know the heat supplied when the water cools but not freeze at a constant temperature is 9405 J. Yet, some 334000 J of heat is needed to melt 1 kg of ice. So, we know the heat supplied supplied by the cooled water isn't enough. But thermal equilibrium is achieved since both the ice and water is 0 degree Celsius. The ice starts off at 0 degree Celsius and the water has cooled to 0 degree Celsius. No net heat flow occurs between 2 bodies. Thus, the temperature remains constant. The answer is 0 degree Celsius. You can check how "light the ice might be" by using the formula Q=ml, that is 9405=mice(334000) mice=9405/334000 =0.02816 kg, about 28.16 g of ice would be sufficient to absorb all 9405 J of heat and remains at a constant temperature with the cooled water. *I ignore the surrounding temperature in this case. Before you consider my answer, studiot, is my answer correct? I am a high school student and after reading the question I think I can answer it. Anyway, you should consult studiot first.
  15. As a high school student still in the process of learning, I, Nicholas Kang would like to express my utmost gratitude to Dr. Tom Swanson for his meticulous teaching. Thank you Dr. Tom Swanson. You make my day. Anyway, I don' think the above post was a bad one. You see, I have studied painstakingly to comprehend Relativity, at least to some degree. (No, I am not asking for praise or anything in return, just a statement) Not all high school students can study modern physics and classical physics at the same time, especially when they need to go through the hardships of choosing either fields when answering high school exam questions. You would feel the pain of "betraying yourself" when writing wrong or "inaccurate" answers, as some might argue that classical physics isn't the big blunder of physics after all. Well, Dr. Swanson, is there any more errors in my post? Feel free to correct it. It's nice to have a teacher like you. Thank you. Your mentee, Nicholas Kang
  16. Both mass and energy should be considered when one needs to solve relativistic equations and problems. According to Einstein`s Theory of Relativity, for an object with rest mass m, its energy is given by the equation E=mc2. Although E=mc2 is the World's Most Famous Equation, there is one point noteworthy. When an object moves, its mass will increase (though by a minuscule amount at insignificant speeds). The increase in mass can be determined by the following equation: E=mc2 times gamma factor OR E=mc2/square root (1-v2/c2) The gamma factor or Lorentz factor determines the values of energy and mass. If you express the speed in question in the form of a fraction of c, the constant c drops out of the equation, thus the formula becomes: E=m/square root (1-v2) This "modified" equation facilitates calculation. For an object travelling at some 87% of the maximum speed of light in vacuum or c, the gamma factor is 0.5. You get twice the mass for an object travelling at 87% of c. You can also calculate relativistic kinetic energy from this equation. Kinetic Energy=Total energy-Rest Energy or Ek=mc2/square root (1-v2/c2) - mc2 Now, I would like to talk a little about the mass-energy equation's history. According to Ira Mark Egdall's book, Einstein Relatively Simple, the equation E=mc2 actually comes from the classical Newtonian Kinetic Energy Equation. Please kindly refer to Egdall's book. Here is the historic paper we will never forget. Try to follow his thought experiment and Enjoy Physics. https://www.fourmilab.ch/etexts/einstein/E_mc2/e_mc2.pdf
  17. It is not too late too learn even in your 40s. You can start from the basic and then proceed to the complex ones. First of all, which level are you in right now? You have to ask yourself this question. I believe you should understand Newton's law by now. You should start from classical physics before moving on to modern physics. Physics goes complex as you continue conducting researches. The field diverges into many disciplines but nowadays interdisciplinary studies are taking center stage. Although the many-discipline-subject makes it hard to learn, they share a common root. Basically, you need to know: Mechanics Optics Wave science Electricity and electromagnetism Radioactivity Here are some of the GCSE level knowledge I know (Please take note maybe some of them are outdated, sorry.) Mechanics includes statics and dynamics. You get to know the forces in nature, how are they balanced and solving problems related to practical applications. You are introduced to types of energy, efficiency of machines, moment of forces, elasticity and momentum. In Malaysia, we study pressure as well. This includes relationship between Force, Pressure and Surface Area in Contact, Pascal Principle, Bernoulli's Principle and Archimedes Principle. Optics involves the study of properties of light. You need to know reflection, refraction, total internal reflection and critical angle. you should master the terminologies involved like focal point, principal axis, center of curvature etc. Wave science involves the study of waves and its properties like diffraction and superposition. You will learn that light (visible light) is a type of electromagnetic wave as well. Thus, you will study reflection and refraction again albeit applied in a much wider field -- All waves. Electricity and electromagnetism involve the study of electric field and magnetic field. You study Ohm's law, parallel and series circuit. You study interactions between electric and magnetic field as well. Electronics, another related field deals with how semiconductors, transistors and diodes work. Radioactivity deals with the emission of radioactive rays, namely alpha, beta and gamma rays, their properties and instruments to detect them. You will study the half-life concept, the nuclear fission and fusion processes and finally how nuclear power stations work. The most thrilling activity here is you stand a chance to apply Einstein`s equation-- E=mc2. Then from here you can further study other advanced concepts that are related to classical physics. You must have heard of relativity and quantum mechanics. What are they? Here is a good online book recommended for you. Be sure that you have grasped the basic concepts. http://www.feynmanlectures.caltech.edu/ Have fun with Physics.
  18. Woo... Sorry, I don`t mean to hurt all of you. Gees, thanks for your explanation. My mom did explain to me a few days ago when the judgement was made by the US Supreme Court. I regret not to edit my post (I posted it last year, long before the Judgement). I cannot predict future, thereby unable to know the Court`s Judgement. Sorry. really sorry. I beg your pardon, please, I am not intended to hurt all of you. Please forgive me, really. I am too young to understand this. I regret to post in the wrong section in this forum. I should think twice before posting. Please don`t -1. I beg your pardon. Please. I promise you this wouldn`t happen again, really. You see, I am just a 16-year-old and eager to express my own idea, but definitely not going against anyone`s point of view. Can you adults please forgive me, a little child still in the process of learning. Thanks you. Really sorry. (I give you all +1, I appreciate your points, except a few due to computer errors. I don`t know why I cannot give both Phi for All and sunshaker +1. I give you my word I will give both of you +1 later. Trust me) Sorry. Learning from all of you, mentors. All posters mentee, Nicholas Kang
  19. Yes. By obeying the three principles of sustainability. In a sustainable earth, economic decisions are not dominated but they must share equal importance with ecological decisions. When you cut down trees, you have to think of its ecological impacts to the environment. When you fight for Green Campaign, you have to think of the poor. Perhaps money donated and used by the poor can help them survive, and maybe if they are well-educated, they can make the Earth a greener place. Many factors must be considered. Usually, when you learn economics, you learn capitalism, accounting and making financial decisions, and when you learn ecology, you learn conserving energy, preserving floras and faunas, keeping the earth green and anti-plastic movements. But when you learn sustainability, you learn both, and most importantly, to balance both aspects, both economy and ecology. Be wise, be prudent and be green, be far-sighted at the same time. Take oil magnates. They are rich but they aren`t far-sighted, though. Automobile makers are far-sighted, Nissan, Toyota, Honda are competing to launch green, hydrogen fuel-powered vehicles or perhaps electric cars like Tesla Model S (my favourite). If oil peters out, who win the game? BP? Shell? No, it is those who will foresee a day when oil extinct from Earth and most importantly, take actions. Sustainability is not saying that you cannot use oil or cut down trees but you have to think of its replenishment rate. Say you cut down 5 trees per day. But the trees replenish at a rate of 10 trees per day. Net replenishment rate? 5 trees per day. Do you terminate trees? No, because 5 more are left per day. But the problems kick in when you cut down 20 trees per day. You gain Net loss of 10 trees per day. The same can be said about oil drilling. Most people think of crude oil as non-renewable energy source. In fact, oil replenishes over years, millions of years, perhaps at a slow rate. Organism die every day and earth plates move beneath you silently (except volcanic activities, earthquake and tsunami), oil forms under immense pressure and temperature. The problem? Simple. We use more than they form. If we could use less, they will have enough time to replenish. Less. When do you consider less? When do you consider more? Check these facts and numbers out. Resources: Biodiversity Rate of replenishment: 20,000 years for evolution to create 20 species Rate of Use or Degradation by Humans: 20 species of mammal extinct in 20th century Ratio of Use to Replenishment: 1000:1 Resources:Crude oil Rate of replenishment: 0.8 million barrels per year created by geologic processes Rate of Use or Degradation by Humans: 30 billion barrels per year used by global economy Ratio of Use to Replenishment: 31000:1 Resources: Tropical forests Rate of replenishment: 1 million hectares of humid tropical forest regrowth per year Rate of Use or Degradation by Humans: 5.8 million hectares oh humid forests cut per year Ratio of Use to Replenishment: 5.8:1 Resources: Fertile soil Rate of replenishment: 1 ton/hectare of new soil created Rate of Use or Degradation by Humans: 16 ton/hectares eroded from US farmland per hectare per year Ratio of Use to Replenishment: 16:1 Source: Kaufmann,R. and Cleveland, C. (2008). Environmental Science. New York, USA: McGraw-Hill From the data above, we can conclude that we rarely think rigidly in terms of ecological decisions. We use those resources, albeit not environmentally sustainable. This is the state of our planet, seen through numbers and statistics, not just mere words. Talking about evolution? Evolution is a change in heritable traits of biological populations over successive generations. (Wikipedia) Now, organisms and living things evolve over time. In that period, physical and chemical settings alter their biological state and when genes are passed down, their heirs will inherit them. The problem is humans are greedy and selfish for many years. Even evolution couldn`t have stopped them. But don`t forget about animals and plants, even though they don`t exhibit humanlike characteristics, they are important in the ecosystem. We, human should therefore, think of consequences. it is cruel to dominate this planet, for you won`t find something to eat, unless you prefer synthetic burgers to McChickens. You won`t be mesmerised by the beauty of nature, for no more trees exist, unless you fold some paper trees, giant paper trees behind your yard or garden. Would you imagine such a world without living beauty, not to mention botanists and zoologists would be jobless as we, people don`t need them (except from studying their fossils in museum)?
  20. I don`t really understand why nobody mentioned "gravitational wave". As far as I know, there are 2 possible outcomes. First, if the black holes are of similar sizes and are spinning, they may not merge at all but violently recoil, sending one of the pair hurtling away. If, however, the black holes do indeed coalesce, enormous amounts of energy would be released and massive ripples, called gravitational waves, would be sent through space-time. So far, however, no instrument has yet detected these tell-tale gravitational waves. Famous one includes LIGO. If I recalled correctly, there is a similar question being asked before in BBC Knowledge Asia Edition. I knew the above information from there.
  21. Compare with Hello, Mordred. Can I ask you one question? By comparing the 2 sections in the above quotes, what if the universe is rotating and we haven`t know it yet. Then shouldn`t we (cosmologists) come up with a revised or maybe totally new principle to explain that, instead of keeping on agreeing with the "old" cosmological principle?
  22. What you are saying is actually Hinton`s Cube. Hinton`s Cube is actually one way to visualize higher dimensions by using the analogy you had posted. However, we, humans, are born into his world with 3-dimension judgement. Usually, we only feel length, width and height. Our common sense tells us this piece of information is enough for us to articulate this world. However, we lack the time dimension. By using time as an additional tool, which is the fourth dimension, we can thus write history and keep information flowing from the past to the present. This is done by Einstein in his masterpiece, the General Relativity, which takes time into consideration when dealing with physical quantities like length, mass and time itself. So, according to GR, mass-energy affects space-time. Time, the fourth dimension, might has its geometry altered, just like what we do in our 3D world. We don`t realize it because we are not living at the maximum speed of light in vacuum, c. Only atomic clocks, flying rockets and massless particles running in space, particle accelerators and laboratories reveal the truth of nature. Talking about the plane you mentioned, I agree that the analogy and visualization is good but practically, you are not going to step on it. Really, I mean with current technology. To create such dimension, or more accurately, to traverse through such a high dimension, you need enormous energy, negative energy, which are found on Earth but in trace amount. Do you know about the Casimir Effect? Then you probably know negative energy well. According to some non-fiction articles (but quite technical), negative energy is actually used to stabilize the wormhole, which connects different dimensions. With enough negative energy, you may keep the wormhole open, and presto! You may now travel on the cosmic highway. Also, have you heard of Kaluza-Klein`s Theory or Superstring Theory? They deal with hyperdimensions too. The plane might go infinite. You could have continued stacking one on another to infinity. But if I recalled correctly, only 10 dimensions are needed to describe all 4 fundamental forces in nature. Currently, 3 forces have been united under Quantum Mechanics, leaving the "stubborn" gravity in the realm of general relativity. However, to quantize gravity is no easy task. You can`t just simply attribute a particle for gravity and name it gravitons. In fact, gravitons are not yet found. Contrary to GR, quantum mechanics allow probabilities to exist when Heisenberg`s Uncertainty Principle kicks in. You can`t say gravity exist here but not there. And unlike electromagnetic field, universal gravitational field results in the collapsing of the universe. So, most theoretical physicists speculate superstring theory is the last option, or maybe not (if you are the next Einstein?)
  23. As far as I am concerned, your answer has to do with the geometry of our universe. It all depends on the critical density of our universe. If observations find out that our universe overall mass-energy density exceeds the critical density, then our universe will stop expanding and contracts, which will come to Big Crunch. If the universe`s overall mass-energy density is exactly 10-23 g/m3 ,then our universe`s expansion will slow down. If the mass-energy density is lower than the critical density, then our universe will expand at the same rate forever. The mass-energy density determines the curvature of space-time, which in turns, dictates the fate of our universe. There are 3 configurations, namely open, flat and closed, which are named in accordance with the three conditions I mentioned above respectively. In an open configuration, the overall curvature is negative and 2 beams of light will diverge-the distance between increasing over time. While in a flat universe, 2 beams will remain parallel forever. In a closed configuration, a single beam of light will eventually curve around the entire universe and return, hitting you on the back of the head. Now, the question is, what is the overall curvature of our universe? Well, a number of observations by looking for clues in the Cosmic Microwave Background Radiation has shown that our observable universe is flat. Currently, astronomers have found out that our universe is not only expanding, but the expansion is accelerating as well. To explain the mysterious force that accelerates the expansion, astrophysicists turn to their friends-particle physicists to search for undiscovered particles in particle accelerators, like the LHC in CERN, Europe, which is restarted recently. So, I personally think that you needn`t have worried so much. Based on the rate of current scientific development, I believe we will have enough time before the worst. I have something to share, though, that is, escape to another universe through white holes during the last moments before The Worst. Such idea was explored by Michio Kaku, a theroetical physicist in his book Hyperspace. Maybe you have left out the "multiverse" concept. You can seek shelter in another universe, can`t you? Let`s hold hands and keep our fingers cross.
  24. First, which organelle in the cell contains the most hydrolytic enzymes? The answer is lysosomes. Lysosomes contains hydrolytic enzymes to digest and eliminate worn-out organelles and for extracellular digestive enzymes like pepsin, amylase and lipase, they contain hydrolytic enzymes to digest food particles. Thus, lysosomes yield the most in terms of cellular activities in that particular mammalian tissues, which is composed of many similar cells. hydro means water, lytic (lysis) means break down. Complex nutrients undergo hydrolysis to form simpler molecules that are readily absorbed by the body. Thus hydrolytic enzymes catalyze the process of digestion. Mitochondria provide the energy needed for digestion. Nucleus control the activity while ribosomes which are involved in synthesis of protein are inactive because the enzymes produced are already in action-digest/hydrolyses food. No new proteins are needed.
  25. I think you should try Richard Feynman`s Lectures on Physics. www.feynmanlectures.caltech.edu/ That covers topics from basic physics to complex mechanics. Have fun.
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