display all the ideas for this combination of texts
22 ideas
19950 | Entropy is the only time-asymmetric law, so time may be linked to entropy [New Sci.] |
Full Idea: All our physical laws are time-symmetric, ...so things can run forwards or backwards. But entropy is an exception, saying that disorder increases over time. Many physicists therefore suspect that the flow of time is linked to entropy. | |
From: New Scientist writers (New Scientist articles [2013], 2017.02.04) |
19478 | Light moves at a constant space-time speed, but its direction is in neither space nor time [New Sci.] |
Full Idea: A light ray always moves at one unit of space per unit of time - a constant diagonal on the graph. ...But the direction that light rays travel in is neither space nor time, and is called 'null'. It is on the edge between space and time. | |
From: New Scientist writers (New Scientist articles [2013], 2013.06.15) | |
A reaction: Don't understand this, but it sounds fun. |
19474 | Quantum states are measured by external time, of unknown origin [New Sci.] |
Full Idea: When we measure the evolution of a quantum state, it is to the beat of an external timepiece of unknown provenance. | |
From: New Scientist writers (New Scientist articles [2013], 2013.06.15) | |
A reaction: It is best not to leap to philosophical conclusions when studying modern physics. Evidently time has a very different status in quantum mechanics and in relativity theory. |
19473 | The Schrödinger equation describes the evolution of an object's wave function in Hilbert space [New Sci.] |
Full Idea: A quantum object's state is described by a wave function living in Hilbert space, encompassing all of its possible states. We see how the wave function evolves in time, moving from one state to another, using the Schrödinger equation. | |
From: New Scientist writers (New Scientist articles [2013], 2013.06.15) | |
A reaction: [These idea are basic explanations for non-scientific philosophers - please forgive anything that makes you wince] |
19953 | In string theory space-time has a grainy indivisible substructure [New Sci.] |
Full Idea: String theory suggests that space-time has a grainy substructure - you can't keep chopping it indefinitely into smaller and smaller pieces. | |
From: New Scientist writers (New Scientist articles [2013], 2015.11.07) | |
A reaction: Presumably the proposal is that strings are the true 'atoms'. |
19954 | It is impossible for find a model of actuality among the innumerable models in string theory [New Sci.] |
Full Idea: String theory has more than 10-to-the-500th solutions, each describing a different sort of universe, so it is nigh-on impossible to find the one solution that corresponds to our geometrically flat, expanding space-time full of particles. | |
From: New Scientist writers (New Scientist articles [2013], 2015.11.07) |
19476 | String theory needs at least 10 space-time dimensions [New Sci.] |
Full Idea: String theory needs at least 10 space-time dimensions to be mathematically consistent. | |
From: New Scientist writers (New Scientist articles [2013], 2013.06.15) | |
A reaction: Apparently because of 'Ads/CFT', it may be possible to swap this situation for a more tractable 4-dimensional version. |
19947 | Hilbert Space is an abstraction representing all possible states of a quantum system [New Sci.] |
Full Idea: The elements of the abstract mathematical entity called Hilbert Space represent all the possible states of a quantum system | |
From: New Scientist writers (New Scientist articles [2013], 1017.02.04) |
19955 | Space-time may be a geometrical manifestation of quantum entanglement [New Sci.] |
Full Idea: A promising theory (based on the 'Maldacena duality' - that string equations for gravity are the same as quantum equations for surface area) is that space-time is really just geometrical manifestations of quantum entanglement. | |
From: New Scientist writers (New Scientist articles [2013], 2015.11.07) | |
A reaction: This is a speculation which might unite the incompatible quantum and general relativity theories. |
19948 | Einstein's merging of time with space has left us confused about the nature of time [New Sci.] |
Full Idea: Our hunt for the most basic ingredients of reality has left us muddled about the status of time. One culprit for this was Einstein, whose theory of general relativity merged time with space. | |
From: New Scientist writers (New Scientist articles [2013], 2017.02.04) |
19475 | Relativity makes time and space jointly basic; quantum theory splits them, and prioritises time [New Sci.] |
Full Idea: Relativity says space and time are on the same footing - together they are the fabric of reality. Quantum mechanics, on the other hand, treats time and space differently, with time occasionally seeming more fundamental. | |
From: New Scientist writers (New Scientist articles [2013], 2013.06.15) | |
A reaction: Interesting. When talking about time, people glibly cite relativistic space-time to tell you that time is just another dimension. Now I can reply 'Aaah, but what about time in quantum mechanics? Eh? Eh?'. Excellent. |
19949 | Quantum theory relies on a clock outside the system - but where is it located? [New Sci.] |
Full Idea: After general relativity, quantum mechanics reinstated our familiar notion of time. The buzzing of the quantum world plays out according to the authoritative tick of a clock outside the described system, ...but where is this clock doing its ticking? | |
From: New Scientist writers (New Scientist articles [2013], 2017.02.04) |
9666 | It is quite implausible that the future is unreal, as that would terminate everything [Lewis] |
Full Idea: It is hard to believe that any philosopher means it when they say the future is unreal. If anyone is right that there is no future, that moment is their last, and it is the end of everything. | |
From: David Lewis (On the Plurality of Worlds [1986], 4.2) | |
A reaction: A bit simplistic. I might say 'there will be a future time, but it doesn't exist now'. That's the peculiar thing about time. If I say New York doesn't exist, then clearly I can't visit it. The London 2012 Olympic Stadium is going to exist. |
20819 | The past and the future subsist, but only the present exists [Chrysippus, by Plutarch] |
Full Idea: When he wished to be subtle, Chrysippus wrote that the past part of time and the future part do not exist but subsist, and only the present exists. | |
From: report of Chrysippus (fragments/reports [c.240 BCE]) by Plutarch - On Common Conceptions 1081f | |
A reaction: [from lost On Void] I think I prefer the ontology of Idea 20818. Idea 20819 does not offer an epistemology. Is the present substantial enough to be known? The word 'subsist' is an ontological evasion (even though Russell briefly relied on it). |
19951 | Entropy is puzzling, so we may need to build new laws which include time directionality [New Sci.] |
Full Idea: Smolin observes that if entropy increases, the early universe must have been highly ordered, which we cannot explain. Maybe we need to build time directionality into the laws, instead of making time depend on entropy. | |
From: New Scientist writers (New Scientist articles [2013], 2017.02.04) | |
A reaction: [compressed] |
20818 | The present does not exist, so our immediate experience is actually part past and part future [Chrysippus, by Plutarch] |
Full Idea: Stoics do not allow a minimal time to exist, and do not want to have a partless 'now'; so what one thinks one has grasped as present is in part future and in part past. | |
From: report of Chrysippus (fragments/reports [c.240 BCE]) by Plutarch - On Common Conceptions 1081c | |
A reaction: [from lost On Parts Bk3-5] I agree with the ontology here, but I take our grasp of the present to be very short-term memory of the past. I ignore special relativity. Chrysippus expressed two views about this; in the other one he was a Presentist. |
20821 | Time is continous and infinitely divisible, so there cannot be a wholly present time [Chrysippus, by Stobaeus] |
Full Idea: Chrysippus says most clearly that no time is wholly present; for since the divisibility of continuous things is infinite, time as a whole is also subject to infinite divisibility by this method of division. | |
From: report of Chrysippus (fragments/reports [c.240 BCE]) by John Stobaeus - Anthology 1.08.42 | |
A reaction: But what is his reason for thinking that time is a continuous thing? There is a minimum time in quantum mechanics (the Planck Time), but do these quantum intervals overlap? Compare Idea 20819. |
19952 | Black holes have entropy, but general relativity says they are unstructured, and lack entropy [New Sci.] |
Full Idea: Black holes have a temperature, and hence entropy. ...But if a black hole are just an extreme scrunching of smooth space-time, it should have no substructure, and thus no entropy. This is probably the most obvious incompleteness of general relativity. | |
From: New Scientist writers (New Scientist articles [2013], 2015.11.07) |
19477 | General relativity predicts black holes, as former massive stars, and as galaxy centres [New Sci.] |
Full Idea: Black holes are predicted by general relativity, and are thought to exist where massive stars once lived, as well as at the heart of every galaxy. | |
From: New Scientist writers (New Scientist articles [2013], 2013.06.15) | |
A reaction: Since black holes now seem to be a certainty, that is one hell of an impressive prediction. |
16420 | 84.5 percent of the universe is made of dark matter [New Sci.] |
Full Idea: Dark matter makes up 84.5 percent of the universe's matter. | |
From: New Scientist writers (New Scientist articles [2013], 2013.10.29) |
17604 | We are halfway to synthesising any molecule we want [New Sci.] |
Full Idea: Ei-ichi Negishi (Nobel chemist of 2010) says 'the ultimate goal is to be able to synthesise any molecule we want. We are probably about halfway there'. | |
From: New Scientist writers (New Scientist articles [2013], 2010.10.16) |
17603 | Chemistry just needs the periodic table, and protons, electrons and neutrinos [New Sci.] |
Full Idea: Ei-ichi Negishi (Nobel chemist of 2010) says 'I work with the periodic table in front of me at all times, and approach all challenges in terms of three particles, positively charged protons, negatively charged electrons, and neutral neutrinos'. | |
From: New Scientist writers (New Scientist articles [2013], 2010.10.16) |