What Is gamma?
Gamma is an old scientific unit used to describe the strength of a magnetic field. Today scientists almost always use the unit nanotesla instead, and one gamma is equal to one nanotesla.
Definition
Gamma is a unit of magnetic flux density. This tells us how strong and how concentrated a magnetic field is in a certain area.
In modern terms:
- 1 gamma = 1 nanotesla
- 1 gamma = 0.000000001 tesla
So gamma is a very small unit. It is useful for measuring weak magnetic fields like the magnetic field of Earth.
History / Origin
Gamma comes from the old cgs system of units that many scientists used before the international system SI became standard. In that older system, magnetic fields were often measured in gauss. For very small fields, scientists needed a smaller step in size, so they used gamma.
The name gamma comes from the Greek letter gamma, written as γ, which was used as the symbol for this unit. The unit was used a lot in geophysics and space science to describe changes in Earths magnetic field.
When the tesla became the official SI unit for magnetic flux density around the middle of the 1900s, gamma slowly became less common in official work. Scientists then replaced gamma with nanotesla, which has exactly the same size.
Symbol & Abbreviation
Gamma uses the Greek letter gamma as its symbol:
- Full name: gamma
- Symbol: γ
- Relationship: 1 γ = 1 nT
In older papers you might see the symbol written as a normal g or as the word gamma, especially when the Greek letter was not easy to print.
It is important not to confuse this unit with other uses of the word gamma, such as gamma rays in physics or gamma correction in images.
Current Use Around the World
Officially, most countries and scientists use SI units. That means they use tesla and nanotesla instead of gamma. Modern textbooks, standards, and most research papers talk about nanotesla rather than gamma.
However, the word gamma still appears in:
- Older scientific books and papers about magnetism or geophysics
- Historical data sets on Earths magnetic field
- Some speech or habit among long time researchers who learned the term years ago
In practice, when someone talks about gamma for magnetic field strength, they almost always mean the same thing as nanotesla.
Example Conversions
These examples show how gamma compares with other units for magnetic flux density.
Between gamma and nanotesla
- 1 gamma = 1 nanotesla (nT)
- 100 gamma = 100 nT
- 50,000 gamma = 50,000 nT
Between gamma and tesla
- 1 gamma = 0.000000001 tesla = 1 × 10−9 tesla
- 1,000,000 gamma = 0.001 tesla
- 1 tesla = 1,000,000,000 gamma
Between gamma and gauss
1 tesla = 10,000 gauss. Using this, we can link gamma and gauss.
- 1 gamma = 0.00001 gauss = 1 × 10−5 gauss
- 100,000 gamma = 1 gauss
- 50,000 gamma = 0.5 gauss
Earths magnetic field in gamma
Near Earths surface, the magnetic field is about:
- 25,000 gamma to 65,000 gamma
- that is 25,000 nT to 65,000 nT
Related Units
Gamma is closely related to these units of magnetic flux density:
- Tesla (T) the main SI unit for magnetic flux density, used for strong fields such as inside MRI machines
- Nanotesla (nT) a billionth of a tesla, the modern unit that exactly matches the old gamma
- Gauss (G) an older cgs unit still seen in some areas like physics and astronomy, 1 G = 100,000 gamma
- Millitesla (mT) 1,000,000,000 gamma = 1 T, so 1 mT = 1,000,000 gamma
All these units describe the same kind of thing, the strength of a magnetic field. They only differ by size and by which system of units they belong to.
FAQs
What does the gamma unit measure?
Gamma measures magnetic flux density, which is a way to talk about how strong a magnetic field is in a certain area.
Is gamma still used today?
Gamma is not an official modern unit. Today scientists use nanotesla instead, but many older papers and some researchers still mention gamma out of habit.
How big is 1 gamma?
One gamma is very small. It is equal to one nanotesla, which is one billionth of a tesla. It is a useful size for measuring Earths magnetic field.
How do I convert gamma to tesla?
To change gamma to tesla, divide by 1,000,000,000. For example, 50,000 gamma is 50,000 divided by 1,000,000,000, which gives 0.00005 tesla.
How do I convert between gamma and nanotesla?
You can treat them as the same. One gamma equals one nanotesla, so the number value does not change.
Is gamma the same as gamma rays?
No. The gamma unit is about magnetic field strength. Gamma rays are a type of high energy electromagnetic radiation. They are completely different concepts.
Why did scientists stop using gamma?
Scientists moved to the SI system to make measurements clear and standard worldwide. In that system, nanotesla replaces gamma and fits better with tesla and other SI units.
