Recent content by Lanniakea

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    I Thought experiment: Communication beyond the particle horizon

    Refer to this image: http://imgur.com/xT20HOv The white nodes are 'stations' which broadcast signals at light speed. The blue circles around them represent the particle horizon relative to these nodes. The pink nodes are intermediary stations in between these stations that pass on the signal...
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    Finding distance for a given value between vectors

    Ah I haven't done any maths in so long I had even forgotten basic factorization, I also thought that (k+1)2 = k2 + 12 for some reason, what a sin of a mistake! Thank you very much my friend.
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    Finding distance for a given value between vectors

    I redid the working (both d(u,v) and d(v,u) which turn out to be the same so it seems correct this time) and get k = √8 I really have no idea what I'm doing wrong, can you specify where my mistake is? I have a lot more work to catch up on and I'm struggling with the basics... and by ||u−v||...
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    Finding distance for a given value between vectors

    Homework Statement Let u = (2,k,1,-4) and v = (3,-1,6,-3) For which values of k is the distance d(u,v) = 6? Homework EquationsThe Attempt at a Solution 6 = √((3-2)2 + (-1-k)2 + (6-1)2 + (-3-4)2) 6 = √(1 + 1 + k2 + 25 + 21) 6 = √(k2 + 48) 36 = k2 + 48 k = √-12 The answers seem to be 6k, -16k...
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    A KIC 8462852 (dipping again in March 2018)

    So it is reasonable to believe that the nearby passing star could've directed a comet from it's own system or the oort cloud (origin doesn't matter too much I suppose) towards Tabby's star, which is when it created a coma as it got close, then this coma was shifted around by...
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    A KIC 8462852 (dipping again in March 2018)

    We missed a transit in April, when Kepler was nonfunctional. The next one is predicted to be roughly in May 2017. What's odd about the curves is that the first transit is so smooth and well defined, while the second one is so chaotically distributed. The two small dips at the beginning of the...
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    A KIC 8462852 (dipping again in March 2018)

    Thank you so much for this, when you explain it like that it becomes almost obvious! :eek: They talk about about a nearby star within about 1000AU passing by that could of in theory disturbed the star's oort cloud in a way that sent a massive cloud of fragments that somehow ended up in an orbit...
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    A KIC 8462852 (dipping again in March 2018)

    The object has a period of about 750 days and the first time it passed it created a 15% dip, and then 750 days later a 22% dip + many smaller dips around this time. I'm by no means an astronomer, but what kind of diffuse object or even pack of comets blocks 61-74% of the sun's radius worth of...
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    A KIC 8462852 (dipping again in March 2018)

    Thank you! My only question is, how much would the distance from the star contribute? For example let's say Jupiter was orbiting this star at 2 AU away, would it not theoretically block more light from our perspective if it were say 8 AU away? It is established that this object does orbit the...
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    Metric expansion misunderstanding

    This is absolutely blowing my mind right now. I have at least 6 million questions. I always thought of gravitational effects and metric expansion as something exclusive, or at least not directly related. What determines if energy will contribute towards 'expanding' or 'deforming' space? At...
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    Metric expansion misunderstanding

    Hmm! I think of gravitational effects as deformations of space-time. So all objects follow geodesics in this deformed space-time, whereas the expansion of space I perceive as the literal expansion of space-time, or the coordinate system that defines it. Am i correct in thinking this? Is there...
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    Metric expansion misunderstanding

    So my understanding is correct - the wiki article is misleading then! How dare you call me fat! Since we're roughly in this topic, allow me another semi-related question. The fundamental source for gravity is ultimately energy correct? When we say 'mass' we mean the magnitude of four-momentum...
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    Metric expansion misunderstanding

    Here is the second paragraph from the article on metric expansion of space from Wikipedia Metric expansion is a key feature of Big Bang cosmology, is modeled mathematically with the FLRW metric, and is a generic property of the Universe we inhabit. However, the model is valid only on large...
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    A KIC 8462852 (dipping again in March 2018)

    Can someone point me towards the mathematics behind estimating the size of an object from the dip in light curve? I read somewhere (I can't remember for the life of me where) that if the object blocking this star was the size of Jupiter, the dip in flux would have been less than 1%. This is a...
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