Scientists have been working to obtain this measure, also known as extragalactic background light (EBL) or “cosmic fog,” for a long time. “The EBL represents the book reporting the story of stellar activity and galaxy evolution within the universe,” Marco Ajello, lead researcher and astrophysicist at Clemson College of Science in South Carolina, said in an email.
Measuring EBL could be a great tool for scientists, helping them to better understand galaxy evolution, stellar formation processes, and how the universe has evolved, Ajello explained. But, until now, scientists haven’t been able to make this measurement because EBL is much dimmer than the Milky Way and other light in the night sky. Scientists were not able to observe far away galaxies because they were too dim and brighter light in the foreground further obscured this view. Now, by using an indirect method, scientists have finally made this measurement. The team found that the amount of starlight, or the number of photons (particles of visible light) that stars have emitted throughout the history of the observable universe is 4×10^84 photons. Or, alternatively, 4,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000 photons. An Indirect Measurement The team was able to make this stellar measurement by observing blazars, or galaxies with supermassive black holes emitting beams of matter and radiation in our direction, using NASA’s Fermi Gamma-ray Space Telescope. “By using blazars at different distances from us, we measured the total starlight at different time periods. We measured the total starlight of each epoch — one billion years ago, two billion years ago, six billion years ago, etc. — all the way back to when stars were first formed. This allowed us to reconstruct the EBL and determine the star-formation history of the universe in a more effective manner than had been achieved before,” Vaidehi Paliya, a co-author and postdoctoral fellow who analyzed almost nine years of relevant data, said in a statement. Blazars emit jets of energetic particles which include gamma-rays, or ultra-energetic photons. And gamma rays emitted from blazars travel through the cosmic fog (EBL), which is made up of visible and ultraviolet starlight. When gamma rays collide with visible light, they turn into pairs of electrons and positrons. “In effect, the process dampens the gamma ray signal in much the same way as fog dims a distant lighthouse,” NASA stated in a press release about the phenomenon. These collisions leave visible imprints that scientists can observe using Fermi. “By measuring how many photons have been absorbed, we were able to measure how thick the fog was and also measure, as a function of time, how much light there was in the entire range of wavelengths,” Ajello said in the statement. By mapping the varying densities of this cosmic fog, the researchers were able to observe extremely far (and therefore, extremely old) starlight because these collisions happen over great distances. This technique also worked because, by indirectly observing the starlight through the interactions between gamma rays and visible light, the technique isn’t obscured or impeded by bright foreground light. “The first billion years of our universe’s history are a very interesting epoch that has not yet been probed by current satellites. Our measurement allows us to peek inside it. Perhaps one day we will find a way to look all the way back to the Big Bang. This is our ultimate goal,” Ajello concluded in the statement. The figure 4 x 10^84 represents the total number of photons produced by stars throughout the observable universe's history, not the number of photons in the universe at any given time. Astrophysicists indirectly measured this by analyzing gamma rays from blazars that interacted with the extragalactic background light (EBL). By observing how much light was absorbed at different distances, they could reconstruct the star-formation history and calculate the total starlight produced. WHEBNEVER ELECTRON ENERGY IS LOWERED AND PROTON ENERGY IN SURPLUS YIELD 0.7 SURPLUS WHICH MICROSMAL, SUCH EXTRA ENERGY WITHOUT MASS IS TERMED AS BIRTH OF PHOTON. SO FAR EMISSIONS ONLY WERE 4* 10^84 AND NOT ALL PHOTONS TRAVELLING ALL OVER WHICH IS UNKNOWN SINCE PHOTONS DO NOT DIE EVEN IF IT IS NOT A MATTER. AND ABSENCE OF PHOTONS LOCATION ALONE CAUSE THE DARKNESS. HENCE IT IS NOT STAR, MOON, SUN OR TUBE LIGHT AND BULBS THAT EMITS LIGHT PHOTONA, BUT ATOMS AS PARTICLE AND WAVE LENGTH, LEAVES A TWINKLING ENERY DIFFERENCE AS PHOTON WHICH ALONE LIGHTS ALL PARTS. HOWEVER, EVEN IF PHOTONS ARE NOT DEAD, AND TRAVELLING , STILL THE PASSED -PHOTONS DO NOT COMEBACK AGAIN TO LIGHT AND THEREFORE, ALL THE TOOLS THAT ARE THE CAUSE OF LIGHT ARE ESSENTIAL THROUGH WHICH ONLY PHOTON IS BORN AND GLOWS IN THAT MOMENTUM AND MOVEMENTS. YET ENERGY OF PHOTON AS FORMULATED “HV” IS AN ABSOLUTE MEASUREMENT AS PHOTON PARTICLE ONE EVEN IF NOTICED BY OUR EYES, THE OTHER ONE WILL BE MISSING. THUS, PHOTON ENERGY IS ALSO NOT EXACTLY MEASURABLE. AS NUMBER OF PHOTONS AVAILABITY. Yes, till date whether atom or energy from atom photon, exactitude is unknown which singularity theory was a failure as admitted by late Hawking. K RAJARAM IRS 17925 On Wed, 17 Sept 2025 at 09:01, Markendeya Yeddanapudi < [email protected]> wrote: > > > -- > *Mar*Great question. Let's dive into it clearly and thoroughly: > ------------------------------ > 🔆 *How Are Photons Formed?* > > Photons are *created whenever charged particles accelerate or transition > between energy states*. They're not made of smaller parts — photons are > *elementary > particles*, and they’re the *quantum of light* and all other > electromagnetic radiation. > 🧪 *Common Ways Photons Are Formed:* > ------------------------------ > 🔹 1. *Electron Transitions in Atoms* (most common in everyday light) > > - > > When an electron in an atom *drops from a higher energy level to a > lower one*, it *releases energy* in the form of a *photon*. > > Example: > > Hydrogen atom: > Electron falls from n = 2 to n = 1 → emits photon (Lyman-alpha line) > > > - > > The photon's *energy* = difference between the two energy levels: > > where is Planck’s constant, and is the frequency. > > ------------------------------ > 🔹 2. *Charged Particles Accelerating* > > Any time a *charged particle* (like an electron) is *accelerated*, it > emits radiation — i.e., *photons*. > Examples: > > - > > *Radio antennas*: Accelerating electrons in the antenna produce *radio > waves* (low-energy photons). > - > > *Synchrotron radiation*: Electrons moving near the speed of light in > magnetic fields emit *high-energy photons*. > > ------------------------------ > 🔹 3. *Matter-Antimatter Annihilation* > > When a *particle* meets its *antiparticle*, they annihilate and create > *photons*. > Example: > > (Electron + Positron → Two gamma-ray photons) > > This is pure mass-energy conversion into photons via Einstein’s equation . > ------------------------------ > 🔹 4. *Blackbody Radiation (Thermal Emission)* > > Any object with temperature > 0 K emits photons. > > - > > Hotter objects emit *higher-energy* photons. > - > > A red-hot stove emits *infrared and visible light* photons. > - > > The Sun emits *a broad spectrum* of photons from visible to > ultraviolet. > > This is due to the *random motion and acceleration of charged particles* > (mostly electrons) inside the material. > ------------------------------ > 🔹 5. *Nuclear Reactions* > > In nuclear processes (like *fission*, *fusion*, or *radioactive decay*), > *gamma-ray > photons* are often emitted. > Example: > > - > > After a nucleus decays into a lower-energy state, it emits a *gamma > photon* to shed excess energy. > > ------------------------------ > 🔹 6. *Quantum Field Fluctuations* > > In *quantum field theory (QFT)*, photons are *excitations of the > electromagnetic field*. They’re created when a system interacts in a way > that *perturbs the EM field*, causing a *quantized excitation* — a photon. > > This is the *most fundamental* explanation, though more abstract than > classical pictures. > ------------------------------ > 🧭 So... Where do they come from, really? > > Photons *aren’t built from anything smaller*. They: > > - > > *Emerge* from processes that involve *changes in energy of charged > systems* > - > > Are *conserved carriers* of energy, momentum, and angular momentum > > They’re the *"messengers"* or *"quanta"* of the electromagnetic force. > ------------------------------ > 🧠 Related Thought (to your earlier question): > > If you're thinking of photons as *“effort packets”* — then when a system > (like an atom or a particle) needs to *give off energy*, it "packages" > that effort into a photon, which then travels at the speed of light. > > So in a poetic sense: > > Photons are the universe’s way of *exporting effort* (energy change) > across space and time. > > ------------------------------ > > If you'd like, I can also explain how photons are absorbed, or how quantum > electrodynamics (QED) models all of this. > > -- > You received this message because you are subscribed to the Google Groups > "Thatha_Patty" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion visit > https://groups.google.com/d/msgid/thatha_patty/CACDCHCJpSqBK6fS_DGUDFidooe%3Dw-hOHgOW9v30SvSsAZt%3D8uA%40mail.gmail.com > <https://groups.google.com/d/msgid/thatha_patty/CACDCHCJpSqBK6fS_DGUDFidooe%3Dw-hOHgOW9v30SvSsAZt%3D8uA%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "Thatha_Patty" group. 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