Subtitles section Play video Print subtitles It's AumSum Time. Can you guess the title of my next video? Hurry up. Write your guess in the comments section below. Are Einstein's gravitational waves real? No. They are waves created by Titanic. As always. You are wrong. Gravity is the attractive force with which two objects pull each other. However, Albert Einstein imagined gravity as well as space and time a little differently. His theory of general relativity unified two separate entities. Space and time into a single entity called spacetime. Spacetime can be considered as the fabric of universe. Now, just like a heavy ball creates a curve or distorts the trampoline, mass of an object creates a curve in spacetime. According to Einstein, this curve is gravity. This trampoline is amazing. First listen. Just like our hands create ripples in water, moving objects create ripples in spacetime. These ripples are termed as gravitational waves. Gravitational waves were directly observed for the first time on September 14, 2015. By Laser Interferometer Gravitational Observatory in the US. Why can't dogs eat chocolates? Because I would love to have all the chocolates for myself. Alright. Now listen. Chocolates and other cocoa products contain a toxic component called theobromine. The darker the chocolate, the more theobromine and the more it is harmful. But I eat chocolates. And I'm completely fine. Our body quickly metabolizes the theobromine. Thus, it is not quite harmful for us. However, dogs process theobromine much more slowly. So, it stays in their bodies for a longer time, resulting in vomiting, diarrhea, etc. Moreover, if large quantities of chocolate are ingested by the dog, the effects can be much more severe. The heart rate of the dog might beat twice its normal rate, increasing the blood flow. This can prove to be lethal to the dog. Why does February have 28 days? Many centuries back, a Roman King called Numa. Made a calendar according to 12 lunar cycles which approximately take 354 days. But as even numbers were considered unlucky, Numa rounded off days to 355. He also made each month odd-numbered, leaving one month, i.e., Februaries with 28 days to reach the total of 355. But as the earth takes 365.24 days to travel around the sun. Seasons and weather conditions started mismatching with the 355-day calendar. Then came Julius Caesar who decided to follow the solar calendar of the Egyptians that had Januarius and Februaries in the beginning. He made the calendar into 365 days by adding days in each month except February. As still 0.24 days were pending each year, after every 4 years. He added 1 day to February, making it a leap year. Thus, February has 28 days except during leap year. Why does sunlight make you sneeze? Because sun teases our nose. No. Wait. I'll explain. Sneezing caused by sunlight or bright light is called photic sneezing. According to a prevailing theory, it happens because of a thick nerve bundle called the trigeminal nerve. The trigeminal nerve detects or senses irritants in our nose and thus, triggers sneezing to expel them out. The trigeminal nerve lies quite close to the optic nerve which sends visual information from our eyes to the brain. Now, in some people this optic nerve is over sensitive. Just like me, right? Just listen. When bright light suddenly stimulates the optic nerve. The optic nerve mistakenly transmits some signals to the nearby trigeminal nerve. Hence, the trigeminal nerve misinterprets this signal as an irritant in the nose. Thus, triggers sneezing. Topic: Ignition Temperature. Why does a match light when you strike it? Why don't you use a match instead? You will be able to light the bonfire easily. No. I don't believe you. Try it. Look. I told you. That was awesome. This happened because of low ignition temperature. Ignition temperature is the lowest temperature at which a combustible substance starts burning. Lower the ignition temperature, more easily will it catch fire. Now, a match head contains antimony trisulfide and potassium chlorate. Enough. I know how to use it now. No. The match will not light on any surface. The rubbing surface of a matchbox has powdered glass and red phosphorus. On striking the match against it, friction is caused. Friction generates heat, converting red phosphorus to white phosphorus. White phosphorus has a very low ignition temperature. It immediately ignites in air, producing heat and light, thus beginning the process of combustion. The heat produced breaks down the potassium chlorate present in the match head, releasing more oxygen. This oxygen combines with antimony trisulfide which is also in the match head and keeps the flame burning.