In my day, I was pretty much a math whiz and still pride myself on those skills today.  But, when my 17-year-old, high school, distinguished honor student in his senior year, was having problems with his summer AP Calculus packet that was due on the first day of school, there wasn’t a darn thing I could do to help solve any parts of the problems on the page…except let my mom instincts kick in and find him someone who could.

I said, “Let’s log on to Tutor.com.”  And after a series of protests, like “They won’t be able to help with these kind of problems; They might not be ‘real’ teachers; and Nah, I don’t feel like it, I’ll do it later,” I did what any all-knowing mom would do.  I countered with:  They are all qualified teachers, professors, graduate students, etc.; they have experts in every academic topic from kindergarten to twelfth grade and even help college students; and it’s available whenever you need help 24/7. Now move over so I can get you a password.”

Reluctantly he got out of my way, and in less than a minute, we were logged on.

Skeptical, yet curious, he sat down at the chair and began communicating with the tutor. Before I knew it he was writing the problem on the interactive whiteboard and the tutor was asking him questions to assess where to start.  Within minutes they were chatting like old friends, solved the first problem and went on to the next.

I discreetly backed out of the room and let them handle their business while I went on to handle mine.  On my face was a big ‘ole smile, in my heart was the pride of helping my ‘baby,’ and in my head was a little voice saying: whew, thank God for Tutor.com.

And now, when he gets together with his AP study group and they get stuck, he signs on and connects to a tutor to help them with the work.

Kudos to Tutor.com for helping moms across the world remain academically confident in the fact that we don’t have to have all the answers, we just need to know where to find help with them!  And Tutor.com is that place.

Pamela McBride is a proud mom, military wife,  career & life coach, author, and freelance writer.  Connect with her at The Work – Life Diva blog (http://pamelamcbride.wordpress.com), on Twitter (@PamelaMMcBride), on Facebook fan pages (Work It, Girl and WorkingItMilitaryLifeStyle) or at www.pamelamcbride.net.

Here’s an excerpt from yesterday’s article:

His low-tech, conversational tutorials — Khan’s face never appears, and viewers see only his unadorned step-by-step doodles and diagrams on an electronic blackboard — are more than merely another example of viral media distributed at negligible cost to the universe. Khan Academy holds the promise of a virtual school: an educational transformation that de-emphasizes classrooms, campus and administrative infrastructure, and even brand-name instructors.

Of course, if your school or local public library offers the Tutor.com Learning Suite, you may already be familiar with Sal Khan.  His videos are some of the most popular and highly-rated educational resources in our SkillsCenter Resource Library, where Tutor.com users have viewed them thousands of times.  You can also find Khan Academy videos free of charge at our website if the Learning Suite isn’t available in your area.

To get you started, here are some of our users’ favorites:

• Quadratic Formula (proof)
• Introduction to Magnetism
• Statistics: Binomial Distribution
• Sex-Linked Traits
• Introduction to Limits

On-demand, online tutoring helps homework questions from becoming learning problems

It’s always easier to take care of a problem while it’s still small. A simple misunderstanding about a question on tonight’s algebra homework can quickly turn into a major math problem. If you get help early on and in the moment you need it, you can avoid a bigger problem, which may require expensive and intensive tutoring and remedial classes to solve.

Online tutoring saves time as well as money

With private tutors reaching into the hundreds of dollars per hour, online tutoring is affordable and be easily worked into your monthly budget.

When you connect to a tutor online, you save money on travel and gas, too. It means no driving to appointments, shuttling multiple students to multiple appointments, or dropping off the tutor at home. You save money not only on travel, but also free up time in your often busy schedule.

Online tutoring means greater access and flexibility

In-person tutoring can be a hassle. You first have to find someone in your neighborhood, qualify that they are reliable and safe and that they can help you with your subject. Sometimes you need help with on more than one subject. Chances are, your physics tutor can’t help you with your social studies research.

Online tutoring solves that problem.   Whether you connect to an expert who can help with your physics homework, or a teacher who can edit your essay, being able to connect online means you don’t have to limit the talent pool to your neighborhood. And it means you don’t have to let strangers into your home, or drive to another appointment. All of Tutor.com’s tutors are already screened and qualified subject experts.

The other great part? Online tutoring is available day and night. You don’t have to make an appointment, worry about changing your schedule or last minute cancellations.

Online tutoring can even be free

Tutor.com works with public agencies to make online tutoring free for millions of students. We have six state-wide programs (including our newest library program in Louisiana) and thousands of public libraries that offer our service for free to the students in their community. There is even free tutoring for military families. If you aren’t eligible for one of these free programs, it’s easy to sign up for a Tutor.com subscription. Check with your local library or school to see if you have access!

This is why Dan thinks Tutor.com is a great job for teachers:

I love coming home after a long day with 30 students in my school classroom and signing into Tutor.com! While that may sound like an odd statement to most people, I’m certain fellow teachers might understand. At least for me, the reason I became a teacher was to help children learn. I know I help children learn in my classroom, but I also know for some students I move too fast or too slow. I know for some students the material is too easy or too hard. I work diligently to adjust, but with 30 students I struggle to help everyone equally everyday.

However, when I’m in the Tutor.com classroom, I can focus on one student at a time. I can move faster or slower depending on that one student. The student has my undivided attention. I don’t have to worry about the students on the other side of the room, the principal walking in or a fire alarm going off. It is just me and the student, typing and whiteboarding towards understanding. The student has my attention, I have the student’s attention and I’m helping someone learn.

Dan tutors Essay Writing, Elementary and Mid-level Math and Geometry.

This is why physics and calculus tutor David A. works for Tutor.com. David is a Professor Emeritus of Physics. :

There are three main reasons why I work for Tutor.com.  The first is that I wish to continue growing professionally.  There is no better way to keep abreast of basic concepts in one’s field than by teaching.

What’s more, I feel that I am learning more about determining individual student needs through one-on-one tutoring online than I did in years of classroom work.  While I am  familiar with the concepts and techniques needed to help students with their questions, I frequently get questions which require further thought or study.  This helps me feel that I’m on the cutting edge.

The second reason is that I appreciate a little added income each month.  While salaries paid hourly for tutoring are lower than one might receive for teaching in the classroom or for private tutoring, there are compensating advantages.  For example, you tutor from your own home and computer on your own hours.  There are thousands of students eagerly awaiting your help. And the income from tutoring makes me more comfortable with discretionary expenses related to my hobbies or home repair.

The final reason is that it’s fun. My career was based upon the fact that it’s enjoyable to help others to understand basic concepts of nature.  When students understand a concept that has been fuzzy before, there is usually spontaneous joy.  The gratitude often overflows in the tutor.com online classroom chat space.  It proves once again that learning is fun.”

For more information on becoming a tutor, please visit www.tutor.com/apply

What brought you to Tutor.com?

At the end of the 2008-2009 academic year, I lost my teaching job at a private school and, due to the poor job market for teachers these days, was unable to get a new position for this past academic year.

Elana, one of my friends from college, mentioned to me in conversation at one point that she had just begun tutoring biology at Tutor.com. She strongly encouraged me to look into tutoring with Tutor.com as well, and so I did.

What is the most rewarding part of tutoring?

Although tutoring sessions often inevitably end up being all about the specific physics problems a student would like to work with me on, I personally find it most gratifying when we end up discussing something of a broader nature. For example, I once was working with a student who believed from his/her physics experience so far that physics was pretty much just math. After explaining a few things to him/her over the course of a few minutes, (s)he began to see that while the topics (s)he had studied so far were very mathematical, as (s)he got farther in his/her course, (s)he would see a lot more conceptual development in the material and would start clearly to see the very scientific nature of physics. In a post-session survey comment, (s)he said (s)he appreciated my changing his/her attitude of physics. I think tutoring sessions like that, where students have life-changing experiences, are by far the most gratifying ones of all.

Do you have any funny or touching Tutor.com stories?

I once had a student who typed up a problem for me, then proceeded to draw a diagram on the whiteboard that was totally unrelated to the problem (s)he had typed up. (S)He then explained that the diagram appeared in the middle of the problem’s description and that (s)he was as confused by this as I was! We ended up drawing our own diagram for the written problem and went from there.

What interests do you have outside of Tutor.com?

Outside of Tutor.com, I enjoy foreign travel, movies, and ’80s music.

Applauding New Thinking On Gravity – Adolfo A.

How We Think About Gravity – Dr. Patrick L.

Questioning Gravity – Pablo A.

We’d love to hear what you think!

A new theory on the gravitational force proposed recently by a renowned physicist, Erik Verlinde of the University of Amsterdam,  has caused quite a stir in the physics community and has even caught the attention of the media (see for example the New York Times article). Verlinde’s paper, titled ”On the Origin of Gravity and the Laws of Newton”,  can also be accessed online.

To understand what the fuss is all about, some background is necessary.

As far as we know, there are only four forces in the universe: the gravitational force, the electromagnetic force (which, as its name indicates, accounts for both the electric and the magnetic forces) and two forces that operate only in atomic nuclei, the so-called strong and weak nuclear forces. Gravity is of course the most familiar of the four and was the first one for which an explicit formula was obtained (the universal law of gravitation, worked out by Newton over four hundred years ago).

In  1915, Einstein presented a new  description of gravity that is  more fundamental (and more beautiful) than Newton’s theory. In this theory, called general relativity, the gravitational force arises through the curvature of spacetime.  Objects are not really pulled by a gravitational force as Newton had suggested, they instead simply move through curved spacetime and it is the bending of that spacetime that affects the motion of objects, which is what we  then observe as a gravitational force. To understand this, consider the surface of a trampoline. If we make a baseball roll on this surface, it will move in a straight line. Now imagine that someone stands in the middle of the trampoline. The surface of the trampoline is now bent down by the weight of the person. If we now push a baseball on this surface not directly at the person but in some other direction, the path will not be a straight line but will curve due to the bending of the surface. In fact, if you push the baseball just in the right direction and at the right speed, it could roll around the person and come back to its initial position! If there was no friction, it could keep doing that forever, although in real life friction will cause it to spiral down until it hits the person. In general relativity, any object bends space and time around it, which affects the motion of other objects. For example, you could replace the person standing on the trampoline by the Earth, the baseball by the Moon  and the surface of the trampoline
by space and time and you would get the General Relativity explanation of why the Moon orbits the Earth!

Although Newton had not understood the real nature of the force of gravity, it does not mean that his universal law of gravitation is useless! It is in fact an extremely good approximation to Einstein’s equations and in almost all practical applications Newton’s law of gravity is precise enough. Indeed, it’s Newton’s theory that was used to send men to the Moon. On the other hand, Einstein’s General Relativity  allows the global positioning system (GPS) to be as accurate as it is.

Some strange properties of gravity started to be noticed in the 1970s through the study of black holes. For reasons  we can’t go into in this blog entry, it was proposed that black holes have an entropy, a concept familiar to you if you have learned about thermodynamics.  This came as a surprise. In thermodynamics, entropy is a measure of  the disorder of a system. For example, imagine holding a stack of playing cards with the cards initially ordered (ace to king of hearts, ace to king of diamonds, ace to king of diamonds and ace to king of clubs). This is a state of low entropy because it is well ordered.

Now you shuffle the deck of cards. It is very unlikely (but not impossible!) that after having shuffled for a while, you will get back exactly the same order you started with. It is also very unlikely that all the first 26 cards will be black and the next 26 will be red, which is also a state that has a lot of order. What is much more likely is that the colors and suits will be pretty much completely mixed and there will be no order in the values of the cards (for example it is unlikely that there will be ten consecutive cards with the values 1 to 10, in that order). We then say that the disorder of the playing cards has increased due to the shuffling and therefore the entropy has increased.  If you have done some thermodynamics, you know that entropy in that case is associated to arrangements of atoms and molecules, which therefore play the role of the playing cards in our example.

Then Stephen Hawking discovered that black holes have a temperature and emit radiation.  In other words, black holes have all the properties of a thermodynamical system.  In 1995, Ted Jacobson of the University of Maryland showed that Einstein’s theory of general relativity can be cast in a form that shows that entropy and temperature can be assigned to gravity itself (and not just to black holes)!  But if this is the case, what is the equivalent of the playing cards in the case of gravity? In other words, what are the things that can be shuffled around to measure the entropy? Nobody knows for sure although there are some tentative ideas floating around in two very active areas of theoretical physics, superstring theory and loop quantum gravity (see for example the books Three Roads to Quantum Gravity by Lee Smolin, The Elegant Universe,  and The Fabric of the Cosmos, both by Brian Greene).

We are finally in a position to understand the proposal of Verlinde.  We need one last analogy. Imagine a very fine string resting on a surface and  which is attached to one extremity while the other one is loose. Let’s imagine that you can move and shake the surface on which the string is resting; it’s on the surface of a book, for example. Now you  shake the book violently and look at the result. It is very unlikely that the string will end up being completely straight because that’s a low entropy configuration. It’s much more likely that the
string will be curled to some extent.

Let’s say that the string is plunged into a liquid at some temperature. Then the molecules in the liquid will be hitting the string from all directions in a rather chaotic manner. Now we come to the main point. If you pull the string to its maximum length and then let it go, it is  initially in a state of low entropy. And now you watch what happens. The molecular collisions will tend to make the entropy of the string increase, which means that the string will slowly bend in a random pattern that has a higher entropy. Now imagine that you pull again the string to its maximum length and this time you don’t let it go. You will then feel a force that pulls the string to a state of higher entropy (which corresponds to the string  curled up). This is what is referred to as an ”entropic force”.  And the higher the temperature of the liquid is, the stronger the force will be because the collisions with the molecules of the liquid will be more violent.  Note that the force that you feel on the string is not a force produced by the string itself, it is really due to the collisions from the the molecules with the string. If we do not know about the molecules and the way they interact with the string, we can still write down equations describing the force exerted by the string on our fingers, but the equations we have thus obtained do not describe a real, fundamental force! The actual force at play is  the force between the molecules and the string that plays a role during the collisions.

Verlinde’s proposal is that what we see as the force of gravity is actually an entropic force! It is important to understand that he does not identify what is the equivalent of the molecules in our string example.There must be some microscopic entities associated to gravity that plays that role, but it is definitely not ordinary matter because gravity is felt in empty space! It is something completely new, possibly something that makes up space and time themselves.

In other words, ”atoms” of space and time!  Verlinde does not need, however, to identify these entities precisely in his theory. His basic idea is that, as two masses get closer to one another, the entropy associated to gravity increases (this is the basic idea, he obviously makes it more precise in his work).  So that, as when the string gets pulled to a curled position because it is a state of higher entropy, two masses are pulled toward one another. For example, if you drop a penny from a certain height, the penny has less ”gravitational entropy”  if it is at a lower height, and the tendency of physical systems to increase entropy will pull the penny down, which is we see as a gravitational force!

This is a completely new way to think of gravity. Indeed, in this approach gravity is not a fundamental force of nature, like the force pulling the string to curl up was just a consequence of the collisions with the molecules of the liquid and not a fundamental force (by the way, when Verlinde says in the NY Times article that he does not think that gravity exists, what he means is that he does not think that gravity as a fundamental force exists, not that objects are not attracted to one another!).

In addition, it begs the obvious question: what are the fundamental entities responsible for the  entropy?

As mentioned earlier, nobody knows for sure!

Verlinde’s idea  is still only a proposal and not all physicists think that it is a viable theory.  In addition, there is no way yet to test experimentally if this is correct and it might prove impossible to do so, which would not make it useful as a physical theory. On the other hand, it could represent the first step in a completely new approach to gravity and lead to a more fundamental understanding of nature.

Dr Patrick L. has been with Tutor.com since 2008 and tutors physics. Read more comments on this  New York Times article by other Tutor.com tutors.