8 ms·

Does this mean that black holes possibly might not even exist? Aren't there examples of them being directly observed?

by nautilus12 8y ago

sulam 8y ago
We have observed their x-ray jets directly and have observed their creation (recently). Pretty sure they exist. :)
- oldandtired 8y ago
  Let's change this a little bit. We have observed specific phenomena but not that which created such phenomena. As far as "Black Holes" as per theoretical descriptions are concerned, they cannot exist in a finite time universe as far as we (the observers) are concerned. The theoretical models used all have as a basic assumption that increasing gravity (whatever that may be) will cause a slow down in time as observed at distances away from such increase. As such, all phenomena involved in the creation of such entities will slow to a complete stop as far as we are concerned. Hence, if the universe is of any finite duration, we will not have seen the creation of even 1 black hole of any kind. On the other hand, if the universe has existed eternally, it is still likely that these entities are still in the process of formation and not yet in existence. I don't doubt we are seeing some interesting phenomena, but not the entities called "Black Holes". The argument for the creation involves changing perspective to some observer who is falling into or through the event horizon (choose which one of these you want, as there are apparently a couple of choices here in the theoretical models). Since we are not such observers, that perspective is actually irrelevant to us. What is relevant is what we observe in the universe at large. The basic problems (irrespective of mathematical assumptions) with the processes of "Black Hole" generation relate to non-uniformity of compression, time dilation and other basic assumptions for the "Black Hole" models. I find the reasoning used for the existence of "Black Holes" in our universe to be lacking in logical rigour and appears to have a lot of hand-waviness to it. I am currently reading the documentation for the Metamath system and there are some quite enlightening comments in that about mathematics and those who study it. Especially as it relates to us who are not mathematicians as our career. One of these relates to the amount of "faith" we have to exhibit when trusting that specific "proofs" are in point of fact true. Even mathematicians who are not in that specific speciality do not have the necessary background to verify any proof outside of their own mathematical area. Mathematics is a profoundly useful tool but as we have seen in the past and we will see in the future, it has problems (like all areas).
  - InclinedPlane 8y ago
    We have observed matter falling into a black hole. We've watched "hot spots" in orbit of a black hole in the accretion disk shine their light at us as they orbited the black hole. We've watched as the orbit got tighter and tighter and the light was dimmed by gravitational red shifting, then we've watched the light blink out and disappear as the blob of gas fell below the event horizon. The evidence for the existence of black holes is incredibly strong at the moment. In fact in some ways it's stronger than the evidence for the existence of atoms about a century ago. Nobody except cranks or extreme contrarians seriously disputes the theory these days.
    - roywiggins 8y ago
      I believe the argument is that event horizons exist but inside is not a singularity, but an eternally collapsing mass of the original star. From the point of view of the star, it does collapse all the way, but from our point of view that final singularity collapse is in the indefinite future. https://en.m.wikipedia.org/wiki/Magnetospheric_eternally_collapsing_object https://en.m.wikipedia.org/wiki/Magnetospheric_eternally_col...
      - roywiggins 8y ago
        Update: I am mistaken. The classic GR black hole behaves this way. MECOs supposedly never fully collapse into a singularity, even for infalling observers. That's the difference. I rather think we'd have noticed the difference from LIGO gravitational wave measurements of BH mergers, but maybe not?
    - perl4ever 8y ago
      From your point of view, if so-called black holes are "fuzzballs"[1] is that a vindication or a refutation of the existence of black holes? Without a deep understanding of physics, I have the general attitude that infinities must be a mathematical error, and therefore something must stop black holes from collapsing totally, but whether they "exist" is only a matter of definitions. [1]https://en.wikipedia.org/wiki/Fuzzball_(string_theory) https://en.wikipedia.org/wiki/Fuzzball_(string_theory)
TrainedMonkey 8y ago
No black holes absolutely exist. The researches have established an upper limit on the fraction of mass of black holes compared to all of the matter in universe. Per quote below this comes out to no more than than 23%. " An as-yet unpublished reanalysis by the same team using an updated list of 1,048 supernovas cuts the limit in half, to a maximum of about 23 percent, further slamming the door on the dark matter-black hole proposal. " Since dark matter makes up 85% of total matter this rules out black holes as the primary contributor.

Does this mean that black holes possibly might not even exist? Aren't there examples of them being directly observed?

sulam 8y ago

We have observed their x-ray jets directly and have observed their creation (recently). Pretty sure they exist. :)

oldandtired 8y ago
Let's change this a little bit. We have observed specific phenomena but not that which created such phenomena. As far as "Black Holes" as per theoretical descriptions are concerned, they cannot exist in a finite time universe as far as we (the observers) are concerned. The theoretical models used all have as a basic assumption that increasing gravity (whatever that may be) will cause a slow down in time as observed at distances away from such increase. As such, all phenomena involved in the creation of such entities will slow to a complete stop as far as we are concerned. Hence, if the universe is of any finite duration, we will not have seen the creation of even 1 black hole of any kind. On the other hand, if the universe has existed eternally, it is still likely that these entities are still in the process of formation and not yet in existence. I don't doubt we are seeing some interesting phenomena, but not the entities called "Black Holes". The argument for the creation involves changing perspective to some observer who is falling into or through the event horizon (choose which one of these you want, as there are apparently a couple of choices here in the theoretical models). Since we are not such observers, that perspective is actually irrelevant to us. What is relevant is what we observe in the universe at large. The basic problems (irrespective of mathematical assumptions) with the processes of "Black Hole" generation relate to non-uniformity of compression, time dilation and other basic assumptions for the "Black Hole" models. I find the reasoning used for the existence of "Black Holes" in our universe to be lacking in logical rigour and appears to have a lot of hand-waviness to it. I am currently reading the documentation for the Metamath system and there are some quite enlightening comments in that about mathematics and those who study it. Especially as it relates to us who are not mathematicians as our career. One of these relates to the amount of "faith" we have to exhibit when trusting that specific "proofs" are in point of fact true. Even mathematicians who are not in that specific speciality do not have the necessary background to verify any proof outside of their own mathematical area. Mathematics is a profoundly useful tool but as we have seen in the past and we will see in the future, it has problems (like all areas).
- InclinedPlane 8y ago
  We have observed matter falling into a black hole. We've watched "hot spots" in orbit of a black hole in the accretion disk shine their light at us as they orbited the black hole. We've watched as the orbit got tighter and tighter and the light was dimmed by gravitational red shifting, then we've watched the light blink out and disappear as the blob of gas fell below the event horizon. The evidence for the existence of black holes is incredibly strong at the moment. In fact in some ways it's stronger than the evidence for the existence of atoms about a century ago. Nobody except cranks or extreme contrarians seriously disputes the theory these days.
  - roywiggins 8y ago
    I believe the argument is that event horizons exist but inside is not a singularity, but an eternally collapsing mass of the original star. From the point of view of the star, it does collapse all the way, but from our point of view that final singularity collapse is in the indefinite future. https://en.m.wikipedia.org/wiki/Magnetospheric_eternally_collapsing_object https://en.m.wikipedia.org/wiki/Magnetospheric_eternally_col...
    - roywiggins 8y ago
      Update: I am mistaken. The classic GR black hole behaves this way. MECOs supposedly never fully collapse into a singularity, even for infalling observers. That's the difference. I rather think we'd have noticed the difference from LIGO gravitational wave measurements of BH mergers, but maybe not?
  - perl4ever 8y ago
    From your point of view, if so-called black holes are "fuzzballs"[1] is that a vindication or a refutation of the existence of black holes? Without a deep understanding of physics, I have the general attitude that infinities must be a mathematical error, and therefore something must stop black holes from collapsing totally, but whether they "exist" is only a matter of definitions. [1]https://en.wikipedia.org/wiki/Fuzzball_(string_theory) https://en.wikipedia.org/wiki/Fuzzball_(string_theory)

TrainedMonkey 8y ago

No black holes absolutely exist. The researches have established an upper limit on the fraction of mass of black holes compared to all of the matter in universe. Per quote below this comes out to no more than than 23%. " An as-yet unpublished reanalysis by the same team using an updated list of 1,048 supernovas cuts the limit in half, to a maximum of about 23 percent, further slamming the door on the dark matter-black hole proposal. " Since dark matter makes up 85% of total matter this rules out black holes as the primary contributor.