the big bang
Are photons immortal?
A photon is immortal if it does not meet some matter on its way, or even another photon. If it meets a particle, it will interact with some probability given by quantum mechanical calculations. In that sense it is not immortal, because in interacting it may be completely absorbed into new particles.
Answer 4: Ordinarily, no, light will continue on its path forever unless it runs into something. Now, this said, very powerful photons (i.e. gamma rays) can spontaneously transform into particle-antiparticle pairs.
Can photons be destroyed?
Photons are easily created and destroyed. The movement of electrons is responsible for both the creation and destruction of the photons, and that’s the case for a lot of light production and absorption.
Photons could conceivably decay, but new analysis of the cosmic microwave background shows that a visible wavelength photon is stable for at least 1018 years.
What if photons didn’t exist?
If photons didn’t exist then, probably we would all die out due to the fact that photons carry our source of light and UV radiation. So if they weren’t around then all the plants would die out due too a lack of energy for photosinthesis, so, they would not grow and die out. We would also die out due to lack of UV.
Are photons infinite?
Even though photons are waves, they have energy and from general relativity you can only have so much energy in a certain region up to a point where the energy density is so high that the region will collapse into a black hole. At this point the region will be infinitely dense and infinitely small.
Do photons follow Geodesics?
The most commonly accepted view is that gravity bends spacetime, and the curvature itself is the deformation of spacetime itself. All known particles (not just photons) follow this geodesic.
Is light always moving?
Light, no matter how high-or-low in energy, always moves at the speed of light, so long as it’s traveling through the vacuum of empty space. Nothing you do to your own motion or to the light’s motion will change that speed.
Do photons dissipate?
In contrast, light waves can travel through a vacuum, and do not require a medium. In empty space, the wave does not dissipate (grow smaller) no matter how far it travels, because the wave is not interacting with anything else.
Is light a form of energy?
In fact visible ‘light’ is a form of radiation, which can be defined as an energy that travels in the form of electromagnetic waves. It can also be described as a flow of particle-like ‘wave-packets’, called photons, that travel constantly at the speed of light (about 300 000 kilometres per second).
Can two photons collide?
However, two photons heading towards each other can indeed collide indirectly. The process goes like this. A photon can spontaneously degenerate into a particle with mass and its antiparticle in a process known as pair production.
Where do photons end up?
A photon can interact with charged particles and give up part of its energy or even all of it, and then it “disappears”.
Can you have light without photons?
The answer is then definitely “no”: the photon is a massless particle.
How old is the oldest photon?
It is 13.77 billion years old, give or take 40 million years.
Can a photon exist at rest?
A photon always travels at the speed of light in a vacuum. It’s never at rest.
What happens if you touch antimatter?
Our bodies also contain potassium-40, which means positrons are being emitted from you, too. Antimatter annihilates immediately on contact with matter, so these antimatter particles are very short-lived.
Has antimatter been proven?
For the past 50 years and more, laboratories like CERN have routinely produced antiparticles, and in 1995 CERN became the first laboratory to create anti-atoms artificially. But no one has ever produced antimatter without also obtaining the corresponding matter particles.
Is there antimatter on Earth?
The Big Bang should have created equal amounts of matter and antimatter in the early universe. But today, everything we see from the smallest life forms on Earth to the largest stellar objects is made almost entirely of matter. Comparatively, there is not much antimatter to be found.
How long does a photon last?
But if they do have a little mass, they could eventually decay into lighter particles. Now, by studying ancient light radiated shortly after the big bang, a physicist has calculated the minimum lifetime of photons, showing that they must live for at least one billion billion years, if not forever.
Is light everywhere at once?
Yet despite this incredible journey, the photon itself experiences none of what we know as time: it simply is emitted and then instantaneously is absorbed, experiencing the entirety of its travels through space in literally no time. Given everything that we know, a photon never ages in any way at all.
Do photons bend space time?
Yes, photons bend spacetime.
What is geodesic in physics?
In general relativity, a geodesic generalizes the notion of a “straight line” to curved spacetime. Importantly, the world line of a particle free from all external, non-gravitational forces is a particular type of geodesic. In other words, a freely moving or falling particle always moves along a geodesic.
How do you use geodesic equations?
What is the speed of light in seconds?
The speed of light traveling through a vacuum is exactly 299,792,458 meters (983,571,056 feet) per second. That’s about 186,282 miles per second ” a universal constant known in equations as “c,” or light speed.
How did Einstein find the speed of light?
It can be derived from Maxwell’s equations that the speed at which electromagnetic waves travel is: c=(ϵ0μ0)’1/2. Since light is an electromagnetic wave, that means that the speed of light is equal to the speed of the electromagnetic waves.
How fast is the speed of dark?
Darkness travels at the speed of light. More accurately, darkness does not exist by itself as a unique physical entity, but is simply the absence of light. Any time you block out most of the light ” for instance, by cupping your hands together ” you get darkness.
How fast is a light-year in mph?
In a vacuum, light travels at 670,616,629 mph (1,079,252,849 km/h). To find the distance of a light-year, you multiply this speed by the number of hours in a year (8,766). The result: One light-year equals 5,878,625,370,000 miles (9.5 trillion km).
Does light travel forever?
Light is an electromagnetic wave that doesn’t need a medium to propagate. The strength of the wave, however, can get weaker with the distance, but as long as nothing absorbs it, the light keeps on travelling forever.
Does light travel through air?
So how does light travel? Basically, traveling at incredible speeds (299 792 458 m/s) and at different wavelengths, depending on its energy. It also behaves as both a wave and a particle, able to propagate through mediums (like air and water) as well as space.
How far can light travel before it dissipates?
Light dissipating In fact there is no known limit to how far light can travel. However, as you will be aware from observing torch beams or car headlights, there is a limit to the distance over which these are effective sources of illumination. There are two reasons for this.
What is light Byjus?
Answer: Light is an electromagnetic wave emitted by hot objects like lasers, bulbs, and the sun. Light is a type of kinetic energy that allows us to see or make objects visible with our eyes. The human eye can see light energy, which is a type of electromagnetic radiation.
How was light created?
Light is made up of photons, which are like tiny packets of energy. When an object’s atoms heat up, photon are produced from the movement of atoms. The hotter the object, the more photons are produced.
What is the bouncing of light called?
Reflection is when light bounces off an object. If the surface is smooth and shiny, like glass, water or polished metal, the light will reflect at the same angle as it hit the surface. This is called specular reflection.
Does light interact with light?
Classically, light cannot interact with light because photons ” even though they mediate interactions between charged particles ” do not themselves carry charge.
Can light reflect off of light?
When surface imperfections are smaller than the wavelength of the incident light (as in the case of a mirror), virtually all of the light is reflected equally. However, in the real world most objects have convoluted surfaces that exhibit a diffuse reflection, with the incident light being reflected in all directions.
Do photons come from the sun?
The sunlight is made up of tiny “packets of light” called photons, that originate in the Sun’s core. The photons are born in a nuclear fusion, when hydrogen cores smash together to make helium. As a byproduct of this reaction, a huge amount of energy is released in the form of photons.
What if photons have mass?
If photons have mass, then obviously the “speed of light” becomes a misnomer. Massless particles would still travel at that speed ” if any particles end up being massless after the carnage is done.
Can you hold a photon?
Single photons are ideally suited for sending information in digital form so that each photon encodes a 0 or a 1. In that case, it’s easy to imagine that this is all the data that a single photon can hold. Not so! In theory, there is no limit to the amount of information a single photon can encode.
Are photons attracted to anything?
Photons do not have mass or charge, which is why they have little to no effect on each other as they cross paths; they neither attract nor repel one another.
Why is Hubble time the age of the universe?
The inverse of the Hubble Constant is the Hubble Time, tH = d/v = 1/Ho; it reflects the time since a linear cosmic expansion has begun (extrapolating a linear Hubble Law back to time t = 0); it is thus related to the age of the Universe from the Big-Bang to today.
What is the oldest thing in the universe?
Microscopic grains of dead stars are the oldest known material on the planet ” older than the moon, Earth and the solar system itself. By examining chemical clues in a meteorite’s mineral dust, researchers have determined the most ancient grains are 7 billion years old ” about half as old as the universe.
Do we really know how old the universe is?
We do not know the exact age of the universe, but we believe that it is around 13 billion years ” give or take a few billion. Astronomers estimate the age of the universe in two ways: (a) by looking for the oldest stars; and (b) by measuring the rate of expansion of the universe and extrapolating back to the Big Bang.
What is the weight of a photon?
According to electromagnetic theory, the rest mass of photon in free space is zero and also photon has non-zero rest mass, as well as wavelength-dependent. The very recent experiment revealed its non-zero value as 10 ” 54 kg ( 5.610 × 10 ” 25 MeV c ” 2 ) .
Does a photon have momentum?
Measuring Photon Momentum Particles carry momentum as well as energy. Despite photons having no mass, there has long been evidence that EM radiation carries momentum. (Maxwell and others who studied EM waves predicted that they would carry momentum.) It is now a well-established fact that photons do have momentum.
Do all photons have same mass?
Since frequency (v) of different colours is different, hence their equivalent masses are different.