<p>In special relativity, changes of reference frame are symmetric between observer and observee.  If moving a neutron star gave it enough kinetic energy to become a black hole, then you could effect this change by jumping into a moving reference frame yourself.</p>

<p>What matters is the neutron star's mass in its rest frame.</p>

CC BY-SA 4.0
2019-11-29T04:01:39.867Z
2019-11-29T04:01:39.867Z
rob
<p>Could a neutron star turn into a blackhole if it is accelerated to near luminal velocities? And if it slows down after a while, does it become a neutron star again?</p>

CC BY-SA 4.0
2019-11-24T12:38:56.747Z
No, if an object is a black hole in any inertial frame then it's a black hole in every inertial frame. Please see https://physics.stackexchange.com/q/3436/123208 and https://astronomy.stackexchange.com/q/32578/16685
PM 2Ring
CC BY-SA 4.0
2019-11-24T12:49:42.853Z
OTOH, if your speeding neutron star crashes into another body, then you will get a black hole if the total energy density (to be more precise, the [stress-energy-momentum](https://en.wikipedia.org/wiki/Stress%E2%80%93energy_tensor)) in the region is high enough, in other words, if the combined mass & kinetic energy is high enough.
PM 2Ring
CC BY-SA 4.0
2019-11-24T12:59:47.943Z
Also related: https://physics.stackexchange.com/q/512636/123208 BTW, some neutron stars are traveling quite fast relative to their galactic neighbours, eg https://en.wikipedia.org/wiki/IGR_J11014%E2%88%926103 but the speed is less than 1% of light speed.
PM 2Ring
CC BY-SA 4.0
2019-11-24T22:54:53.377Z
@PM2Ring ...what can happen in neutron star binaries if they finally collide.
peterh
CC BY-SA 4.0
2019-11-24T23:50:25.820Z
@peterh Depending on the mass & KE, you may get a larger neutron star, or a black hole. In either case, the collisions is likely to create (and eject) some heavy elements via the r-process, eg gold. See https://en.wikipedia.org/wiki/Neutron_star_merger and the periodic table at https://en.wikipedia.org/wiki/Nucleosynthesis#Timeline and https://arxiv.org/abs/1901.04138
PM 2Ring
<black-hole><neutron-star>
If we accelerate a neutron star to move at speeds comparable to light would it become a blackhole because of the added energy?
Manoj
# If we accelerate a neutron star to move at speeds comparable to light would it become a blackhole because of the added energy?

(Asked by: username_0 on 2019-11-24)

Could a neutron star turn into a blackhole if it is accelerated to near luminal velocities? And if it slows down after a while, does it become a neutron star again?

**Tags:** black-hole, neutron-star

> **Comments:**
> **username_1**: No, if an object is a black hole in any inertial frame then it's a black hole in every inertial frame. Please see https://physics.stackexchange.com/q/3436/123208 and https://astronomy.stackexchange.com/q/32578/16685  
> **username_1**: OTOH, if your speeding neutron star crashes into another body, then you will get a black hole if the total energy density (to be more precise, the [stress-energy-momentum](https://en.wikipedia.org/wiki/Stress%E2%80%93energy_tensor)) in the region is high enough, in other words, if the combined mass & kinetic energy is high enough.  
> **username_1**: Also related: https://physics.stackexchange.com/q/512636/123208 BTW, some neutron stars are traveling quite fast relative to their galactic neighbours, eg https://en.wikipedia.org/wiki/IGR_J11014%E2%88%926103 but the speed is less than 1% of light speed.  
> **username_2**: @PM2Ring ...what can happen in neutron star binaries if they finally collide.  
> **username_1**: @username_2 Depending on the mass & KE, you may get a larger neutron star, or a black hole. In either case, the collisions is likely to create (and eject) some heavy elements via the r-process, eg gold. See https://en.wikipedia.org/wiki/Neutron_star_merger and the periodic table at https://en.wikipedia.org/wiki/Nucleosynthesis#Timeline and https://arxiv.org/abs/1901.04138  

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## 1 answers

### Answer by username_3 on 2019-11-29. Score: 1

In special relativity, changes of reference frame are symmetric between observer and observee. If moving a neutron star gave it enough kinetic energy to become a black hole, then you could effect this change by jumping into a moving reference frame yourself.

What matters is the neutron star's mass in its rest frame.


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