How could an explosive Big Bang be the birth of our universe?
Curious Kids is a series for children of all ages. If you have a question you'd like an expert to answer, send it to curiouskidsus@theconversation.com.
How can a Big Bang have been the start of the universe, since intense explosions destroy everything? – Tristan S., age 8, Newark, Delaware
Pretend you're a perfectly flat chess piece in a game of chess on a perfectly flat and humongous chessboard. One day you look around and ask: How did I get here? How did the chessboard get here? How did it all start? You pull out your telescope and begin to explore your universe, the chessboard….
What do you find? Your universe, the chessboard, is getting bigger. And over more time, even bigger! The board is expanding in all directions that you can see. There's nothing that seems to be causing this expansion as far as you can tell – it just seems to be the nature of the chessboard.
But wait a minute. If it's getting bigger, and has been getting bigger and bigger, then that means in the past, it must have been smaller and smaller and smaller. At some time, long, long ago, at the very beginning, it must have been so small that it was infinitely small.
Let's work forward from what happened then. At the beginning of your universe, the chessboard was infinitely tiny and then expanded, growing bigger and bigger until the day that you decided to make some observations about the nature of your chess universe. All the stuff in the universe – the little particles that make up you and everything else – started very close together and then spread farther apart as time went on.
Our universe works exactly the same way. When astronomers like me make observations of distant galaxies, we see that they are all moving apart. It seems our universe started very small and has been expanding ever since. In fact, scientists now know that not only is the universe expanding, but the speed at which it's expanding is increasing. This mysterious effect is caused by something physicists call dark energy, though we know very little else about it.
Astronomers also observe something called the Cosmic Microwave Background Radiation. It's a very low level of energy that exists all throughout space. We know from those measurements that our universe is 13.8 billion years old – way, way older than people, and about three times older than the Earth.
If astronomers look back all the way to the event that started our universe, we call that the Big Bang.
Many people hear the name 'Big Bang' and think about a giant explosion of stuff, like a bomb going off. But the Big Bang wasn't an explosion that destroyed things. It was the beginning of our universe, the start of both space and time. Rather than an explosion, it was a very rapid expansion, the event that started the universe growing bigger and bigger.
This expansion is different than an explosion, which can be caused by things like chemical reactions or large impacts. Explosions result in energy going from one place to another, and usually a lot of it. Instead, during the Big Bang, energy moved along with space as it expanded, moving around wildly but becoming more spread out over time since space was growing over time.
Back in the chessboard universe, the 'Big Bang' would be like the beginning of everything. It's the start of the board getting bigger.
It's important to realize that 'before' the Big Bang, there was no space and there was no time. Coming back to the chessboard analogy, you can count the amount of time on the game clock after the start but there is no game time before the start – the clock wasn't running. And, before the game had started, the chessboard universe hadn't existed and there was no chessboard space either. You have to be careful when you say 'before' in this context because time didn't even exist until the Big Bang.
You also have wrap your mind around the idea that the universe isn't expanding 'into' anything, since as far as we know the Big Bang was the start of both space and time. Confusing, I know!
Astronomers aren't sure what caused the Big Bang. We just look at observations and see that's how the universe did start. We know it was extremely small and got bigger, and we know that kicked off 13.8 billion years ago.
What started our own game of chess? That's one of the deepest questions anyone can ask.
Hello, curious kids! Do you have a question you'd like an expert to answer? Ask an adult to send your question to CuriousKidsUS@theconversation.com. Please tell us your name, age and the city where you live.
And since curiosity has no age limit – adults, let us know what you're wondering, too. We won't be able to answer every question, but we will do our best.
This article is republished from The Conversation, a nonprofit, independent news organization bringing you facts and trustworthy analysis to help you make sense of our complex world. It was written by: Michael Lam, Rochester Institute of Technology
Read more:
After our universe's cosmic dawn, what happened to all its original hydrogen?
Hubble in pictures: astronomers' top picks
Curious Kids: Can people colonize Mars?
Michael Lam does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
Try Our AI Features
Explore what Daily8 AI can do for you:
Comments
No comments yet...
Related Articles
Yahoo
2 hours ago
- Yahoo
Why is AI halllucinating more frequently, and how can we stop it?
When you buy through links on our articles, Future and its syndication partners may earn a commission. The more advanced artificial intelligence (AI) gets, the more it "hallucinates" and provides incorrect and inaccurate information. Research conducted by OpenAI found that its latest and most powerful reasoning models, o3 and o4-mini, hallucinated 33% and 48% of the time, respectively, when tested by OpenAI's PersonQA benchmark. That's more than double the rate of the older o1 model. While o3 delivers more accurate information than its predecessor, it appears to come at the cost of more inaccurate hallucinations. This raises a concern over the accuracy and reliability of large language models (LLMs) such as AI chatbots, said Eleanor Watson, an Institute of Electrical and Electronics Engineers (IEEE) member and AI ethics engineer at Singularity University. "When a system outputs fabricated information — such as invented facts, citations or events — with the same fluency and coherence it uses for accurate content, it risks misleading users in subtle and consequential ways," Watson told Live Science. Related: Cutting-edge AI models from OpenAI and DeepSeek undergo 'complete collapse' when problems get too difficult, study reveals The issue of hallucination highlights the need to carefully assess and supervise the information AI systems produce when using LLMs and reasoning models, experts say. The crux of a reasoning model is that it can handle complex tasks by essentially breaking them down into individual components and coming up with solutions to tackle them. Rather than seeking to kick out answers based on statistical probability, reasoning models come up with strategies to solve a problem, much like how humans think. In order to develop creative, and potentially novel, solutions to problems, AI needs to hallucinate —otherwise it's limited by rigid data its LLM ingests. "It's important to note that hallucination is a feature, not a bug, of AI," Sohrob Kazerounian, an AI researcher at Vectra AI, told Live Science. "To paraphrase a colleague of mine, 'Everything an LLM outputs is a hallucination. It's just that some of those hallucinations are true.' If an AI only generated verbatim outputs that it had seen during training, all of AI would reduce to a massive search problem." "You would only be able to generate computer code that had been written before, find proteins and molecules whose properties had already been studied and described, and answer homework questions that had already previously been asked before. You would not, however, be able to ask the LLM to write the lyrics for a concept album focused on the AI singularity, blending the lyrical stylings of Snoop Dogg and Bob Dylan." In effect, LLMs and the AI systems they power need to hallucinate in order to create, rather than simply serve up existing information. It is similar, conceptually, to the way that humans dream or imagine scenarios when conjuring new ideas. However, AI hallucinations present a problem when it comes to delivering accurate and correct information, especially if users take the information at face value without any checks or oversight. "This is especially problematic in domains where decisions depend on factual precision, like medicine, law or finance," Watson said. "While more advanced models may reduce the frequency of obvious factual mistakes, the issue persists in more subtle forms. Over time, confabulation erodes the perception of AI systems as trustworthy instruments and can produce material harms when unverified content is acted upon." And this problem looks to be exacerbated as AI advances. "As model capabilities improve, errors often become less overt but more difficult to detect," Watson noted. "Fabricated content is increasingly embedded within plausible narratives and coherent reasoning chains. This introduces a particular risk: users may be unaware that errors are present and may treat outputs as definitive when they are not. The problem shifts from filtering out crude errors to identifying subtle distortions that may only reveal themselves under close scrutiny." Kazerounian backed this viewpoint up. "Despite the general belief that the problem of AI hallucination can and will get better over time, it appears that the most recent generation of advanced reasoning models may have actually begun to hallucinate more than their simpler counterparts — and there are no agreed-upon explanations for why this is," he said. The situation is further complicated because it can be very difficult to ascertain how LLMs come up with their answers; a parallel could be drawn here with how we still don't really know, comprehensively, how a human brain works. In a recent essay, Dario Amodei, the CEO of AI company Anthropic, highlighted a lack of understanding in how AIs come up with answers and information. "When a generative AI system does something, like summarize a financial document, we have no idea, at a specific or precise level, why it makes the choices it does — why it chooses certain words over others, or why it occasionally makes a mistake despite usually being accurate," he wrote. The problems caused by AI hallucinating inaccurate information are already very real, Kazerounian noted. "There is no universal, verifiable, way to get an LLM to correctly answer questions being asked about some corpus of data it has access to," he said. "The examples of non-existent hallucinated references, customer-facing chatbots making up company policy, and so on, are now all too common." Both Kazerounian and Watson told Live Science that, ultimately, AI hallucinations may be difficult to eliminate. But there could be ways to mitigate the issue. Watson suggested that "retrieval-augmented generation," which grounds a model's outputs in curated external knowledge sources, could help ensure that AI-produced information is anchored by verifiable data. "Another approach involves introducing structure into the model's reasoning. By prompting it to check its own outputs, compare different perspectives, or follow logical steps, scaffolded reasoning frameworks reduce the risk of unconstrained speculation and improve consistency," Watson, noting this could be aided by training to shape a model to prioritize accuracy, and reinforcement training from human or AI evaluators to encourage an LLM to deliver more disciplined, grounded responses. RELATED STORIES —AI benchmarking platform is helping top companies rig their model performances, study claims —AI can handle tasks twice as complex every few months. What does this exponential growth mean for how we use it? —What is the Turing test? How the rise of generative AI may have broken the famous imitation game "Finally, systems can be designed to recognise their own uncertainty. Rather than defaulting to confident answers, models can be taught to flag when they're unsure or to defer to human judgement when appropriate," Watson added. "While these strategies don't eliminate the risk of confabulation entirely, they offer a practical path forward to make AI outputs more reliable." Given that AI hallucination may be nearly impossible to eliminate, especially in advanced models, Kazerounian concluded that ultimately the information that LLMs produce will need to be treated with the "same skepticism we reserve for human counterparts."
Yahoo
2 hours ago
- Yahoo
A spinning universe could crack the mysteries of dark energy and our place in the multiverse
When you buy through links on our articles, Future and its syndication partners may earn a commission. What is dark energy? Why does dark energy seem to be weakening? Is our universe part of a larger multiverse? What lies beyond the boundary of a black hole?The universe seems to be rotating, and if that is the case, then this could have major ramifications for some of the biggest questions in science, including those above. That's according to Polish theoretical physicist Nikodem Poplawski of the University of New Haven, who is well-known for his theory that black holes act as doorways to other universes. "Dark energy is one of the most intriguing mysteries of the universe. Many researchers have tried to explain it by modifying equations of general relativity or suggesting the existence of new fields that could accelerate the universe's expansion," Poplawski told "It would be amazing if a simple rotation of the universe was the origin of dark energy, especially that it predicts its weakening." Evidence that the universe is rotating was recently delivered by the James Webb Space Telescope (JWST), which found that two-thirds of galaxies are rotating in the same direction. This suggests a lack of randomness and a preferred direction for cosmic rotation. Additionally, Poplawski pointed out that other astronomical data seem to show that the angle between the most likely axis of the spinning galaxies and the axis of the bulk flow of nearby galaxy clusters is 98 degrees, meaning they are nearly perpendicular in relation to each other. That is something that is in accordance with the hypothesis that the universe is rotating. To understand why a rotating universe implies more than one universe, Poplawski refers to "frames of reference." These are sets of coordinate systems that are integral to physics, which allow motion and rest to be measured. Imagine two scientists, Terra and Stella. Each is in their own frame of reference, but Terra on Earth, Stella in a spacecraft traveling past our planet. Terra sees Stella's frame of reference (the spacecraft) moving in relation to her own (the Earth), which is at rest. Stella, meanwhile, sees her frame of reference at rest while it is Terra's frame of reference in motion as the Earth races pointed out that if the universe is rotating, then its frame of reference is rotating, and that only makes sense if it is rotating in relation to at least one other frame of reference. "If the universe is rotating, it must rotate relative to some frame of reference corresponding to something bigger," he continued. "Therefore, the universe is not the only one; it is a part of a multiverse." For Poplawski, the simplest and most natural explanation of the origin of the rotation of the universe is black hole cosmology. Black hole cosmology suggests that every black hole creates a new baby universe on the other side of its event horizon, the one-way light-trapping surface that defines the outer boundary of a black hole. The theory replaces the central singularity at the heart of a black hole with "spacetime torsion" that gives rise to repulsive gravity that kick-starts the expansion of a new universe. "Because all black holes form from rotating objects, such as rotating stars or in the centers of rotating galaxies, they rotate too," Poplawski said. "The universe born in a rotating black hole inherits the axis of rotation of the black hole as its preferred axis." In other words, our universe may be spinning in a preferred direction because that is the way that the black hole it is sealed within is spinning. "A black hole becomes an Einstein-Rosen bridge or a 'wormhole' from the parent universe to the baby universe," Poplawski explained. "Observers in the new universe would see the other side of the parent black hole as a primordial white hole." In lieu of discovering a primordial white hole in our universe leading to our parent black hole and progenitor universe, the strongest evidence of this black hole cosmology is a preferred direction or "rotational asymmetry" in our universe. That can be seen in rotational asymmetry in the galaxies. "The motion of individual galaxies in that baby universe will be affected by the rotation of that universe," Poplawski said. "The galaxies will tend to align their axes of rotation with the preferred axis of the rotation of the universe, resulting in the rotation asymmetry, which can be observed."That's something astronomers are starting to course, that means that every black hole in our universe is a doorway to another baby cosmos. These infant universes are protected from investigation by the event horizon of their parent black holes, which prevents any signal from being received from the interior of a black a trip through this cosmic doorway would be impossible for a budding "multinaut" due to the immense gravity surrounding a black hole, which would give rise to tidal forces that would "spaghettify" such an intrepid explorer. Even if such a multinaut were to survive the journey, just as nothing can escape a black hole, nothing can enter a white hole, meaning there would be no return or opportunity to file a report! Even grimmer than this, there's no guarantee that the laws of physics are the same in a baby universe as their parent universe, meaning an unpredictable fate and potentially a messy death for a hardy multinaut able to brave a black hole doorway. Anyway, before we rush off to explore other universes, there are mysteries to be investigated right here in our own universe. At the forefront of these is the mysterious force of dark energy. Dark energy is a placeholder name given to whatever force is causing the universe to expand at an accelerating rate. Dark energy currently dominates the universe, accounting for 68% of the total cosmic matter-energy budget. This wasn't always the way, the universe's earliest epoch, it was dominated by the energy of the Big Bang, causing it to inflate. As the universe entered a matter-dominated epoch ruled by gravity, this inflation slowed to a near stop. This should have been it for the cosmos, but around 9 billion to 10 billion years after the Big Bang, the universe started to expand again, with this expansion accelerating, leading to the dark-energy dominated epoch. To understand why this is such a worrying puzzle, imagine giving a child on a swing a single push, watching their motion come to a halt, and then, for no discernible reason, they start swinging again, and this motion gets faster and faster. As if dark energy weren't strange enough already, recent results from the Dark Energy Spectroscopic Instrument (DESI) have indicated that this mysterious force is weakening. This is something that seemingly defies the standard model of cosmology or the Lambda Cold Dark Matter (LCDM) model, which relies on dark energy (represented by the cosmological constant or Lambda) being Poplawski theorizes that a spinning universe can both account for dark energy and explain why it is weakening. "Dark energy would emerge from the centrifugal force in the rotating universe on large scales," the theoretical physicist explained. "If the universe were flat, the centrifugal force would act only in directions perpendicular to the preferred axis." However, in Poplawski's black hole theory of cosmology, because the universe created by a black hole is closed, moving away in any direction would eventually lead to coming back from the opposite direction. That would mean the centrifugal force arising from a spinning universe becomes a force acting in all directions away from the universe's parent primordial white hole. "The magnitude of this force is proportional to the square of the angular velocity of the universe and the distance from the white hole," Poplawski said. "This relation takes the form of the force acting on a galaxy due to dark energy, which is proportional to the cosmological constant and the distance from the white hole. Therefore, the cosmological constant is proportional to the square of the angular velocity of the universe."But, how could this explain the DESI observations that seem to indicate that dark energy is getting weaker? "Because the angular momentum of the universe is conserved, it decreases as the universe expands," Poplawski said. "Consequently, the cosmological constant, which is the simplest explanation of dark energy, should also decrease with time. This result is consistent with recent observations by DESI." Related Stories: — Supermassive black holes in 'little red dot' galaxies are 1,000 times larger than they should be, and astronomers don't know why — 'Superhighways' connecting the cosmic web could unlock secrets about dark matter — How does the Cosmic Web connect Taylor Swift and the last line of your 'celestial address?'years To provide some further evidence of Poplawski's concept, more data on the bulk flow of galaxy clusters and on the asymmetry of galaxy rotation axes are needed. This would help further confirm that our universe is rotating. Additionally, more data regarding how dark energy depends on cosmic distances and the progression of time in our 13.7 billion-year-old cosmos could help validate whether the weakening of dark energy is related to the decreasing angular velocity of the universe. "The next step to advance these ideas is to determine the equation describing how the cosmological constant, generated by the angular velocity of the universe, decreases with time, and to compare this theoretical prediction with the observed decrease of dark energy," Poplawski concluded. "This research might involve searching for the metric describing an expanding and rotating universe."A pre-peer-reviewed version of Poplawski's research appears on the paper repository site arXiv.
Yahoo
2 hours ago
- Yahoo
Could trees know when the summer solstice is?
This article was originally featured on The Conversation. People have been celebrating the summer solstice with elaborate rituals since prehistoric times. But humans aren't the only species to take mark June 21 as a special time. Studies are showing the summer solstice is an important cue for plants too. Recent studies, including one of my own, have proposed that trees may use the longest day of the year as a key marker for their growth and reproductive cycles. The solstice seems to act like a calendar reminder for trees. For example, at the solstice, trees growing in cold places slow down the creation of new wood cells and focus their energy on finishing already formed but still incomplete cells. This ensures trees have time to complete cell construction before winter hits. Incomplete cells are damaged by freezing winter temperatures, rendering them useless for water transport the following year. Along similar lines, trees use the solstice to fine-tune the 'winding down', or senescence, of their leaves in preparation for autumn. Senescence allows the tree to reabsorb critical nutrients from the leaves before they fall. This process is timed to balance missing out on sunlight from 'winding down' too early, against leaving it too late and losing nutrients if still-green leaves are killed by autumn frosts. Satellite observations of forests, and controlled experiments in greenhouses, reveal that warmer temperatures immediately prior to the solstice cause the onset of leaf browning to start earlier that autumn. In contrast, warmer temperatures just after the solstice slow down the senescence process. This means a longer transition period from green to fully brown leaves. This fine-tuning enables trees to extend the period of photosynthesis in years when temperatures stay warmer for longer, so they don't miss out on these favourable conditions. But not all scientists are convinced. From an evolutionary perspective, the solstice may not be the best seasonal marker for timing these transitions. For example, in forests in the far north, leaves do not appear until early June, only days before the solstice, and the growing season can extend late into October. In these forests, using the solstice to initiate the winding down process makes little sense for trees that have only just started growing for the year. Nevertheless, there is more consensus about plants using the solstice to synchronise reproduction. In many plants, especially trees from the temperate mid-latitudes, the number of seeds they produce varies dramatically year on year, known as masting. A large European beech tree can produce hundreds of thousands of seeds in a bumper year (a 'mast event') and forgo reproduction altogether in other years. Beech trees vary their annual seed production in step, often on a continental scale. They do this to increase the efficiency of their reproduction. A small moth, Cydia fagiglandana, lays its eggs in beech flowers. When the grubs hatch, they eat and destroy the developing seeds. Cycles of famine and bumper years help protect their seeds from these moths. UK beech trees typically lose less than 5% of their seeds to Cydia because the cycles starve the moths into low numbers ready for masting years. But when trees are out of sync, seed loss can increase to over 40%. For decades we have known that beech mast events happen in the year after a warm summer. These warmer temperatures trigger an increase in the formation of flower buds. More flower buds usually lead to a greater crop of seeds that autumn. Scientists have long puzzled over how beech trees across Europe seem to use the same seasonal window to control mast events. Their seed production is determined by temperatures in late June and early July, irrespective of where they grow in Europe. But how can a beech tree know the date? In my team's 2024 study, we showed that they use the solstice as a seasonal marker. As soon as the days start to shorten after the solstice, beech trees across Europe seem to simultaneously sense the temperature. Anywhere temperatures are above average in the weeks following the solstice can expect to have a mast event the next year. Weather conditions in the weeks before the solstice, by contrast, seem to be irrelevant. As seen on weather maps, warm and cool spells tend to occur simultaneously over large areas. This allows beech trees to maximise the synchrony of their reproduction, whether that is investing in a mast year (warm temperatures), or forgoing reproduction for a year (low temperatures). Using a fixed marker like the solstice is the key to achieving this synchrony, and the benefits that come from it. The evidence for this phenomenon has come from observations across dozens of forests across Europe. However, my research group is collaborating with about a dozen other groups in Europe to test this effect by manipulating the temperature of beech branches before and after the solstice at different sites. Ongoing research I am involved with seems to show flowering genes are activated at the summer solstice. Also, studies into the circadian rhythms of plants show they have mechanisms in their molecules that allow them to detect and respond to tiny changes in day length. This is the basis for that extraordinary scale of synchronised reproduction. If the weather is warm over the next month or so, then there is a good chance that beech trees in your local area will have heavy seed crops next autumn. What's more, trees across the UK and into northern and central Europe will probably be doing the same.
