PeterDonis's latest activity
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PeterDonis replied to the thread Is mathematics invented or discovered?.I don't think your usage is consistent with others in this thread--they appear to me to be using "group" in the direct mathematical... -
PeterDonis replied to the thread Is mathematics invented or discovered?.Then at least some prime numbers are discovered--those that appear, for example, in the time periods of cicadas. -
PeterDonis replied to the thread Undergrad Milne vs. Minkowski metric.Yes, agreed. I think this depends on how you define what a "metric" is. Is it the geometry itself? Or is it the specific form of the... -
PeterDonis replied to the thread Is mathematics invented or discovered?.I agree; I think the distinction between "discovered" and "invented" that this thread is predicated on isn't clean either. -
PeterDonis replied to the thread Is mathematics invented or discovered?.I disagree. We conceptualize it in a particular way, but evolution does what it does whether humans conceptualize it or not, and what it... -
PeterDonis replied to the thread Is mathematics invented or discovered?.Primes aren't a group, mathematically speaking. They aren't closed under either addition or multiplication, the two operations present... -
PeterDonis replied to the thread Is mathematics invented or discovered?.What about the ways prime numbers show up in "natural" settings? For example, there are 13-year and 17-year cicadas. It is not a... -
PeterDonis reacted to PAllen's post in the thread Undergrad Comparing different scale factor functions in the same graph with
Like.
A better wording is simply that the time coordinate in Milne coordinates is different than the time coordinate in standard Minkowski... -
PeterDonis replied to the thread High School What is space?.@stephen h note that you marked this thread as "Graduate". If your answer to either of the questions I asked above is "no" (and I... -
PeterDonis replied to the thread High School What is space?.What page? Please give a specific link. What references? Be specific. Have you read any actual textbooks or peer-reviewed papers on... -
PeterDonis replied to the thread High School What is space?.We already have a detailed model of this in cosmology. Have you looked at it? -
PeterDonis replied to the thread Undergrad Comparing different scale factor functions in the same graph.More precisely, Milne is one "wedge" of MInkowski in different coordinates. So the Milne ##dt## is not the same as the Minkowski ##dt##... -
PeterDonis replied to the thread High School Can gravitons be detected?.@Josiah that's not a textbook or a peer-reviewed paper. You will have a very hard time finding one of those regarding Podkletnov's work... -
PeterDonis replied to the thread High School Can gravitons be detected?.If by "this experiment" you mean the claims by Podkletnov (which have never actually had any evidence for them), the answer is no.