Thursday, February 19, 2009

Episode 24 - What was the first animal?

Ben sent me a great question, actually it was three questions, and it fits in nicely with the fact that it was just the 200th anniversary of the birth of Charles Darwin (happy birthday Chuck!)

Ben wanted to know, what was the first animal, when did it arrive and he wanted to know how it showed up. Excellent questions all.

Well the oldest animal is something called a comb jelly, which looks sort of like a jelly fish (but it is not one). These things showed up about 525 million years ago, give or take. They are the first organisms with nervous systems.

How does evolution work? You know what it is VERY easy to understand, I have heard it said that it is so easy that anyone can misunderstand it. I am not going to go through it right now, heck I want you to listen to episode 24.

Friday, December 19, 2008

Episode 23 - What Was Before the Big Bang, and How Do the Planets Stay in the Sky?

Lilly from New York City sent me this question a few weeks back.  (I am sorry, I have been quite busy, and have not been able to get to your questions everyone, I will, promise!)  She wanted to know what was there before the big bang which started our universe.  Well the answer is probably going to not make you very happy Lilly, but it is the consensus among scientists that there was no "before the big bang".  You see, the big bang was not just the start of space, it was the start of the universe.  One of the properties of the universe is that time goes forward.  So, the big bang was the start of time.  If it is the start of time, there could not be anything before time started.

Lilly also wanted to know how planets stay in the sky.  Well that is a great question, and I remember my daughter asking a question like that when she was about your age.  All objects attract each other, so we (the earth) are attracted to the sun, and the sun is attracted to us.  This mutual attraction keeps us spinning around the sun, and it works the same way for all of the planets.  

I then used the idea of spacetime to explain gravity a bit further.  It turns out space and time are the same thing , and this spacetime can be thought of as a big blanket.

Enjoy episode 23, and thanks Lilly!

Sunday, September 28, 2008

Episode 22 - How do Space Ships Escape the Earth's Gravity and Have We Ever Gone To The Sun?

In this episode I decided to answer three questions at once. Austin from Massachusetts wanted to know how rockets can get away from our gravity. Well it is not done all at once, and it is not done from Earth. Typically space ships get up into orbit about oh 10 000 km up in space. That sounds pretty far, but GPS and communication satellites are about 40 000 km away from our home planet. So, once they get there they start to accelerate (speed up) and until they reach about 7 km/s (that is 25 500 km/h or 15 750 mph, which is pretty fast no matter how you measure it). That is fast enough to win what is really like a tug of war with the Earth's gravity.

Olivia from Washington state wanted to know if space ships had ever been to the Sun. Well of course not manned ships, but there have been a few unmanned ships that have gone. The closest flyby of the Sun was by a ship called Helios 2. She also wanted to know where the Sun came from, how was it created? Well, I touched on this in Episode 18. Basically there was this REALLY big cloud of molecules. Now, even single molecules have gravitational pull, so they started being attracted to on another. After a time (a really long time, about 50 000 000 years) the stuff at the center of this cloud really could be called a star. Oh when did this happen? The Sun is probably about 4.5 billion years old.

I hope you enjoy episode 22.

Friday, August 1, 2008

Episode 21 - How Does Your Brain Make Your Fingers Move?

Jenna (I hope I spelled your name correctly...) wants to know how your brain controls your fingers. This is a really neat question, and because I am a psychologist, I did not have to ask anyone but myself. One of the very neat things about this is that the left half of your brain controls the right side of your body. Oh, and even though it feels like you move as soon as you want to, it takes at least 300 msec before anything actually happens in your fingers. The key to the whol thing is a neurotransmitter called acetylcholine.

I hope you enjoy episode 21, keep the questions coming!

Wednesday, June 18, 2008

Episode 20 - Why does the human brain think so much?

Originally I was going to do a few updates on previous shows for episode 20, then this gem of a question came in about neuroscience and psychology, how could I refuse?  

Nikhil Kumar of Bloomington, IL is a student at Northpoint Elementary School.  Nikhil asked, why does the human brain think so much?  WOW that is a great question.  Well part of the reason when you are very small anyway (before you are born) is that if you don't use brain cells they die.  (It turns out this is a good thing, don't worry) and well there is also a lot of thinking you are doing that you are not aware of.

If you have sent me a question I will get to it soon, I promise!

Wednesday, April 30, 2008

Episode 19 - Why Isn't Greenland a Continent?

Vince B. sent in a great question, why isn't Greenland considered a continent?  Well I am no geographer, but I work with a guy who is, Dr. William Osei of the Algoma University Geography Department.

It turns out that the word continent is a pretty arbitrarily defined thing.  Basically, according to Dr. Osei, it is based pretty much on size and convention.  Greenland is actually quite small by continent standards, it is only 1/14th the size of Africa!

Thanks to Isabelle for the new music.

Monday, March 3, 2008

An Idea For Episode 20

There must be questions that you think, "Well Dave, that was interesting and all of that, but could you tell me more about......"  For example, I know that in episode 17 I mentioned how fish actually have memories, but, well our questioner wants a bit more info.  (Her Dad ran into me at a podcast meetup and even asked me to tell him more.  I refused, because, well, I thought I would save it for the show :-).  So, is there more you want to know about some topic?  Let me know!