[Azhar (OP)]

Hello all,

Newbie here with no background in science whatsoever.

I've a question regarding dark matter. I understand that we know dark matter exists because it causes to affect how galaxies are shaped outerly. But yet we are not able to detect it using various means.

My question is, if it doesn't interact with anything we know so far and hence we have not been able to detect then how is it interacting to form the shape of the galaxies? After all IT IS interacting with the mass/gravity within galaxy to have an affect in their shape.

Thanks in advance.

[jeffreyH]

For the effects observed to happen within galaxies to be explained, the dark matter must be a source of a gravitational field. In this way it can interact with ordinary matter without being affected by electromagnetic interactions. It is the lack of the  more energetic interactions that preclude detection of this matter with current technology. The data from galaxy rotation profiles indicate that there is in fact missing mass. Where observation shows a particular phenomena to happen then it is the job of theories to explain observations and hopefully make new predictions that can then be tested. It was theory alone that predicted the existence of gravitational waves. So in some cases extrapolation of existing theories alone can be enough. If there is enough supporting data that indicates a general direction to explore. The universe will always surprise us since we do not have all the pertinent observational evidence required to know everything. Nor are we likely to ever have it. That is why science is an open field.

[syhprum]

Dark matter apparently interacts only via gravity, gravity is an incredibly weak force compared to the atomic forces via which we see the world and only now are we begining to build machines that can detect the gravitational energy given of by colliding black holes a neutron stars.