Daily Logs for July 22, 2025

Tags: car

Written by: Tushar Sharma

Dear Vishi, my logs for today.

Engine Oil Change

I ordered synthetic oil from amsoil.com for my Honda Accord 2017. It's better than regular oil.

Product	Package Size	Qty	Price
AMSOIL Signature Series 0W-20 100% Synthetic Motor Oil	Quart Bottle	5	$77.45
AMSOIL Oil Filter	EA15K13	1	$13.30

Most car's autocare shops don't let you bring your own oil or parts. I found a cheap one at Queen City Auto Care & Lube at 6286 South Blvd, Charlotte, NC 28217. It charges only 20 bucks for an oil change. That's the most reasonable I have found. Would recommend.

Things to Do on Long Car Drives

I usually commute long hours to work. I wonder what all things I can do while driving:

Listening to songs
Learn a language
Talk to ChatGPT and ask questions
Watch a movie (not recommended)
Listen to a book or a podcast
Talk to a friend (or family)

Why the Sky is Blue

Today I listened to Why the Sky is Blue by C.V. Raman, a famous Nobel Prize Laureate in Physics from India. He delivered this lecture at the Community Science Center in 1968.

Key insights from the lecture:

1. The Chain of Questions Approach

When someone asks "Why is the sky blue?", don't just give a direct answer. Instead, ask another question: "Is the sky always blue?"

This leads us to realize that the sky only appears blue in daylight. So what's the difference between night and day? The sun.

Next question: But moonlight is practically sunlight reflected, yet there's no bluish color at night. So it depends on illuminance - the color only appears at higher light intensity levels.

Now we know that both atmosphere and sun are responsible for the color, but how? Next question: Does it appear more blue on clear skies or cloudy skies?

This chain of questioning leads to understanding the phenomenon at a much deeper level.

2. Avoid Superficial Answers

Don't give short, casual answers. For example, saying "leaves are green because of chlorophyll" is technically correct but lacks inquisitiveness. The real question becomes: Why does chlorophyll absorb certain wavelengths and reflect green light?

3. Light Scattering and Particle Size

Light is scattered most effectively when its wavelength is approximately equal to the size of the scattering particle. Think of it like resonance - a wave is more able to resonate with a piece of wood its own size rather than with a massive ship.

This principle explains why shorter blue wavelengths are scattered more by tiny atmospheric particles than longer red wavelengths.

The key insight: More blue light is scattered in the atmosphere due to microscopic particles and gas molecules. Without these scattering particles, there would be no blue sky - just the black void of space visible during the day.

New Concepts

Financial Instrument: A legally binding contract that represents a monetary value and can be traded between parties. These instruments derive their value from underlying assets and generate future cash flows. Examples include:

Equity instruments: Stocks, shares
Debt instruments: Bonds, treasury bills, certificates of deposit
Derivative instruments: Options, futures, swaps

CUSIP (Committee on Uniform Securities Identification Procedures): A 9-character alphanumeric code that serves as a unique identifier for securities issued in the United States and Canada. Think of it as a "fingerprint" or "serial number" for financial instruments. The format consists of:

First 6 characters: Identify the issuer
7th & 8th characters: Identify the specific issue
9th character: Check digit for validation

Booking a Flight for Visa Purposes

I need to buy a refundable flight for visa purposes. In my experience, it's better to book it directly with the airline rather than through a middleman. I booked main refundable from the Delta website.