Jinghao's blog

Picking on Someone Your Own Size

I guess it's customary to pick a fight with a significantly-larger neighbor and then ask for band-aids (or money to pay for damaged war provisions). So explain to me why we are spending so much money to reward Georgia for its brazen provocations, further alienate a necessary world partner Russia, and put us further into debt, just as we forecast the world's largest public budget deficit. Huh?

(Just for reference, one billion dollars can feed 10 million children in Africa for a year)

Silly Investors

The dividend ex-date for FRO is today, meaning you must have bought the stock before today in order to get the dividend, which is three dollars per share.

The stock fell six dollars per share. I hope people are having fun with the three dollar per share loss.

The Speed of Gravity

We'd like to consider physical phenomenons like electromagnetic waves (light, UV, etc) to be instant, because in our approximated world they are. But through an elementary physics education, we learn that they are not. They take time to travel. Magnetic force should also propagate at the same speed because electric fields and magnetic fields do.

So what about gravity? Shouldn't it act in a way that's similar to magnetic and electric forces? What I mean is, does gravity travel instantaneously or at a specific speed? If the latter, is the speed our beloved universal constant--c?

Scenario One

Specifically, consider the following definitions, assumptions and simplifications:

  • The Sun and the Earth are single points in space, an assumption often made in physics to simply calculations
  • r is the distance between the center of the Sun and the center of the Earth
  • M is the mass of the Sun and m is the mass of the Earth at time t0
  • The Sun burns mass at a nearly-constant rate k kg/s (such that k > 0)
  • It takes t seconds for light to travel from the Sun (the "center", in this simplified model) to the Earth.
  • G is the gravitational constant

The question is: at time t0 is the magnitude of the force between the Sun and the Earth F0=GMm/r2, or F1=G(M+t*k)m/r2 (where F1 > F0)? That is, does the Earth feel the effect of the gravity from the Sun before the burning of t*k kg of mass, or the gravity at the exact point in time during which it is measured (from Earth)?

Scenario Two

If you don't like that more-rigorous physical approach, consider this: The Sun suddenly disappears from the center of our solar system. Does the Earth fly off immediately (without the gravity of the Sun to pull it in), or does it do so t seconds later?

What Do I Think?

I would like to think that gravity also propagates as electromagnetic waves do, but I have no convincing reasons why it should. Any inputs? Anyone taking theoretical physics? Astronomy? Anything that would give you the expertise to enlighten me on this? Any constructive input would be greatly appreciated.

Disclaimer

Perhaps this question touches relativistic topics which may provide us with a more definite answer. but I am not in the position to take that into consideration. If anyone has something to add, please do so.

Roomba, Scooba, ... Tomba?

How about a Roomba for tombs? (it says Toomba on the page)

Seniors on-the-Move

Professor Robinson, in his lecture about marketing, mentioned one very specialized moving company, which calls itself "Seniors on-the-Move" and (as you may have guessed) specializes in helping seniors move. They even hang their pictures up for them!

So let's go one step further: Seniors on-the-Internet. Seniors call a 1-800 number, type in their "pin", and tell the operator what website to go to. Then the operator reads the content of the page to the callers.

The callers can even get their emails read to them! Imagine that! Calling a 1-800 number to hear your emails read to you!

I'm just kidding, but this thought made me laugh.

Addicted to Internet Purchases

I just bought a portable 120 GB external hard drive for 30 bucks after tax. Curse me and my unintentionally remembering my credit card numbers! It feels too easy.

I admit though, this was a good deal.

Bribing Regulators

United States had decided to end punitive duties imposed on Hynix Semiconductors, a South Korean company, in 2003, possibly with the intention of winning the favors of South Korean regulators who are considering the monopolistic practices of Intel Corporation, America's very own semiconductor company. I wonder if anyone else thinks that is a reason for their reversal.

Mikhail Gorbachev Comments on Russia...I mean Georgia's War

I thought he was dead, but I guess not.

Olympic Medal Counts

What is an Olympic gold worth to you? Specifically, how many bronze or silver medals would you give up for a single gold? I made this script which downloads data from Wikipedia and calculates the equivalent gold medals. Now people can stop complaining about how China ranks countries by number of gold medals and the United States ranks countries by total medals.

Notes: (1) the cache is updated hourly, so this may not reflect the most recent competitions; (2) the default values are based on relative densities of the three metals. Enjoy.

and if one gold medal equals either of the following:
  • bronze medals
  • silver medals
Raw data and equivalents in gold:
  • CHN has 51 gold medals, 21 silver medals and 28 bronze medals, the equivalent of 74 gold medals.
  • USA has 36 gold medals, 38 silver medals and 36 bronze medals, the equivalent of 72 gold medals.

Therefore, the winner between the two is CHN

I'm Sorry/I Apologize

My professor was going over the nuances of "bad news" wording, and he explained the nuances between being sorry, apologizing, and regretting something:

He asked us to compare the following:

  1. I'm sorry that your grandmother died: Correct
  2. I apologize that your grandmother died: Not really, unless you killed her and feel bad about it
  3. I regret that your grandmother died: Not unless you actually knew her

The second one made me laugh.

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