1. What is the Speed of Light in MPH?

Definition: The speed of light in a vacuum is a fundamental physical constant important in many areas of physics.

Value: The exact speed of light in miles per hour is 670,616,629 mph.

2. About the Speed of Light

The speed of light is:

Key facts:

• Universal physical constant
• Exact value by definition
• Maximum speed at which all matter and information can travel
• Important in relativity theory (E=mc²)

3. Importance of the Speed of Light

Details: This constant is crucial for physics calculations, astronomy measurements, GPS technology, and understanding the universe.

4. Using This Calculator

Tips: Simply click "Show Speed" to display the exact value of the speed of light in miles per hour.

5. Frequently Asked Questions (FAQ)

Q1: Why is the speed of light important?
A: It's a fundamental constant of nature that appears in many physical laws and limits how fast information can travel.

Q2: Is this the exact value?
A: Yes, since 1983 the meter (and thus the mile) has been defined in terms of the speed of light, making this an exact value.

Q3: Does light always travel at this speed?
A: Only in a vacuum. Light travels slower when passing through materials like water or glass.

Q4: How was this value determined?
A: Through precise measurements of light's speed, now fixed by definition in the SI system of units.

Q5: What's the speed of light in other units?
A: About 299,792 km/s or 983,571,056 feet per second.