The visible universe—including Earth, the sun, other stars, and galaxies—is made of protons, neutrons, and electrons bundled together into atoms. Perhaps one of the most surprising discoveries of the 20th century was that this ordinary, or baryonic, matter makes up less than 5 percent of the mass of the universe.
The rest of the universe appears to be made of a mysterious, invisible substance called dark matter (25 percent) and a force that repels gravity known as dark energy (70 percent).
Scientists have not yet observed dark matter directly. It doesn't interact with baryonic matter and it's completely invisible to light and other forms of electromagnetic radiation, making dark matter impossible to detect with current instruments. But scientists are confident it exists because of the gravitational effects it appears to have on galaxies and galaxy clusters.
For instance, according to standard physics, stars at the edges of a spinning, spiral galaxy should travel much slower than those near the galactic center, where a galaxy's visible matter is concentrated. But observations show that stars orbit at more or less the same speed regardless of where they are in the galactic disk. This puzzling result makes sense if one assumes that the boundary stars are feeling the gravitational effects of an unseen mass—dark matter—in a halo around the galaxy.
Dark matter could also explain certain optical illusions that astronomers see in the deep universe. For example, pictures of galaxies that include strange rings and arcs of light could be explained if the light from even more distant galaxies is being distorted and magnified by massive, invisible clouds of dark matter in the foreground-a phenomenon known as gravitational lensing.
Scientists have a few ideas for what dark matter might be. One leading hypothesis is that dark matter consists of exotic particles that don't interact with normal matter or light but that still exert a gravitational pull. Several scientific groups, including one at CERN's Large Hadron Collider, are currently working to generate dark matter particles for study in the lab.
Other scientists think the effects of dark matter could be explained by fundamentally modifying our theories of gravity. According to such ideas, there are multiple forms of gravity, and the large-scale gravity governing galaxies differs from the gravity to which we are accustomed.
Dark energy is even more mysterious, and its discovery in the 1990s was a complete shock to scientists. Previously, physicists had assumed that the attractive force of gravity would slow down the expansion of the universe over time. But when two independent teams tried to measure the rate of deceleration, they found that the expansion was actually speeding up. One scientist likened the finding to throwing a set of keys up in the air expecting them to fall back down-only to see them fly straight up toward the ceiling.
Scientists now think that the accelerated expansion of the universe is driven by a kind of repulsive force generated by quantum fluctuations in otherwise "empty" space. What's more, the force seems to be growing stronger as the universe expands. For lack of a better name, scientists call this mysterious force dark energy.
Unlike for dark matter, scientists have no plausible explanation for dark energy. According to one idea, dark energy is a fifth and previously unknown type of fundamental force called quintessence, which fills the universe like a fluid.
Many scientists have also pointed out that the known properties of dark energy are consistent with a cosmological constant, a mathematical Band-Aid that Albert Einstein added to his theory of general relativity to make his equations fit with the notion of a static universe. According to Einstein, the constant would be a repulsive force that counteracts gravity, keeping the universe from collapsing in on itself. Einstein later discarded the idea when astronomical observations revealed that the universe was expanding, calling the cosmological constant his "biggest blunder."
Now that we see the expansion of the universe is accelerating, adding in dark energy as a cosmological constant could neatly explain how space-time is being stretched apart. But that explanation still leaves scientists clueless as to why the strange force exists in the first place.How to make funnel cakes? how to improve muscular endurance travel advice panama how cell phone long distance calling receiving good advice when your opponent has a good argument word search paper what is the difference between gravy and sauce how to improve eye contact in baby What red roses mean? How to run faster? How to measure square footage of a room? what is touch typing skills How to make puppets? what is the definition of the muscular system what is the definition of stem suprarenal How to use a cane? What does form mean in art? What does ibm mean? how to qualify for va disability benefits how much practice time should hockey coaches spend on fundamental skills What does badges mean on iphone? What time of day does irs deposit refunds 2022? What is the meaning of imprisonment? Cast down your bucket where you are meaning? how to make a personal computer helper on screen what are the metacognitive skills Tips for teachers when dealing with angry parents? what is the definition of wealthy What are the 4 types of parenting styles? What does progressive mean in politics? who is the helper in the turkish ataturk fight with greeks emp admin helper how to add mods What does investing mean? What disease does bruce willis have? How to make a anime club in high school tips and tricks? What time does ufc 269 start? what is the difference between yams and sweet potatoes what does employee benefits mean which behavioral skills training component functions as the behavioral aspect what are the benefits of hawaiian spirulina what skills do you need to be a petroleum engineer how long does it take for your credit to improve after travel hacking What does cashback mean for credit cards? What does send read receipts mean? How long to blanch green beans? which of the following is a part of the definition of heterophony? What time does kissing booth 3 come out on netflix? what is the definition of x intercept what is management skills definition how to improve child health what card games are most effecctive for improving math skills How old should a puppy be to train tricks? who qualifies for native american higher education benefits What does kaylee mean? What does conservative mean in politics? what is sales target definition What does x mean in roman numerals? How long does it take to get abs? What is the meaning of disorder? What does the word benevolent mean? What is huggy wuggy? which of the following does the confidence level measure? How to factory reset phone? What does rendering mean? what are the benefits of a professional instagram account How long to microwave a sweet potato? what is the difference between size 18 and 18w What is the meaning of raya? What does earwax do? How long to broil turkey tips? Tips on how to wear a palazzo with kurta? wisdom is found in those who take advice how much water in hamburger helper cheeseburger macaroni what are the benefits of titanium What is the meaning of profundity? What is a lien on a house? What does remittance mean? How to make moon in little alchemy 2? how to improve measurement accuracy What does objection mean in court? What does font mean? how to tell the difference between silver and silver plated what is the difference between single bevel and double bevel miter saw What is the meaning of empathy in english? what is the definition of locomotor skills what is definition what is retail therapy definition What is a yugioh divine tips? advice for plot- man turns giant (l) what should i do about clothes? How to make a widget? how to improve visual motor integration skills who definition of reproductive health What is the spiritual meaning of grace? What is the meaning of the affix "-ceas"? what are the benefits of brain breaks how to improve my customer service skills How to cancel walmart order? how to improve poshmark sales how to fix application package helper in kindle fire How to cuddle? How to do coin magic tricks? what is the difference between toyota highlander limited and platinum how to improve grip for deadlift how to improve your school essay How to season shrimp? What is the meaning of lonesome dove? Tips on how to invest your money? what is radical feminism definition how to improve communications writing advice for when you don't want writing advice What are beauty marks? How to stop breast milk? what benefits do weighted blankets have How to use apple watch series 3 tips? What time does book of boba fett come out? What does s&m mean? what is the foundation needed for gross motor skills to develop? where were definition what can you do to improve thinning skin What does contrast mean?
Who discovered dark matter?
Dark matter wasn't "discovered" by any one person or group. In fact it is still hypothetical and there is no solid proof for its existence. Various astronomers inferred the existence of dark matter from what they observed about galaxies and galaxy clusters. It is still very much a mystery and the subject of some serious research.