# Are There Other Massless Objects Besides Gluons and Photons?

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In summary: The mass, energy, and momentum of a particle are related by ##E^2=(mc^2)^2+(pc)^2##. For a photon we have ##E=pc## so a bit of algebra will quickly show that the mass of a photon is precisely exactly zero.In summary, energy is a property of objects and systems of objects, and it has mass.
Are there any other things/objects in our universe that are massless other than Gluons and Photons? I guess energy is massless, but it's not so much a thing, more-so a property.

I guess energy is massless, but it's not so much a thing, more-so a property.

Indeed, energy is a property of objects and systems of objects, it is not something in and of itself. But it does have mass. Or, rather, arranging a system such that it has more energy than before will mean it has more mass as well.

Mass and energy are equivalent. When you say something is mass-less, it usually means that the rest mass is zero. This applies to photons and gluons and gravitons (if they exist).

Graviton, if it exists at all.

Don't forget Weyl fermions.

What about a shadow, or digital information?

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Those aren't physical objects.

The OP didn't really qualify what a Thing or an Object was. If you want a macro-sized object, it would have to be an object made of massless particles, like a laser beam.

Laser is an acronym for light amplification by stimulated emission of radiation. It is made of photons of a specific wavelength, but photons none the less and it does have mass just as all photons do, however small it is.

Austin Z W said:
but photons none the less and it does have mass just as all photons do, however small it is.

The mass of the beam is non-zero, but the mass of each photon is zero.

Each photon has energy which means it has mass. The mass is usually said to be zero in most cases and equations because it is such a small amount of mass.

Austin Z W said:
Each photon has energy which means it has mass. The mass is usually said to be zero in most cases and equations because it is such a small amount of mass.
That is not correct. The mass, energy, and momentum of a particle are related by ##E^2=(mc^2)^2+(pc)^2##. For a photon we have ##E=pc## so a bit of algebra will quickly show that the mass of a photon is precisely exactly zero.

## 1. What exactly does it mean for something to be "massless"?

Being "massless" means that the substance or object has no measurable mass or weight. This is typically used to describe particles or subatomic particles that have no rest mass, meaning they do not contribute to the total mass of a system.

## 2. Can something truly have no mass?

Yes, according to our current understanding of physics, there are particles that have no mass, such as photons (particles of light) and gluons (particles that hold together atomic nuclei). These particles are considered fundamental and are integral to our understanding of the universe.

## 3. How can something with no mass still have energy?

In physics, energy and mass are considered interchangeable through the famous equation E=mc^2. This means that even though something may have no mass, it can still possess energy through its massless properties, such as its speed or frequency.

## 4. Are there any practical applications for studying massless things?

Yes, the study of massless particles and their properties is crucial for understanding the fundamental laws of the universe and how it functions. This knowledge also has practical applications in fields such as telecommunications and electronics.

## 5. Can we ever create something that is truly massless?

It is currently not possible to create something that is truly massless. However, scientists are constantly working towards new discoveries and advancements in technology that may one day allow us to manipulate and harness the properties of massless particles in a controlled manner.

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