I taught a lecture on radiation source in my introduction to nondestructive evaluation (NDE) course in late March 2022. During the lecture I thought to myself, “What if you could use a black hole as your x-ray source?” I know that this idea is far from being possible with today’s current technology and may be a bit controversial. But, I wonder how the NDE industry (particularly radiography) would change if using black holes was feasible.

First, it is important to explain why the NDE industry would use x-rays. The welding industry uses radiation/x-rays to inspect welds without the need of destroying them to test their structural and mechanical integrity for their designed applications. Radiographic testing (RT) is similar to when a person goes into a hospital and gets an x-ray on a part of their body to check for damage to internal organs or bones. X-rays can be produced in a vacuum tube by applying electrical current heat up a coil filament (normally tungsten) to produce electrons [1]. These electrons are then focused at high speed to collide into a tungsten anode target and produce x-rays. These x-rays are then focused onto the component to be inspected by focusing the x-ray beam with an electrostatic focusing cup.

What if we could use x-rays generated from a black hole to inspect welds? Another question would also arise on whether x-rays generated from black holes are different from the x-rays that we use in RT? Based on these questions, let take a trip together to figure out the answers to them.

Side note: This was a thought experiment on whether you can use Hawking radiation for NDE, but I researched and found that Hawking radiation is the process of a black hole evaporating by collection of hypothesized particles emitted on the edge of black hole’s event horizon [2, 3]. I found the idea of Hawking radiation fascinating but using this form of radiation as a penetrating medium for NDE would not be possible.

Based on my research on black holes, they can emit x-rays from hot gases that orbit around them [4]. If this is the case, then we could presume that a black hole could be used as an x-ray source similar to the anode target in an x-ray tube. In the case of a black hole one would have to “feed” it matter or create a gas cloud around it to produce the x-rays. Both pose a slippery slope that could cause the black hole to grow in size. Black hole are mysterious cosmic bodies that may not be controllable if used for NDE. If one were to harness the power of a black hole to simply perform weld inspection extreme safety measures would have to be taken to ensure that nothing goes past the black hole’s event horizon. RT is already an safety-intensive process and adding one of the most powerful bodies in the known universe to just get x-rays may be overkill. But it is fun to imagine by combining two disciplines together and wonder the outcome.

Thank you for your time!

–DB PhD

References

  1. Prabhu, S., Naveen, D. K., Bangera, S., & Bhat, B. S. (2020, December). Production of X-Rays Using X-Ray Tube. In Journal of Physics: Conference Series (Vol. 1712, No. 1, p. 012036). IOP Publishing.
  2. Jiang, Q. Q., Wu, S. Q., & Cai, X. (2006). Hawking radiation as tunneling from the Kerr and Kerr-Newman black holes. Physical Review D, 73(6), 064003.
  3. Kurzgesagt – In a Nutshell. (2016). Black Holes Explained – From Birth to Death [Video]. Youtube. https://www.youtube.com/watch?v=e-P5IFTqB98.
  4. Cox, T. J., Di Matteo, T., Hernquist, L., Hopkins, P. F., Robertson, B., & Springel, V. (2006). X-ray emission from hot gas in galaxy mergers. The Astrophysical Journal, 643(2), 692.