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Curious Kids<\/a> is a series for children of all ages. If you have a question you\u2019d like an expert to answer, send it to CuriousKidsUS@theconversation.com<\/a>.<\/p>\n Are multiverses real? If so, what do they look like? How do you get there without disturbing time? \u2013 Emily, age 9, Pune, Maharashtra, India<\/p>\n The idea of a multiverse<\/a> \u2013 a hypothetical collection of all possible universes \u2013 is one that To answer the question of whether the multiverse is real, we first need to agree on what it means for something to be real. As an astrophysicist who studies cosmology<\/a> \u2013 the large-scale history and structure of the universe \u2013 and the philosophy of physics, I\u2019ve thought about this question more than a few times over my career.<\/p>\n The most immediate definition of \u201creal\u201d might be that you can see and touch it<\/a>. My lunch is real in this sense, because I can taste it and you can hear me chewing it (hopefully not too loudly). So \u201creal\u201d might be defined as something you can perceive with at least one of your five senses. <\/p>\n But that would leave out a lot of things that are also real. The microwaves that heat up your food are real, but you can\u2019t directly perceive them \u2013 only their effect, heated food. So some real things you can \u201csee\u201d only indirectly by the evidence they leave behind. The existence of dinosaurs<\/a> is another example \u2013 you can see only their fossils.<\/p>\n So, you can ask two versions of the question of whether the multiverse is real. One: Can you see, hear, touch, smell or taste it? Two: Even if you can\u2019t, is there any evidence of its effects?<\/p>\n Quantum mechanics of the multiverse<\/p>\n The answer most researchers would offer to whether you can perceive the multiverse with your five senses is probably not. But there are lots of real things that aren\u2019t real in this sense, such as microwaves. So can we see any indirect evidence of the multiverse, such as the effects it might have on the observable world? <\/p>\n The short answer is yes, sort of. <\/p>\n The multiverse is one way to understand the behavior of very, very small things, such as atoms and subatomic particles. Scientists call the rules governing how these very small objects behave quantum mechanics<\/a>. In quantum mechanics, it\u2019s never certain what the outcome of an experiment will be. You can only write down the chance \u2013 that is, the probability \u2013 of something happening. <\/p>\n<\/p>\n Schr\u00f6dinger\u2019s cat illustrates how multiple possibilities can exist at the same time.<\/p>\n It\u2019s like rolling dice: You can\u2019t be sure what number you\u2019ll get, but you can say you have an equal chance of getting one, two, three, four, five or six on top of the dice. However, if you knew enough information about the dice \u2013 such as its exact shape and mass, the air patterns around it and the exact way you threw it \u2013 you could predict exactly what side it would land on. It might take a big computer simulation to crunch the numbers, but it\u2019s possible.<\/p>\n Now imagine really, really, really small dice. Even if you had a very powerful computer, you wouldn\u2019t be able to predict which side this super small dice would fall on. That\u2019s because it\u2019s governed by quantum mechanics, where you can\u2019t predict outcomes with complete certainty. You can predict only probability.<\/p>\n Many worlds and the multiverse<\/p>\n Quantum mechanics is only somewhat random<\/a> \u2013 not everything has an equal chance of happening. We can predict the chance of each scenario happening, but not the actual outcome. In the case of quantum dice, all we could know about it is that there\u2019s a 1 in 6 chance of it landing on any face.<\/p>\n One way scientists have interpreted this strange property of quantum mechanics is that each possible scenario actually does happen. But when it does, it creates another universe. This is called the many-worlds view of quantum mechanics<\/a>.<\/p>\n In the case of our quantum dice, the many-worlds view would say there\u2019s a 1 in 6 chance of rolling each number because six universes are created every time we roll the dice. Although we stay in one of them \u2013 say, the world where the dice comes up three \u2013 five other universes are also created where the dice comes up as one of the other numbers. <\/p>\n In this picture of quantum mechanics, universes branch off with every scenario. Of course, we cannot really make a quantum mechanical dice and roll it \u2013 just interacting with the dice would destroy its quantum nature. <\/p>\n Does this mean quantum mechanics is evidence that the multiverse is real? I would say no. While it\u2019s a fascinating way to imagine quantum mechanics, it\u2019s just one interpretation, not undeniable evidence of the multiverse.<\/p>\n If multiple universes possibly exist but you aren\u2019t able to perceive any of them, do they actually exist? The multiverse and string theory<\/p>\n Another relevant aspect of the multiverse is its role in string theory<\/a>. String theory argues that the fundamental particles that make up matter are themselves made of vibrating strings of energy. Think of an elastic band vibrating inside each particle.<\/p>\n String theory also argues that the universe has more than three dimensions. Different string theories predict different numbers of extra dimensions. This means physical constants such as the speed of light and the charge of electrons could have different values. So could the amount of stuff in the universe, such as matter. That suggests a landscape of possible different universes<\/a>, each with different conditions \u2013 a multiverse.<\/p>\n So far, there isn\u2019t definite evidence of a multiverse based on string theory. These universes probably wouldn\u2019t connect to each other, otherwise they wouldn\u2019t count as separate universes \u2013 just part of our own. So even if they do exist, we may never get direct evidence for their existence.<\/p>\n However, there could be indirect evidence of the existence of multiple universes. For instance, string theory can help scientists predict the results of very high-energy experiments in our own universe. It can also make predictions for how matter behaves on very, very small scales. If these predictions turn out to be true, that could be evidence for string theory. And if string theory is possibly real in our universe, this indirectly means the multiverse may also be real.<\/p>\n
\nscience fiction fans love to explore. But does the multiverse actually exist? <\/p>\n![\"Illustration](\"https:\/\/www.newsbeep.com\/ca\/wp-content\/uploads\/2026\/03\/file-20260320-68-4vta1l.jpg\")
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\n Victor de Schwanberg\/Science Photo Library via Getty Images<\/a><\/p>\n