The universe is expanding, but what exactly is it expanding into? (continued)
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Colm Keenan Cramlington, Northumberland, UK
Perhaps the universe isn鈥檛 expanding. What if it is the yardstick we use to measure it that is contracting, and in some absolute sense the universe remains the same size, only seeming to expand because of the way we assume we can measure it?
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Andy Howe Sheffield, UK
Further to the previous correspondence (15 January), it is worth noting that if the universe is infinite, it must always have been infinite, including the impossibly dense seed of the big bang. The subsequent expansion merely renders it 鈥渕ore infinite鈥�, even accepting that it has nothing to expand into. (My head hurts鈥�)
A flat, infinite universe beyond our observable region is a popular option among cosmologists, as is indeed apparent from articles in 麻豆传媒, but this couldn鈥檛 have formed from a finite universe that had undergone inflation at an infinite speed.
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Patrick Verguet Besan莽on, France
Despite its apparent simplicity, I find myself confused by the classic analogy for an expanding universe as the surface of an inflating balloon. If I were a 2D ant walking within the boundary of an expanding sphere, why wouldn鈥檛 the distance between the elementary particles composing my body increase as well and my body itself inflate?
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Pauline Fothergill Pocklington, East Yorkshire, UK
May I add my mother鈥檚 perspective on this question? As an inquisitive preschooler, I remember asking her: 鈥淲hat is the sky actually in?鈥� She looked thoughtful, then eventually said: 鈥淥ur brains are not big enough for us to understand this.鈥�
I always hoped that, as I grew, I would find an answer 鈥� but clearly my dear old mum was right!
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